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Pathogenesis CO2 Pneumoperitoneum-Induced Metabolic Hypoxemia in a Rabbit Model
Abstract
To investigate the effects of carbon dioxide (CO(2)) pneumoperitoneum-induced changes in blood gases, acid-base balance, and oxygen homeostasis in rabbits.
Prospective, randomized, controlled study (Canadian Task Force classification I).
University training and teaching center.
Twenty-six adult female New Zealand white rabbits.
Anesthesia and pneumoperitoneum.
In anesthetized rabbits arterial blood gases, acid-base balance, oxygenation values, and lactate concentrations were assayed during 2 hours. Spontaneous breathing, superficial and optimal ventilation without pneumoperitoneum, and with pneumoperitoneum at low (6 mm Hg) and higher (10 mm Hg) insufflation pressures were compared. The CO(2) pneumoperitoneum profoundly affected blood gases, acid-base balance, and oxygen homeostasis. Carboxemia with increasing end-tidal CO(2) and partial pressure of CO(2) (p <0.001), acidosis with decreasing pH (p <0.001), and base deficiency with decreasing actual base excess (p <0.001), standard base excess and standard bicarbonate and acid excess with increasing hydrogen bicarbonate (p <0.05 and <0.01) were found. Desaturation (p <0.01) with decreasing oxyhemoglobin p <0.05) and hemoglobin oxygen affinity (p <0.01) were also found. Carboxemia with acidosis was more pronounced with higher (p <0.01) than with lower (p >0.05) intraperitoneal pressures, and also with spontaneous breathing (p <0.05) and superficial ventilation (p <0.001) than with optimal ventilation, resulting in metabolic hypoxemia.
In superficially ventilated and spontaneously breathing rabbits, CO(2) pneumoperitoneum profoundly affected blood gases, acid-base balance, and oxygen homeostasis, resulting in metabolic hypoxemia. With optimal ventilation and low intraperitoneal pressure carboxemia, respiratory acidosis, and changes in oxygen metabolism were minimal.
... Mesothelial cells also actively regulate the exchange with vessels and extracellular spaces by means of gap junctions and vesicular transport. Surprisingly, the intact mesothelial layer also actively inhibits the diffusion of gases such as CO 2 (25,26) and N 2 O (unpublished observations). In women, the peritoneal fluid also contains transudation from growing ovarian follicles, increasing the volume and the concentrations of sex steroid hormones. ...
... This retraction is so rapid that in vivo fixation is necessary to study the intact mesothelial layer. This retraction increases over time (25,26). Identified traumas are mechanical trauma, exposure to a CO 2 pneumoperitoneum (32,33), desiccation, infection, and chemical irritants. ...
... Similarly the decreased bowel motility helps to keep an infection localized. This retraction and the subsequent passive diffusion also explains the increasing resorption of CO 2 (25,26) requiring increasing ventilation during laparoscopic surgery. ...
A surgical trauma results within minutes in exudation, platelets, and fibrin deposition. Within hours, the denuded area is covered by tissue repair cells/macrophages, starting a cascade of events. Epithelial repair starts on day 1 and is terminated by day 3. If repair is delayed by decreased fibrinolysis, local inflammation, or factors in peritoneal fluid, fibroblast growth starting on day 3 and angiogenesis starting on day 5 results in adhesion formation. For adhesion formation, quantitatively more important are factors released into the peritoneal fluid after retraction of the fragile mesothelial cells and acute inflammation of the entire peritoneal cavity. This is caused by mechanical trauma, hypoxia (e.g., CO2 pneumoperitoneum), reactive oxygen species (ROS; e.g., open surgery), desiccation, or presence of blood, and this is more severe at higher temperatures. The inflammation at trauma sites is delayed by necrotic tissue, resorbable sutures, vascularization damage, and oxidative stress. Prevention of adhesion formation therefore consists of the prevention of acute inflammation in the peritoneal cavity by means of gentle tissue handling, the addition of more than 5% N2O to the CO2 pneumoperitoneum, cooling the abdomen to 30°C, prevention of desiccation, a short duration of surgery, and, at the end of surgery, meticulous hemostasis, thorough lavage, application of a barrier to injury sites, and administration of dexamethasone. With this combined therapy, nearly adhesion-free surgery can be performed today. Conditioning alone results in some 85% adhesion prevention, barriers alone in 40%-50%.
... We read with great interest the recently published article by Davarcı et al. [1] in your journal aimed at studying the effects of CO 2 -pneumoperitoneum at 12 mm Hg intraperitoneal pressure on end-tidal CO 2 (P ET CO 2 ) concentration, arterial blood gas values and oxidative stress markers in blood, and bronchial lavage during laparoscopic cholecystectomy using a long protective strategy since our clinical [2] and experimental [3] results were in line with findings of this study [1]. The authors clearly demonstrated significant changes of the peak in respiratory pressure, dynamic lung compliance, P ET CO 2 , arterial pO 2 , pCO 2 , and pH values at the 30th min of CO 2 -pneumoperitoneum in comparison with parameters of both at the baseline and at the end of surgery. ...
... In newborns during laparoscopic surgery, P ET CO 2 value was significantly increased (Figure 1(a)) during the first 20 minutes of CO 2 -pneumoperitoneum at the 7-9 mm Hg of intraperitoneal pressure, which was corrected by mild Figure 1: An impact of CO 2 -pneumoperitoneum on respiratory, blood gases, and oxygen status parameters: (a) the end-tidal CO 2 concentration (P ET CO 2 ) and ventilation rate (VR) parameters in 12 newborns, suffering laparoscopic surgical procedures due to ovarian tumors, at the time of induction (0), at the time of incision (1), and every 10 minutes during (2-9) and after (10) laparoscopic surgery with CO 2 -pneumoperitoneum at 7-9 mmHg (eleven sampling points) from [2], unpublished data); (b) an arterial blood carbon dioxide partial pressure (pCO 2 ), pH, oxyhemoglobin (O 2 Hb), and oxygen tension at half saturation assessing the hemoglobin oxygen affinity (p50): in rabbits without pneumoperitoneum (control), spontaneously breathing animals (series I), superficially ventilated animals (series II), and optimally ventilated animals with insufflation pressures of 10 mmHg (series IIIA) or 6 mmHg (series IIIB). Values are means ± SD (modified from [3]). hyperventilation with increased ventilation rate (VR). ...
... In our experimental studies, all parameters of blood gases, acid base homeostasis, blood oximetry, and oxygen status were monitored in anesthetized and ventilated rabbits as control group, and spontaneously breathing (series I) and superficially (series II) either optimally (series IIIA) ventilated animals with intraperitoneal CO 2 -insuflation at 10 mmHg including an additional subseries with 6 mmHg in optimally ventilated animals (series IIIB), as experimental groups [3]. Changes in blood gases, acid base parameters were clearly shown (Figure 1(b)) during CO 2 -pneumoperitoneum at two levels of intraperitoneal pressure (6 and 10 mm Hg) in different ventilation modes in rabbits, which is an appropriate model for newborns. ...
We read with great interest the recently published article by Davarcı et al. [1] in your journal aimed at studying the effects of CO2-pneumoperitoneum at 12 mm Hg intraperitoneal pressure on end-tidal CO2 (CO2) concentration, arterial blood gas values and oxidative stress markers in blood, and bronchial lavage during laparoscopic cholecystectomy using a long protective strategy since our clinical [2] and experimental [3] results were in line with findings of this study [1]. The authors clearly demonstrated significant changes of the peak in respiratory pressure, dynamic lung compliance, CO2, arterial pO2, pCO2, and pH values at the 30th min of CO2-pneumoperitoneum in comparison with parameters of both at the baseline and at the end of surgery. These changes we considered as consequences of a causative force of CO2-insufflation with increased content of CO2 in the body (rise of CO2 and arterial pCO2), with subsequent mild respiratory or severe acidosis (reduced pH) depending on intraperitoneal pressure rate and CO2-pneumoperitoneum duration [4–6]. Subsequently, the dynamic lung compliance was reduced with increased peak of respiratory pressure in adult patients with ASA I/II [1].
We have monitored respiratory and cardiovascular parameters (systolic/diastolic arterial pressure, heart rate, cardiac output, ventilation rate and pressure, tidal volume, and CO2), the dynamic lung compliance, the peak in respiratory pressure, skin temperature, and urine output with catheter in 12 newborns suffering laparoscopic surgical procedures due to ovarian tumors [2]. All samples were collected at the time of induction, at the time of incision, and every 10 minutes during surgery and after surgery during one and a half hours, subsequently at the eleven time points (0–10). All babies were born at the full term pregnancies with body weight above 3000 g. Anesthesia was induced by Relanium or Midazolam (0,63 ± 0,27 mg/kg/h) and Fentanyl (11,9 ± 5,8 μg/kg/h); pressure controlled mechanical ventilation was done by means of anesthesia-respiratory ventilator (Drager) supplemented with myorelaxants (cisatracurium besilate 0,14 ± 0,05 mg/kg/h or Atracurium 0,54 ± 0,19 mg/kg/h).
In newborns during laparoscopic surgery, CO2 value was significantly increased (Figure 1(a)) during the first 20 minutes of CO2-pneumoperitoneum at the 7–9 mm Hg of intraperitoneal pressure, which was corrected by mild hyperventilation with increased ventilation rate (VR). These changes were accompanied with increased systolic and diastolic arterial blood pressure and decreased cardiac output [2]. Moreover, such parameters as respiratory volume, minute ventilation rate, and dynamic lung compliance were reduced with increased peak of respiratory pressure, whereas heart rate, urine output, and skin temperature were remaining stable [2].
... Over the last decade, our group (for review [11,12]) demonstrated in animal models, rabbits and mainly in a laparoscopic mouse model that peritoneal conditioning decreases CO 2 resorption during surgery [13,14] and the severity of acute inflammation in the entire peritoneal cavity [15] which enhances adhesion formation at surgical trauma sites. This enhancement is mediated by humoral factors in peritoneal fluid since touching small bowels in the upper abdomen [16] can increase adhesions in the lower abdomen. ...
... From animal models we know that irritation of the large mesothelial cells leads to retraction and bulging, exposing the basal membrane and/or the extracellular matrix, to acute inflammation of the entire peritoneal cavity, to increased CO 2 resorbtion [13,14] and to enhanced adhesion formation. The severity of this acute inflammation can be decreased by adding more than 5% of N 2 O [22,23] to the CO 2 pneumoperitoneum, by cooling [24,25] the peritoneal cavity, by preventing desiccation [21], by decreasing blood or fibrin deposition [22] and by the addition of dexamethasone [26]. ...
... The progressively increasing CO 2 resorption during surgery and the lower CO 2 resorption during full-conditioning confirm previous observations in the rabbit model [13,14]. The clinical importance is that occasionally, especially when dissecting the retroperitoneal spaces, CO 2 resorption can increase so rapidly that the intervention has to be interrupted. ...
To translate the concept of full-conditioning (FC) from animal experiments to the human, and to evaluate the efficacy for adhesion prevention. FC consisted of decreasing acute inflammation by 86% CO2+ 10% N2O + 4% O2 for the pneumoperitoneum, cooling of the peritoneal cavity, humidification, heparinized rinsing solution and 5 mg of dexamethasone as demonstrated in animal models.
A randomized controlled trial (RCT: NCT01344486) comparing standard laparoscopy with full conditioning together with a barrier in a 2/3 ratio in 44 women undergoing deep endometriosis surgery at KULeuven. The primary aim was reduction of adhesions. Secondary aims were CO2 resorption, postoperative pain and recovery. Randomization was performed after signing informed consent. Adhesion scoring during second look laparoscopy and pain scoring were done blindly.
In the FC group (n = 16) adhesions were completely prevented in 12/16 women whereas in the control group (n = 11) all women had severe adhesions (P < 0.0005). Also the area, density and severity of adhesions were less. (P <0.001). In the control group, severity, density and area of adhesions were strongly interrelated (P = 0.0001 for all areas) suggesting a common enhancing factor. In the FC group CO2 resorption (P < 0.001), postoperative pain (P < 0.001), and CRP concentrations (P < 0.01) were lower while clinical recovery was faster (P < 0.0001) and time to first flatus (P < 0.002) shorter.In conclusion: This translational research confirms in the human the efficacy of FC in reducing CO2 resorption and adhesions with in addition less postoperative pain, lower postoperative CRP concentrations and an accelerated recovery.
... Based on our experience with rabbit models (Mynbaev et al., 2002a, 2007), we conclude that it is not surprising that CO 2 pneumoperitoneum in itself, without perioperative controlled respiratory support, is enough to cause acidosis in mice, as shown by Bourdel et al. (2007), since absorption of CO 2 through intact and injured tissue (Kazama et al., 1998) as well as during intra-and extra-peritoneal CO 2 insufflations (Mullett et al., 1993) has been clearly demonstrated in both spontaneously breathing and ventilated models (Neto et al., 2000; Mynbaev et al., 2002a, 2007; Bergstrom et al., 2008). ...
... Based on our experience with rabbit models (Mynbaev et al., 2002a, 2007), we conclude that it is not surprising that CO 2 pneumoperitoneum in itself, without perioperative controlled respiratory support, is enough to cause acidosis in mice, as shown by Bourdel et al. (2007), since absorption of CO 2 through intact and injured tissue (Kazama et al., 1998) as well as during intra-and extra-peritoneal CO 2 insufflations (Mullett et al., 1993) has been clearly demonstrated in both spontaneously breathing and ventilated models (Neto et al., 2000; Mynbaev et al., 2002a, 2007; Bergstrom et al., 2008). ...
... The impact of CO 2 -pneumoperitoneum on blood gases (BGs), acid– base balance (ABB) and metabolic parameters has been well studied in smaller (mice, rats) and larger (pigs, dogs, etc.) animals, but the most intelligible mechanism of changes in these parameters was clearly shown in rabbit models. We have also demonstrated that excess amounts of insufflated gas induce changes in BGs and ABB homeostasis (Mynbaev et al., 2002a, b, 2007, in press): during CO 2 pneumoperitoneum , the mesothelial surface CO 2 tension in the abdominal cavity is considerably higher than in both venous and arterial blood. This tension gap makes CO 2 pass into the blood through the parietal peritoneum tissue and the capillaries. ...
... In the superficially ventilated (tidal volume of 6.7 ml/kg and a respiratory rate of 27–29 per min) animals (series A) intraperitoneal pressure was 10 mmHg and in the adequately ventilated (tidal volume of 11.3 ml/kg and a respiratory rate of 18–21 per min) animals (series B) intraperitoneal pressure was 6 mmHg. Ventilation (superficially or adequately) and intraperitoneal pressures were chosen as described (Mynbaev et al., 2002). From these experiments the groups with the most and least pronounced effects of CO 2 pneumoperitoneum were chosen to investigate the effect of the addition of 6% of O 2 . ...
... Berg et al., 1997; Gebhardt et al., 1997), 14 mmHg in dogs (Kotzampassi et al.,1993), and 10 mmHg in pigs (Liem et al., 1996). Our data give a comprehensive picture of changes caused by CO 2 absorption and confirm previous results (Mynbaev et al., 2002). The key event is the progressive accumulation of CO 2 , causing increases in carbonic acids and a base deficit. ...
... To explain why the addition of 6% of O 2 to the CO 2 -pneumoperitoneum does not change HCO 3 -and tCO 2 whereas pCO 2 , pH, ABE, SBE, SBC, pO 2 , sO 2 , O 2 Hb, RHb p50 and lactate are affected is more difficult. Factors that should be taken into consideration include: that CO 2 -pneumoperitoneum finally leads to metabolic hypoxia (Mynbaev et al., 2002) through the Bohr effect and that CO 2 -pneumoperitoneum not only induces mesothelial hypoxia but also causes some hypoxia in the organs of the abdominal cavity. In order to understand the effect of the addition of O 2 to CO 2 on blood gases, acid base and O 2 homeostasis, it could also be compared with the treatment of hypoxia with O 2 . ...
CO(2)-pneumoperitoneum used in endoscopic surgery induces system effects by CO(2) absorption. This study investigated the effect of the addition of O(2) to CO(2)-pneumoperitoneum, upon CO(2) absorption.
The effect of a pneumoperitoneum using 100% CO(2) or 94% CO(2) + 6% O(2) upon arterial blood gases, acid base and O(2) homeostasis was evaluated. In series A suboptimal ventilation and a pneumoperitoneum pressure (PP) of 10 mmHg was used. In series B adequate ventilation and PP of 6 mmHg was used.
CO(2)-pneumoperitoneum profoundly affected blood gases and acid base homeostasis i.e. increasing pCO(2), HCO(3)(P < 0.001) and lactate concentrations (P < 0.05) and decreasing pH, actual base excess and standard bicarbonate (P < 0.001), resulting in metabolic hypoxaemia with desaturation, lower pO(2) (P < 0.001) and O(2)Hb (P < 0.05). These effects were more pronounced with higher PP and suboptimal ventilation.
CO(2)-pneumoperitoneum profoundly affected blood gases and acid base homeostasis resulting in metabolic hypoxaemia. The addition of 6% of O(2) to the CO(2)-pneumoperitoneum prevented these effects to a large extent. If these preliminary data are confirmed in the human, the addition of a few percent of O(2) to CO(2) could become important for endoscopic surgery of long duration, especially in obese patients with limited cardiorespiratory adaptation and steep Trendelenburg.
... Other systematic effects produced by the CO 2 -induced pneumoperitoneum are the CO 2 absorption from the abdominal cavity, causing acidosis and hypercarbia [31][32][33][34][35], which, if not compensated adequately for ventilation, can negatively affect the cardiovascular and respiratory functions [35,36]. Moreover, CO 2 -induced pneumoperitoneum impairs venous return, depending on the intra-abdominal pressure [37], and decreases splanchnic perfusion with resulting oxidative stress [38]. ...
... Adhesion formation was higher in animals poorly ventilated and decreased with higher ventilation rates. In comparison with animals that underwent anaesthesia only, the CO 2induced pneumoperitoneum increases the pCO 2 and decreases the pH, as has been reported in animal models [31,34,155] and humans [36]. These effects were more pronounced in poorly ventilated mice and counteracted by appropriate ventilation (i.e. higher ventilation rates). ...
The peritoneum is the serous membrane that covers the abdominal cavity and most of the intra-abdominal organs. It is a very delicate layer highly susceptible to damage and it is not designed to cope with variable conditions such as the dry and cold carbon dioxide (CO2) during laparoscopic surgery. The aim of this review was to evaluate the effects caused by insufflating dry and cold gas into the abdominal cavity after laparoscopic surgery.
A literature search using the Pubmed was carried out. Articles identified focused on the key issues of laparoscopy, peritoneum, morphology, pneumoperitoneum, humidity, body temperature, pain, recovery time, post-operative adhesions and lens fogging.
Insufflating dry and cold CO2 into the abdomen causes peritoneal damage, post-operative pain, hypothermia and post-operative adhesions. Using humidified and warm gas prevents pain after surgery. With regard to hypothermia due to desiccation, it can be fully prevented using humidified and warm gas. Results relating to the patient recovery are still controversial.
The use of humidified and warm insufflation gas offers a significant clinical benefit to the patient, creating a more physiologic peritoneal environment and reducing the post-operative pain and hypothermia. In animal models, although humidified and warm gas reduces post-operative adhesions, humidified gas at 32 °C reduced them even more. It is clear that humidified gas should be used during laparoscopic surgery; however, a question remains unanswered: to achieve even greater clinical benefit to the patient, at what temperature should the humidified gas be when insufflated into the abdomen? More clinical trials should be performed to resolve this query.
... Adhesions formation was higher in animals poorly ventilated and decreased with higher ventilation rates (ml/min). In comparison with animals who underwent anaesthesia only, the CO 2 pneumoperitoneum increases the pCO 2 and decreases the pH, as has been reported in pigs (liem et al., 1996), dogs (Kotzampassi et al., 1993), rabbits (Mynbaev et al., 2002), rats (Hazebroek et al., 2002a) and humans (neuberger et al., 1996). These effects were more pronounced in mice poorly ventilated and counteracted by appropriate ventilation (i.e., higher ventilation rates). ...
... The mechanism whereby this acidosis/hypercarbia becomes a cofactor in adhesion formation remains unclear. CO 2 pneumoperitoneum induces respiratory acidosis that, if not corrected, leads to metabolic acidosis and metabolic hypoxia (Mynbaev et al., 2002). This could enhance the ischemic hypoxia in the peritoneum, which was suggested to be a driving mechanism in CO 2 pneumoperitoneum-enhanced adhesion formation. ...
In spite of the approaches that have been proposed to reduce postoperative peritoneal adhesions, they remain a major clinical problem because of the associated intestinal obstruction, chronic pelvic pain, female infertility and difficulties at the time of reoperation. The pathogenesis of the process have been focused almost exclusively on the local events induced by the surgical trauma, and the strategies for adhesion prevention thus focused on barriers to separate surgically denuded areas. The important role of the peritoneal cavity environment only recently became apparent and is not yet incorporated in adhesion reducing strategies. Recent data demonstrate that, in the presence of a direct surgical trauma, the entire peritoneal environment is quantitatively the most important factor in adhesion formation and hence adhesion prevention after both open and laparoscopic surgery. Indeed mesothelial hypoxia (CO2 pneumoperitoneum) or hyperoxia (open surgery), desiccation and surgical manipulation have been identified as factors cumulatively enhancing adhesions--. The clinical implication is especially relevant for laparoscopic surgery because the pneumoperitoneum, being a closed environment, can be easily conditioned. Although human studies are lacking, animal data indicate that peritoneal adhesions can be reduced by over 80% with a good surgical technique, with adequate pneumoperitoneum conditioning as adding 3-4% of oxygen to the CO2 pneumoperitoneum, prevention of desiccation and slight cooling. Adhesion prevention barriers remain additionally effective, although quantitatively less important. The relevance of all these strategies for adhesion prevention still have to be confirmed in humans, but since it seems that the peritoneal environment is quantitatively much more important than the surgical trauma, adhesion prevention research and strategies should be directed more to conditioning the peritoneal cavity than to the use of agents.
... 1,2 We have already shown that intra-abdominal CO 2 insufflation profoundly affects blood gases, acidebase balance, and oxygen homeostasis, resulting in metabolic hypoxemia. 3 The effect of this strictly depends on respiratory parameters (tidal volume and rate of ventilation) and depth of anesthesia, where spontaneous breathing appears to be more harmful than optimally controlled ventilation (unpublished data; Fig. 1). In our experiments, the control group includes animals without CO 2 pneumoperitoneum, Figure 1. ...
... In our experiments, the respiratory parameters were precisely calculated for each rabbit according to its individual weight. Subsequently, severe blood gas and acidebase changes were accompanied by decreased blood oximetry parameters (sO 2 ), increased parameters of oxygen tension at half saturation (p50), 3 and lactate values in suboptimally ventilated animals (see Fig. 1). According to these results, we suggest that raised arterial lactate values due to mesothelium hypoxia and local acidosis during intra-abdominal CO 2 insufflation depends on ventilation modes. ...
... In rabbits undergoing mild CO 2 pneumoperitoneum (6e10 mm Hg), they showed that optimal mechanical ventilation reduced the pH and CO 2 Bohr effects on hemoglobin, thereby maintaining adequate arterial oxygen saturation and tissue oxygenation. 1 We agree with Dr. Mynbaev and colleagues that optimal ventilation is important in experimental animal research, and, as they noted in our study of severe CO 2 pneumoperitoneum (30 mmHg), the pigs were slightly hyperventilated at baseline (arterial pCO 2 of 3.9e4.1 kPa) and became hypercapnic to some extent (arterial Pco 2 of 5.7e6.4 kPa) throughout the experiment. 2 We believe however that the main results (increased intraperitoneal lactate/pyruvate ratio and glycerol levels at intra-abdominal hypertension [IAH] and normalization of the former after decompression) are independent of CO 2 . ...
... We read with interest the article by Chiu et al. on three different methods of ultrasound (US) measurement of abdominal aortas: inner-to-inner (ITI), outer-to-outer (OTO), and leading edge to leading edge (LTL). 1 The authors showed OTO measurement was the most accurate, and claim inter-and intra-observer variability was superior for OTO but not statistically significant. Statistical values have been omitted preventing assessment of data quality. ...
... We read with great interest the article by Qin et al. (1). because the physiological aspects of pneumoperitoneum belong to our research subjects (2,3). Although we congratulate the authors for the randomized trial, it seems that their study design and results are raising several questions. ...
... The absorption of CO 2 is also related to excess IPP. This results in hypercarbia and systemic metabolic acidosis, leading to decreased haemoglobin O 2 affinity and decreased O 2 availability in tissues [44]. High IPP have been shown to cause peritoneal hypoxia compared to lower IPP with CO 2pneumoperitoneum [42,43]. ...
In this article the adverse effects of laparoscopic CO2 pneumoperitoneum and coelomic climate change, and their potential prevention by warmed, humidified carbon dioxide insufflation are reviewed. The use of pressurized cold, dry carbon dioxide (C02) pneumoperitoneum causes a number of local effects on the peritoneal mesothelium, as well as systemic effects. These can be observed at a macroscopic, microscopic, cellular and metabolic level. Local effects include evaporative cooling, oxidative stress, desiccation of mesothelium, disruption of mesothelial cell junctions and glycocalyx, diminished scavenging of reactive oxygen species, decreased peritoneal blood flow, peritoneal acidosis, peritoneal hypoxia or necrosis, exposure of the basal lamina and extracellular matrix, lymphocyte infiltration, and generation of peritoneal cytokines such as IL-1, IL-6, IL-8 and TNFα. Such damage is increased by high CO2 insufflation pressures and gas velocities and prolonged laparoscopic procedures. The resulting disruption of the glycocalyx, mesothelial cell barrier and exposure of the extracellular matrix creates a cascade of immunological and pro-inflammatory events and favours tumour cell implantation. Systemic effects include cardiopulmonary and respiratory changes, hypothermia and acidosis. Such coelomic climate change can be prevented by the use of lower insufflation pressures and preconditioned warm humidified CO2. By achieving a more physiological temperature, pressure and humidity, the coelomic microenvironment can be better preserved during pneumoperitoneum. This has the potential clinical benefits of maintaining isothermia and perfusion, reducing postoperative pain, preventing adhesions and inhibiting cancer cell implantation in laparoscopic surgery.
... In addition to regulating transport of fluid, substances, and gases between the peritoneal cavity and plasma, the mesothelial cell facilitates gliding of moving organs such as bowels (and lungs and heart). Active regulation or inhibition of gas transport by the mesothelial cell is unexpected and unexplained, but it is the only hypothesis that can explain the observation that during CO 2 pneumoperitoneum in both humans and rabbits (Mynbaev et al. 2002a) the resorption of CO 2 increases progressively over time and that this increase is prevented by keeping the mesothelial layer intact through conditioning , Mynbaev et al. 2002b). In addition, intact mesothelial cells actively prevent the diffusion of nitrous oxide (N 2 O) through the mesothelial layer since during N 2 O anesthesia no N 2 O can be measured in the pneumoperitoneum, and during pneumoperitoneum with 100% N 2 O no N 2 O can be measured in the lungs (Mulier & Van Acker, personal communication, 2012). ...
The consequences of pelvic surgery can include postoperative pain, adhesion formation, a recovery period, and postoperative fatigue. For the same intervention, laparoscopic surgery is considered superior to laparotomy since it is associated with less pain, a faster recovery, a shorter hospitalization period, and a more aesthetic scar. Laparoscopic surgery moreover is also believed to be less adhesio-genic because the magnification of the surgical field and smaller instruments would permit a more precise surgery. This chapter will present a mix of experimental data from animal models and observational medicine. We will emphasize the central role that acute inflammation of the peritoneal cavity plays in postoperative pain, adhesion formation, recovery, and fatigue. This should illuminate the pathophysiology of healing and recovery and thus aid in prevention of undesirable effects. In addition, this will highlight the differences between surgery by laparoscopy and by laparotomy, which requires a large incision in the abdominal wall. The role of the peritoneal cavity might also give a glimpse of the future directions of surgery both for the patient's benefit and for the health care costs. These include both the direct costs of surgery and analgesics; and the indirect costs of recovery, fatigue, absence from work; and the costs related to adhesion formation such as chronic pain, infertility, reoperation, and possibly ovarian damage and tumor metastasis.
... We have read the article by Shoar et al 1 with great interest, which comparatively evaluated a systemic stress response between low-pressure and standard pressure pneumoperitoneum (LPP vs SPP) during laparoscopic cholecystectomy (LC) in a prospective, double-blinded randomized controlled trial, since this multidisciplinary topic has been a research project of our international research team for several years 2,3 . ...
Corresponding author. The International Translational Medicine & Biomodeling Research Team, Laboratory of Human Physiology, Moscow Institute of Physics & Technology (State University), Dolgoprudny, Moscow region, Russia.
... It is well known that routinely used pressures during robotic hysterectomy and other urogenital procedures are about 8-15 mmHg [2] and mostly higher than 10 mmHg [3,4], whereas a raised CO 2 insufflation pressure is associated with blood gas acid base disturbances followed by acidemia and a linearly increased partial CO 2 pressure and decreased pH lead to metabolic hypoxemia [5]. ...
... We previously demonstrated that reduced blood gas changes during CO 2 pneumoperitoneum are associated with mixed gas insufflation (MGI) since even a small concentration of O 2 added to CO 2 results in lower end tidal CO 2 (P ET CO 2 ) values and slight changes in blood gas parameters in comparison with those of pure CO 2 insufflation in rabbits [2,3]. Also, MGI has a significant impact on ventilation parameters [4]. Subsequently, it is obvious that during surgery, patients in the FC group require less increased tidal volume (TV) and lower ventilation frequency than patients in the standard pneumoperitoneum group. ...
No abstract available.
... This model combines two approaches developed for tissue-blood CO 2 exchange [1] and CO 2 excretion by lungs [2]. Initially we have developed a rabbit model and validated it by a wide range of available experimental data [3]. After that a human model is established. ...
Carbon dioxide (CO2) is a highly diffusible gas easily soluble in water and blood. CO2 is rapidly
excreted through the lungs therefore it widely applied for medical needs. CO2-pneumoperitoneum
is the leverage to perform laparoscopic surgical manipulations. Potential side-effects of excessive CO2 insufflated during laparoscopy are vanished in healthy individuals by means of pressure- or/and volume-controlled ventilation.
However, nowadays laparoscopic procedures are widely used by continuously providing new indication areas, involving different type of patients populations, including children, obese individuals and subjects with respiratory, cardiovascular and hematological diseases. Subsequently, CO2-pneumoperitoneum side-effects could produce potentially harmful consequences particularly in these high risk patients as well as with application of the state of the art technologies in surgical fields, e.g. robotic or telesurgery, when high CO2-pneumoperitoneum pressure used to make properly view for remote surgeons. A set of mathematical models is proposed for simulating CO2 balance in organism during CO2-pneumoperitoneum allowing optimization of artificial ventilation parameters (frequency and tidal volume) as a function from CO2-pneumoperitoneum pressure and individual features of a particular patient.
... Increased intracranial pressure enhances the sympathetic outflow by distension of the cerebral arteries. In fact, the upward compression of the diaphragm causes an increased intra-thoracic pressure and elevated central venous pressure, ultimately leading to intra-cranial hypertension (30). ...
Abstract Background: Myomectomy is one of the most common surgical procedures in gynecology and has implications on fertility and subsequent pregnancies. We compared the impact of surgical approach on blood loss during laparoscopic and abdominal intracapsular myomectomy. Material and methods: The evaluation comprised 124 fertile women with subserous or intramural myomas: 66 patients treated by laparoscopy and 58 patients treated by laparotomy. The intracapsular myoma enucleation technique was similar for both approaches. All procedures were analyzed for the evaluation of intra- and post-surgical blood loss and intra- and short-term post-operative surgical outcomes. Results: The operating time for laparoscopic intracapsular myomectomy was longer (95 ± 7.2 min vs. 63 ± 5.6, p < 0.0001), but was associated with reduced intra- (65 ± ml vs. 105 ± 5, p < 0.0001) and post-surgical blood loss (30 ± 5 vs. 60 ± 5 ml, p < 0.0001), as well as diminished application of pain relief medication (8 patients vs. 17, p < 0.05), compared to open intracapsular myomectomy. Conclusions: The surgical approach did not substantially affect the technique of intracapsular myomectomy; however, laparoscopy significantly reduced intra- and postoperative blood loss and resulted in better short-term outcomes than after open surgery. Our results underscore the advantages of trying to reduce the rate of laparotomic myomectomy, one of the leading surgical interventions associated with infertility and sterility.
... However, laparoscopic surgery entails other, specific effects due to the use of gas media to extend the abdomen . From this, a large body of literature has sprung studying the pathophysiologic mechanisms of CO 2 pneumoperitoneum induced systemic alterations such as respiratory, cardiovascular and blood gas, acid base parameters changes, as well as local disturbances in the peritoneal cavity such as decreased peritoneal pH and blood circulatory deteriorations with mesothelial hypoxemia during laparoscopic surgery242526272829 . The discussion has polarised: some claim these changes have a crucial impact on postsurgical complications such as adhesion formation and port-site cancer metastasis3031323334 others say these changes have no or little impact on postsurgical complications [16,17,28,29]. ...
Many factors have been put forward as a driving mechanism of surgery-triggered adhesion formation (AF). In this study, we underline the key role of specific surgical trauma related with open surgery (OS) and laparoscopic (LS) conditions in postoperative AF and we aimed to study peritoneal tissue inflammatory reaction (TIR), remodelling specific complications of open surgery (OS) versus LS and subsequently evaluating AF induced by these conditions.
A prospective randomized study was done in 80 anaesthetised female Wistar rats divided equally into 2 groups. Specific traumatic OS conditions were induced by midline incision line (MIL) extension and tissue drying and specific LS conditions were remodelled by intraperitoneal CO2 insufflation at the 10 cm of water. TIR was evaluated at the 24th, 72nd, 120th and 168th hour by scoring scale. Statistical analysis was performed by the non-parametric t test and two-way ANOVA using Bonferroni post-tests.
More pronounced residual TIR was registered after OS than after LS. There were no significant TIR interactions though highly significant differences were observed between the OS and LS groups (p < 0.0001) with regard to surgical and time factors. The TIR change differences between the OS and LS groups were pronounced with postoperative time p < 0.05 at the 24th and 72nd; p < 0.01--120th and p < 0.001--168th hrs. Adhesion free wounds were observed in 20.0 and 31.0% of cases after creation of OS and LS conditions respectively; with no significant differences between these values (p > 0.05). However larger adhesion size (41.67 ± 33.63) was observed after OS in comparison with LS (20.31 ± 16.38). The upper-lower 95% confidential limits ranged from 60.29 to 23.04 and from 29.04 to 11.59 respectively after OS and LS groups with significant differences (p = 0.03). Analogous changes were observed in adhesion severity values. Subsequently, severe TIR parameters were followed by larger sizes of severe postoperative adhesions in the OS group than those observed in the LS group.
MIL extension and tissue drying seem to be the key factors in the pathogenesis of adhesion formation, triggering severe inflammatory reactions of the peritoneal tissue surrounding the MIL resulting in local and systemic consequences. CO2 insufflation however, led to moderate inflammation and less adhesion formation.
... At present, therefore, it is unclear whether the type of insufflation gas is an important variable in the mechanisms giving rise to PSM. It is clear, however, that CO 2 pneumoperitoneum induces more pronounced physiological changes such as peritoneal acidosis which seems to be independent from systemic pH and may well alter the microenvironment of the cancer cell-mesothelial interaction [54][55]. ...
The persistence of residual tumour is associated with the histology and stage of the primary cancer, the completeness and quality of surgery, and postoperative events such as anastomotic leakage or entrapment of cells in exudating wound surfaces. At present, there is no clinical evidence that the use of laparoscopic techniques adversely influences the risk of residual disease. The inflammatory process associated with surgery shares a number of central mediators and pathways with tumour growth and invasiveness. Both cellular components (mainly macrophages and fibroblasts) and humoral factors associated with inflammation have been shown to enhance tumour growth in numerous preclinical studies. Tumour foci at a distance from the main cancer are kept in a dormant state by a range of anti-angiogenic mediators produced by the main cancer. Preclinical studies have shown that removal of the primary cancer reactivates proliferative and metastatic pathways in the residual tumour. Clinically, this phenomenon has been proposed as underlying the observed rapid systemic relapse after surgery in young node positive breast cancer patients. Strategies proposed to prevent residual disease encompass avoidance of tumour spill and minimization of surgical trauma and related inflammation. Efforts to remove or kill free intraperitoneal cells by local antiseptic or cytotoxic regimens have met only limited clinical success. Specific targeted therapy aimed at inhibiting the inflammatory response, tumour cell adhesion, or the metastatic phenotype of dormant cells appears promising in preclinical models and needs to be addressed in future clinical trials.
Transport of respiratory gases by respiratory and circulatory systems is one of the most important processes associated with living conditions of the human body. Significant and/or long-term deviations of oxygen and carbon dioxide concentrations from the normal values in blood can be a reason of significant pathological changes with irreversible consequences: lack of oxygen (hypoxia and ischemic events), the change in the acidbase balance of blood (acidosis or alkalosis), and others. In the context of a changing external environment and internal conditions of the body the action of its regulatory systems aimed at maintaining homeostasis. One of the major mechanisms for maintaining concentrations (partial pressures) of oxygen and carbon dioxide in the blood at a normal level is the regulation of minute ventilation, respiratory rate and depth of respiration, which is caused by the activity of the central and peripheral regulators.
In this paper we propose a mathematical model of the regulation of pulmonary ventilation parameter. The model is used to calculate the minute ventilation adaptation during hypoxia and hypercapnia. The model is developed using a single-component model of the lungs, and biochemical equilibrium conditions of oxygen and carbon dioxide in the blood and the alveolar lung volume. A comparison with laboratory data is performed during hypoxia and hypercapnia. Analysis of the results shows that the model reproduces the dynamics of minute ventilation during hypercapnia with sufficient accuracy. Another result is that more accurate model of regulation of minute ventilation during hypoxia should be developed. The factors preventing from satisfactory accuracy are analysed in the final section.
Respiratory function is one of the main limiting factors of the organism during intense physical activities. Thus, it is important characteristic of high performance sport and extreme physical activity conditions. Therefore, the results of this study have significant application value in the field of mathematical modeling in sport. The considered conditions of hypoxia and hypercapnia are partly reproduce training at high altitude and at hypoxia conditions. The purpose of these conditions is to increase the level of hemoglobin in the blood of highly qualified athletes. These conditions are the only admitted by sport committees.
CO2-pneumoperitoneum disinflation is a triggering factor of a postsurgical oxidative stress.
Abstract Background: Myomectomy is one of the most common surgical procedures in gynecology and has implications on fertility and subsequent pregnancies. We compared the impact of surgical approach on blood loss during laparoscopic and abdominal intracapsular myomectomy. Material and methods: The evaluation comprised 124 fertile women with subserous or intramural myomas: 66 patients treated by laparoscopy and 58 patients treated by laparotomy. The intracapsular myoma enucleation technique was similar for both approaches. All procedures were analyzed for the evaluation of intra- and post-surgical blood loss and intra- and short-term post-operative surgical outcomes. Results: The operating time for laparoscopic intracapsular myomectomy was longer (95 ± 7.2 min vs. 63 ± 5.6, p < 0.0001), but was associated with reduced intra- (65 ± ml vs. 105 ± 5, p < 0.0001) and post-surgical blood loss (30 ± 5 vs. 60 ± 5 ml, p < 0.0001), as well as diminished application of pain relief medication (8 patients vs. 17, p < 0.05), compared to open intracapsular myomectomy. Conclusions: The surgical approach did not substantially affect the technique of intracapsular myomectomy; however, laparoscopy significantly reduced intra- and postoperative blood loss and resulted in better short-term outcomes than after open surgery. Our results underscore the advantages of trying to reduce the rate of laparotomic myomectomy, one of the leading surgical interventions associated with infertility and sterility.
To evaluate the metabolic consequences of the addition of oxygen to the CO(2)-pneumoperitoneum.
Prospective randomized study in rabbits. After 30 minutes of ventilation pneumoperitoneum was maintained for 90 minutes with pure CO(2) or CO(2) with 2% or 6% of oxygen. The intraperitoneal pressure was increased from 10 to 15 and 20 mm Hg every 30 minutes. Ventilation rate was either fixed or a progressive hyperventilation. End points were changes in arterial blood gases (Pco(2), Po(2)), pH, acid-base balance (actual base excess [ABE], standard bicarbonate [SBC], standard base excess [SBE], hydrogen carbonate [HCO(3)(-)], concentration of total carbon dioxide [Tco(2)]); oxygen and oximetry (oxyhemoglobin [O(2)Hb], oxygen saturation [So(2)], reduced hemoglobin [RHb], total oxygen concentration [To(2)], and oxygen tension at half saturation assessing hemoglobin oxygen affinity [p50]); and lactate concentrations assayed every 15 minutes.
University research center.
Twenty-four adult female New Zealand white rabbits.
Anesthesia, mechanical ventilation, and pneumoperitoneum.
The effects of CO(2)-pneumoperitoneum on all end points increased with the elevated intraperitoneal pressure and were more pronounced when ventilation was fixed. Changes were less when 2% or 6% of oxygen had been added to the CO(2)-pneumoperitoneum. With use of logistic regression, the addition of oxygen, intraperitoneal pressure, and ventilation were found to be independent variables affecting Pco(2), pH, ABE, SBE, HCO(3)(-), O(2)Hb, So(2), p50, and end-tidal CO(2).
The metabolic consequences of the combined effect of increased intraperitoneal pressure and CO(2)-pneumoperitoneum were less when 2% to 6% of oxygen was added or when animals were hyperventilated. We suggest that metabolic and mesothelial hypoxemia caused by CO(2) absorption can be reduced by adding small amounts of oxygen and by hyperventilation.
The effect of assisted ventilation and CO(2) pneumoperitoneum during laparoscopic surgery upon blood gases and adhesion formation were evaluated in mice. We confirmed that the CO(2) pneumoperitoneum induces acidosis and enhances adhesion formation, and an association between both effects was demonstrated, together with its modulation by the assisted ventilation.
Peritoneal absorption of CO(2) during abdominal insufflation in laparoscopy may disrupt the acid-base equilibrium and alter the physiological response to stress. Current nonventilated rodent models of laparoscopy do not manage the CO(2) load of pneumoperitoneum, but ventilated surgical rodent models are invasive (tracheotomy) and may independently induce the inflammatory response.
A comprehensive rodent model of laparoscopy was developed. Rats were randomized to receive anesthesia alone, anesthesia plus CO(2) pneumoperitoneum, or anesthesia plus CO(2) pneumoperitoneum with videoendoscopic intubation and mechanical ventilation. Arterial blood-gas analysis was performed at baseline and after 30 min of intervention.
Baseline pH, pCO(2), and HCO(3)(-) arterial blood gas parameters were normal for all rats. After 30 min, pCO(2) and pH changed slightly but remained normal among rats receiving anesthesia alone (pCO(2) = 46.5 +/- 1.9; pH = 7.365 +/- 0.009) whereas animals receiving anesthesia plus CO(2) pneumoperitoneum that were dependent on spontaneous respiration for ventilation developed significant hypercarbic acidosis (pCO(2) = 53.2 +/- 1.9, P < 0.05; pH = 7.299 +/- 0.011, P < 0.001). This acidosis was completely corrected with increased minute ventilation in intubated rats receiving mechanical ventilation (pCO(2) = 36.8 +/- 1.5, P < 0.001; pH = 7.398 +/- 0.011, P < 0.001).
CO(2) pneumoperitoneum induces significant hypercarbic acidosis in nonventilated rats. Noninvasive endotracheal intubation is feasible in the rat with videoendoscopic assistance. Our noninvasive rodent model of laparoscopic surgery controls for anesthesia- and capnoperitoneum-related acid-base changes and provides an environment in which the biological response to pneumoperitoneum can be studied precisely.
Postoperative adhesion development remains a very frequent occurrence, which is often unrecognized by surgeons because of limited ability to conduct early second-look laparoscopies. The consequences include infertility, pelvic pain, bowel obstruction, and difficult reoperative procedures. To date, approaches to limit adhesions primarily have involved barriers to separate tissue during reepithelization. Future progress in regulating adhesion development and tissue fibrosis likely will require an improved understanding of the molecular processes involved in normal peritoneal repair and its aberrations leading to adhesion development. We hypothesize that tissue hypoxia (in part resulting from tissue incision, fulguration, suture ligation, etc.) is the major inciting event, which leads to a coordinated series of molecular events that promote an inflammatory response leading to enhanced tissue fibrosis. These events are reduced plasminogen activator activity, extracellular matrix deposition, increased cytokine production, increased angiogenesis, and reduced apoptosis (programmed cell death). Improved understanding of these events and their regulation will provide the opportunity to regulate better postoperative adhesion development and tissue fibrosis, thereby reducing the morbidity and mortality they cause.
To investigate the effects of hypoxia-inducible factor (HIF) inhibitors, flotation agents, barriers, and a surfactant on pneumoperitoneum-enhanced adhesions in a laparoscopic mouse model.
Prospective randomized trial (Canadian Task Force classification I).
Department of Obstetrics and Gynecology, University Hospital Gasthuisberg, Catholic University of Leuven.
One hundred fourteen female BALB/c mice.
Adhesions were induced during laparoscopy in BALB/c female mice. Pneumoperitoneum was maintained for 60 minutes with humidified CO(2). In 3 experiments the effects of HIF inhibitors such as 17-allylamino 17-demethoxygeldanamycin, radicicol, rapamycin, and wortmanin, flotation agents such as Hyskon and carboxymethylcellulose, barriers such as Hyalobarrier gel and SprayGel, and surfactant such as phospholipids were evaluated.
Adhesions were scored after 7 days during laparotomy. Adhesion formation decreased with the administration of wortmannin (p <.01), phospholipids (p <.01), Hyalobarrier Gel (p <.01), and SprayGel (p <.01).
These experiments confirm the efficacy of barriers and phospholipids to separate or lubricate damaged surfaces. They also confirm the role of mesothelial hypoxia in this model by the efficacy of the HIF inhibitor wortmannin.
The effect of laparoscopic cholecystectomy on cardiopulmonary and endocrinological parameters results from various factors such as increased intraabdominal pressure (IAP), CO2, and the positioning. However, positioning has not yet been regarded. Reliable examination of the individual influencing factors requires standardized anesthesiological procedure and constant IAP. Presently, the effect of positioning is observed separately from those effects caused by the pneumoperitoneum with CO2 (PP) under standardized conditions.
40 patients with no history of cardiopulmonary disease were analyzed. Preoperative medication, induction and management of general anesthesia, positioning of the patient and IAP (12 mmHg) were standardized. Hemodynamic, respiratory and endocrinological parameters were determined with the patient in a supine position and in the position typical for the procedure (15 degrees head-down and 10 degrees slant to the left), each with and without PP. Heart rate (ECG), endexpiratory pCO2 (peECO2), invasive blood pressure (radial art.), central venous pressure, partial arterial O2 saturation (psaO2), and ventilation pressures (peak, plateau) were monitored throughout anesthesia. The parameters pH, pCO2, BE, HCO3-, COHb, vasopressin, lactate, and ammonia were analysed in arterial and venous blood samples at predetermined set points: base line, 10 min after CO2 insufflation, 10 min after desufflation, and 1 h after extubation (cf. table 1). Statistical analysis was performed using the Wilcoxon-test with p < or = 0.05 considered statistically significant.
Insufflation of CO2 lead to a 12% increase of heart rate in supine position and to even 18% in the position required for surgery. Same significant changes were observed for arterial blood pressure (21 or respectively 28%). Central venous pressure increased by more than 200% after CO2 insufflation. Endexpiratory pCO2 increased by 2.4 mmHg after CO2 insufflation in the supine position and by 5 mmHg in the surgical position. Ventilation pressures increased significantly by 16%. Analysis of the effect of PP on blood gases showed that pH decreased from 7.47 to 7.43, and arterial pCO2 increased by 5.1 mmHg to 38.7 mmHg and increased further after desufflation to values of up to 43.9 mmHg. Arterial pO2 decreased steadily (18% after insufflation). Vasopressin plasma levels increased exponentially from 3.03 to maximal values of 104.45 pg/ml. Ammonia and lactate showed the expected, nearly identical course. Lactate increased within the clinically and methodically irrelevative range, from 1.12 to 1.159 mmol/l. Ammonia decreased by 29%.
The observed changes, i.e. heart rate, central venous pressure, and arterial blood pressure are caused and altered by CO2 insufflation and the various positioning of patients. The increased vasopressin concentration more than likely contributes to these changes. The query whether the position of the patient also causes a change in respiratory parameters and blood gas analysis cannot be differentiated except for the end-tidal pCO2. Inspite of the observed changes no cardiopulmonary complications occurred in this patient group. Therefore, it seems possible to omit invasive monitoring in cardiopulmonary healthy patients. In patients with concomitant history of cardiopulmonary disease, however, deteriorations due to laparoscopy should be thoroughly taken into consideration and studied further.
Our aim was to investigate the feasibility of a mouse model to study adhesion formation following endoscopic surgery. Following
preliminary studies to establish anaesthesia and pneumoperitoneum pressure, a prospective randomized study was carried out
to investigate the effect of CO2 pneumoperitoneum on postoperative adhesions. In group I (control group), the duration of pneumoperitoneum was shorter than
5 min. In groups II, III and IV, pneumoperitoneum was maintained for 60 min without flow, with a continuous low flow (1 ml/min)
and a continuous high flow (10 ml/min) through the abdominal cavities of the mice using non-humidified CO2, respectively. Adhesions were scored after 7 days by laparotomy. The total adhesion scores were 0.9 ± 0.8 (n = 15) in control group, 2.4 ± 0.8 (n = 15) (P < 0.001 versus control group) in group II with no flow, 2.6 ± 1.3 (n = 15) (P < 0.001 versus control group) in group III with a continuous low flow and 4.3 ± 0.9 (n = 15) (P < 0.001 versus control group and P < 0.001 versus group II and III) in group IV with a continuous high flow. In conclusion, the mouse can be used as a model
to study adhesion formation following endoscopic surgery. Duration of CO2 pneumoperitoneum is a co-factor in adhesion formation.
The aim of the study was to test the hypothesis that the increase in adhesion formation by CO2 pneumoperitoneum is caused by mesothelial hypoxaemia. Therefore the effect of the intra-abdominal pressure together with
the flow rate upon adhesion formation was evaluated in rabbits following laser and bipolar lesions during endoscopic surgery
using humidified CO2 at 35 ± 1°C. The intra-abdominal pressure and flow rate were 5 mmHg and 1 l/min in group 1 (n = 5), 5 mmHg and 10 l/min in group 2 (n = 4), 20 mmHg and 1 l/min in group 3 (n = 5) and 20 mmHg and 10 l/min in group 4 (n = 4) respectively. A rapid and reliable intubation method for rabbits was developed to permit high insufflation pressure.
By two-way analysis of variance, total adhesion scores following a laser lesion increased with flow rate (P = 0.0003) and insufflation pressure (P = 0.002). Total adhesion scores of bipolar lesions increased with pressure (P = 0.02) but not with flow rate (P = 0.1). The total adhesion scores of laser and bipolar lesions together increased with flow rate (P = 0.005) and with insufflation pressure (P = 0.004). There was no statistical interaction between flow rate and insufflation pressure. In conclusion, the insufflation
pressure in endoscopic surgery with CO2 pneumoperitoneum is a co-factor in adhesion formation, together with desiccation.
A prospective randomized trial in a rabbit model was performed to test the hypothesis that the increase in adhesion formation following prolonged pneumoperitoneum is mediated by peritoneal hypoxaemia. Laparoscopic standardized opposing lesions were performed in uterine horns and pelvic sidewalls by bipolar coagulation and CO(2) laser in six groups of eight animals. Pure CO(2) or helium pneumoperitoneum was used for 10 (groups I and IV) or 45 min (groups II and V) to confirm the effect of duration of pneumoperitoneum and 96% of CO(2) or helium with 4% of oxygen (group III and VI) for 45 min to assess the effect of the addition of oxygen. After 7 days, adhesion formation was scored by laparoscopy. By two-way analysis of variance, total, extent, type and tenacity of adhesion scores increased (P = 0.0003, P = 0.0004, P = 0.0004 and P = 0.004) with increasing duration of pneumoperitoneum and decreased (P = 0.02, P = 0.03, P = 0.01 and P = 0.05) with the addition of oxygen. No differences were found between CO(2) and helium. In conclusion these data confirm the effect of pneumoperitoneum upon adhesions and demonstrate its reduction by oxygen, strongly suggesting that the main cause of adhesion formation is the relatively superficial hypoxaemia produced by the pneumoperitoneum.
This study evaluated the effects of high-frequency oscillation (HFO) and conventional mechanical ventilation (CMV) on gas exchange and the pulmonary surfactant system in an acute lung injury model. Following induction of lung injury with N-nitroso-n-methylurethane, adult rabbits were anesthetized and randomized to one of the following ventilatory strategies: HFO for 120 min, CMV for 120 min, HFO for 60 min, followed by CMV for 60 min, CMV for 60 min followed by HFO for 60 min or CMV for 60 min. Separate animals were ventilated using CMV with a lower tidal volume and a positive end-expiratory pressure level that was increased throughout the experimental period. Oxygenation was significantly greater in animals ventilated with HFO compared with animals ventilated with CMV. The proportion of surfactant in large aggregate forms was significantly greater following ventilatory support with HFO compared with CMV. Surfactant aggregate conversion was also significantly lower during HFO compared with CMV. We conclude that in our model of acute lung injury, HFO was a superior mode of ventilation and reduced the conversion of alveolar surfactant large aggregates into small aggregate forms, resulting in a greater percentage of large aggregate forms in the alveolar space.
An investigation of end-tidal carbon dioxide tension changes was carried out in 19 healthy adult patients undergoing laparoscopic cholecystectomy. Following induction of anaesthesia, and throughout surgery, the end-tidal carbon dioxide tension was continuously monitored by capnography. The value following carbon dioxide insufflation increased with time to reach a maximum value after 40 min. Correlation of the individual maximum end-tidal carbon dioxide tension during laparoscopy with the corresponding baseline value prior to carbon dioxide insufflation showed a positive linear relationship (correlation coefficient 0.86). The correlation showed that an end-tidal carbon dioxide tension of 5.32 kPa (40 mmHg) can be achieved during laparoscopy when the baseline value is adjusted to around 4.0 kPa (30 mmHg).
• Laparoscopic cholecystectomy uses carbon dioxide, a highly diffusable gas, for insufflation. With extended periods of insufflation, patient arterial carbon dioxide levels may be adversely altered. Patients were selected for laparoscopic cholecystectomy using the same criteria as for open cholecystectomy. Twenty patients (group 1) had normal preoperative cardiopulmonary status (American Society of Anesthesiologists class I), while 10 patients (group 2) had previously diagnosed cardiac or pulmonary disease (class II or III). Demographic, hemodynamic, arterial blood gas, and ventilatory data were collected before peritoneal insufflation and at intervals during surgery. Patients with preoperative cardiopulmonary disease demonstrated significant increases in arterial carbon dioxide levels and decreases in pH during carbon dioxide insufflation compared with patients without underlying disease. Results of concurrent noninvasive methods of assessing changes in partial arterial pressures of carbon dioxide (end-tidal carbon dioxide measured with mass spectrographic techniques) may be misleading and misinterpreted because changes in partial arterial pressures of carbon dioxide are typically much smaller than changes in arterial blood levels and, unlike arterial gas measurements, do not indicate the true level of arterial hypercarbia. During laparoscopic cholecystectomy, patients with chronic cardiopulmonary disease may require careful intraoperative arterial blood gas monitoring of absorbed carbon dioxide.
(Arch Surg. 1991;126:997-1001)
14.45–15.00
O-150. Metabolic effect of the addition of 6% of O2 to the CO2
pneumoperitoneum
Mynbaev O.A.1,4, Molinas R.1, Vanacker B.3, Adamyan L.V.4 and
Koninckx P.C.1,2
1Centre for Surgical Technologies, Catholic University of Leuven,
Minderbroederstraat, 17 Leuven, 2Department of Obstetrics and
Gynaecology, 3Department of Anaesthesiology, University Hospital
Gasthuisberg, Catholic University of Leuven, Leuven Belgium and
4Department of Operative Gynaecology, Scientific Centre for Obstetrics,
Gynaecology and Perinatology, Russian Academy of Medical Sciences,
Moscow, Russia
Introduction: CO2-pneumoperitoneum during laparoscopic surgery is
associated with respiratory and cardiovascular changes and postoperative
complications such as postoperative pain, adhesion formation and risk of
thromboembolism. The addition of small amounts of oxygen to CO2 can
reduce the adhesiogenic effect. The aim of this study was to investigate
the effect of the addition of 6% O2 to CO2 upon CO2 absorption and
systemic effects.
Materials and methods: Three groups of adult female New Zealand
white rabbits (n � 10) were evaluated: a control group without pneumoperitoneum
(n � 3), 100% CO2 group (n � 4) and 6% O2 addition to
the CO2 group (n � 3). The animals were premedicated with an i.m.
injection of 30 mg/kg ketamine and 6 mg/kg of 2% xylazine hydrochloridum
solution. After intubation the anaesthesia was maintained with
2.5% halothane mixed with oxygen and room air (FiO2 � 70%). The
pneumoperitoneum was maintained with insufflation pressure of 10 mm
Hg (Thermoflotar Plus; Karl Storz). The gases were heated and humidified.
In all animals the ear artery was catheterized and arterial blood gases,
acid base and oxygen parameters were analysed before the start of
ventilation and subsequently after creation of the pneumoperitoneum
every 30 min for 210 min.
Results: Anaesthesia and ventilation only did not cause major changes
in the concentrations of blood gases, acid base and oxygen parameters.
The CO2 pneumoperitoneum was associated with a pronounced and
progressively increasing carboxaemia, as evidenced by the elevated pCO2
and tCO2. This CO2 accumulation caused acidaemia, which was initially
a respiratory acidosis and subsequently a metabolic acidosis as shown by
the progressively decreasing pH and increased concentrations of lactate
and HCO3
-. The carboxaemia also caused changes in the acid-base
balance as manifested by a progressively increasing base deficit and acid
excess. At the same time the sO2 and the concentration of O2Hb decreased,
and the p50 value and the concentration of RHb increased. At the end
of the experiment also the values of pO2 and tO2 decreased. The addition
of 6% O2 changed the effect of CO2 only. The carboxaemia and acidosis
were not only less pronounced, but also after 60 min a plateau wasobserved whereas with CO2 the effect increased progressively over 150–
180 min. Metabolic acidosis was much less pronounced, and the lactate
concentrations showed small increases only at the end of the experiment.
In contrast with the CO2 group, the p50 was less increased whereas the
values of tO2, sO2 and O2Hb, and of acid-base values remained within
background levels.
Conclusion: The CO2 pneumoperitoneum causes acidaemia, acidosis and
metabolic hypoxaemia. In this study the addition of 6% O2 to CO2 was
shown to prevent the metabolic changes and the tissue hypoxia in the
abdominal cavity. Therefore the addition of 6% O2 to CO2 could decrease
postoperative complications connected with CO2-pneumoperitoneum such
as adhesion formation and pain as well as the perioperative respiratory
and cardiovascular changes and postoperative risk of thromboembolism.
We studied 20 day case gynaecological laparoscopy patients, who had an erect chest X ray taken before discharge. Patients were telephoned the next day for a semi-structured interview. Particular note was made of shoulder tip pain and pain relieved by changing posture. The X ray was analysed for measurements of the length of arc and height of the gas bubble under each hemi-diaphragm, from which an estimation of bubble volume was also made. We found statistically significant correlations between both the length of arc (p = 0.005) and volume of gas bubble (p = 0.008) on the right side, with the pain score. Residual gas can be a prominent cause of post-laparoscopy pain.
Background:
Insufflation of CO2 into the abdomen is used during all kinds of laparoscopic operations. The procedure elicits haemodynamic and hormonal responses. The reports on sympathetic responses to laparoscopic surgery have been conflicting. However, few studies have assessed sympathetic and haemodynamic responses to CO2 insufflation per se, eliminating possible effects of intubation, skin incision, surgical manipulation and positioning of the body. No studies have measured both venous and arterial plasma catecholamines, the latter being a more sensitive indicator of sympathetic activity. In the present study, we hypothesised an increased sympathetic activity during pneumoperitoneum and an association between haemodynamic and sympathetic responses.
Methods:
Plasma adrenaline and noradrenaline from the radial artery and superior vena cava were measured immediately before and 10 min after abdominal insufflation of CO2 in 11 subjects. Haemodynamics were monitored invasively.
Results:
During pneumoperitoneum arterial plasma noradrenaline increased from 155 (106, 209) pg/ml (median, lowest and highest quartile) to 283 (188, 378) pg/ml (P = 0.003), while there were no changes in arterial plasma adrenaline. The calculated arterial-superior vena cava difference in plasma noradrenaline did not change, indicating no increased sympathetic activity in the drainage area of the superior vena cava. Heart rate and cardiac index were unchanged, while total peripheral resistance and mean arterial blood pressure increased (P = 0.002). The changes in arterial plasma noradrenaline were closely related to the changes in total peripheral resistance (r = 0.69, P = 0.01).
Conclusions:
Plasma noradrenaline increases during pneumoperitoneum and is associated with changes in total peripheral resistance. Plasma adrenaline is unchanged and there is no evidence of increased sympathetic outflow to the drainage area of the superior vena cava. Thus, the increase in plasma noradrenaline may be due to more local activation of the sympathetic nervous system, probably somewhere from the drainage area of the inferior vena cava.
The use of laparoscopy for the diagnosis or therapeutic management of abdominal disease in the horse has distinct advantages when it allows the horse to remain standing. However, distending the abdomen by insufflation of a biologically active gas in an anaesthetised horse may add to the physiological challenge of general anaesthesia and recumbency. The cardiopulmonary responses to abdominal insufflation with carbon dioxide (CO2) to 15 mmHg pressure were evaluated in 6 horses in dorsal recumbency anaesthetised with halothane in oxygen and subjected to laparoscopic colopexy. Vaporiser settings targeted a fractional expired halothane of 1.5 MAC and a clinically acceptable depth of anaesthesia. Pressure and rate controlled positive pressure ventilation was adjusted to an ETCO2 of 35 mmHg before abdominal insufflation and was not changed thereafter. Cardiopulmonary data were collected before, at 30 and 60 min during and 30 min after CO2 insufflation. ANOVA for repeated measures followed by Tukey's protected t test were used to determine differences. Partial pressure of oxygen and pH of arterial blood, tidal volume and systemic vascular resistance decreased during abdominal insufflation and laparoscopic surgery whereas mean arterial blood pressure, right atrial pressure, cardiac index, stroke index, partial pressure of CO2 in arterial blood and end tidal respiratory gases, and calculated physiological shunt increased significantly. Only systemic vascular resistance returned to the pre-insufflation level after desufflation. The hypercapnia, acidosis and apparent increase in cardiac work that accompany CO2 pneumoperitoneum for laparoscopic surgery could place the anaesthetised horse at additional risk of perioperative complications.
Acute increases in intraabdominal pressure (IAP) induce systemic and regional circulatory changes. Besides, mechanical compression on the capillary beds may decrease oxygen availability to the tissues. The purpose of this clinical study was to analyze the effects of increased IAP on acid-base disturbances and plasma lactate levels during prolonged carbon dioxide pneumoperitoneum.
Twenty-eight patients undergoing laparoscopic sigmoidectomy were included in this study. Fourteen of them (group A) had IAP of 15 +/- 1 mmHg while the remaining 14 (group B) had IAP of 10 +/- 1 mmHg. The control group included six patients undergoing conventional sigmoidectomy.
A progressive significant increase in PaCO2 was observed in the laparoscopic groups (p < 0.01). Plasma lactate levels in group A significantly increased 90 min after insufflation (p < 0.05) and reached the highest value 1 h after deflation (9.9 +/- 1 vs 31.9 +/- 2.5 mg/dl, p < 0.005). Simultaneously, arterial pH decreased in all groups; however, at 1 h after surgery, it was significantly lower (p = 0.02) in group A. There was a significant correlation between acid concentration due to lactate and lactate concentration (GA: R2 = 0.717, p = 0.03; GB: R2 = 0.879, p = 0.006 and GC: R2 = 0.853, p = 0.008).
High IAP causes lactic acidic accumulation in patients undergoing prolonged laparoscopic procedures.
This study analyzes the changes in cardiopulmonary parameters of patients undergoing laparoscopic cholecystectomy. Six healthy females with normal preoperative cardiopulmonary status were selected for laparoscopic surgery using the same criteria as for traditional cholecystectomy. Respiratory and cardiovascular parameters were collected and compared prior to peritoneal insufflation and just before desufflation. Patients experienced significant elevations of arterial and end-tidal CO2, accompanied by decreased pH. Bicarbonate concentration, blood pressure and pulse rate remained constant. Based on these results, and on our laboratory investigations, we have introduced helium as an alternate agent for insufflation, and present the data from the first two patients so managed. No change was observed in EtCO2, PaCO2 or pH in either of these two patients during the course of surgery. We conclude that hypercarbia occurs in those undergoing laparoscopic cholecystectomy with CO2 insufflation. This acidosis requires compensation by increased minute ventilation to prevent decline in pH. In our initial experience, helium did not produce these changes, and therefore merits further investigation as an alternate agent for abdominal insufflation.
We examined the changes in systemic blood volume and regional venous outflow from the splanchnic, coronary, and other remaining vascular beds in response to acute hypercapnia or hypoxic hypercapnia in dogs, using cardiopulmonary bypass and a reservoir. Hypercapnia (PCO2 = 105 mmHg) (1 mmHg = 133 Pa) and hypoxic hypercapnia (PO2 = 23 mmHg, PCO2 = 99 mmHg) caused marked decreases in systemic blood volume of 14 +/- 3 and 16 +/- 3 mL/kg in spleen-intact dogs, and 3 +/- 2 and 10 +/- 2 mL/kg in splenectomized dogs, respectively. Splanchnic venous outflow increased by 12% at 3.5 min hypercapnia, whereas it decreased by 60% at 3.5 min hypoxic hypercapnia. Coronary venous outflow increased by 85 and 400% at 3.5 min hypercapnia and hypoxic hypercapnia, respectively. Sympathetic efferent nerve activity revealed a significant augmentation during hypoxic hypercapnia and a relatively smaller increase (30% of the response to hypoxic hypercapnia) during hypercapnia. Carotid and aortic chemoreceptor and baroreceptor denervation attenuated significantly the response of systemic blood volume to hypercapnia and hypoxic hypercapnia. The regional venous outflow responses to hypercapnia were not altered after chemodenervation, but those to hypoxic hypercapnia were significantly attenuated after chemodenervation. These results suggest that acute hypercapnia and hypoxic hypercapnia caused a marked decrease in vascular capacitance owing primarily to an increase in sympathetic efferent nerve activity via chemoreceptor stimulation. They also indicate that blood flow to the splanchnic vascular bed during hypercapnia increased (even though the cardiac output was constant), whereas it increased to the extrasplanchnic and coronary vascular beds during hypoxic hypercapnia.
An investigation of end-tidal carbon dioxide tension changes was carried out in 19 healthy adult patients undergoing laparoscopic cholecystectomy. Following induction of anaesthesia, and throughout surgery, the end-tidal carbon dioxide tension was continuously monitored by capnography. The value following carbon dioxide insufflation increased with time to reach a maximum value after 40 min. Correlation of the individual maximum end-tidal carbon dioxide tension during laparoscopy with the corresponding baseline value prior to carbon dioxide insufflation showed a positive linear relationship (correlation coefficient 0.86). The correlation showed that an end-tidal carbon dioxide tension of 5.32 kPa (40 mmHg) can be achieved during laparoscopy when the baseline value is adjusted to around 4.0 kPa (30 mmHg).
The purpose of this experimental study was to determine the hemodynamic conditions of intraperitoneal viscera during pneumoperitoneum by using either CO2 gas or helium (He) for insufflation.
In 16 mongrel dogs (divided into a CO2 group and an He group) subjected to 14 mmHg pneumoperitoneum for 60 min, the following parameters were assessed at times before and 1, 2, 5, 15, 30, 45, and 60 min thereafter: (1) intestinal mucosal blood flow, by means of a laser-Doppler probe inplanted into a jejunal loop; (2) portal pressure and portal blood pCO2, through a catheter inserted via a mesenteric jejunal vein; (3) intramural jejunal pH (pHi), by means of a Tonometer, which expresses the degree of tissue ischemia; (4) inferior vena cava pressure and blood pCO2, through a catheter inserted via a femoral vein; and (5) from the systemic circulation pulse rate, arterial blood pressure, CO, CVP, PVP, SaO2, pCO2, and paO2 were measured through a catheter placed into a femoral artery and a Swan-Ganz thermodilution catheter inserted via the external jugular vein: CI and SVR were then calculated.
Jejunal mucosal blood flow was found decreased (P<0.0001) and pHi revealed gut mucosal ischemia. Portal and inferior vena cava pressures were found to be elevated (P<0.0001), as was blood pCO2 of these vessels (P<0.001), in only the CO2 group. From the systemic circulation, arterial blood pressure, CO, CI, SaO2, and paO2 revealed a decrease (P<0.001) while arterial pCO2 (only CO2 group), CVP, SVR, and PVP revealed an increase (P<0.001).
We conclude that severe hemodynamic alterations, not only to the systemic circulation but mainly to the viscera of the peritoneal cavity, are prominent after pneumoperitoneum for laparoscopic surgery. Elevation of portal and inferior vena cava pressures leads to splanchnic blood flow congestion and ischemia, while the use of CO2 seems to directly influence the pCO2.
Carbon dioxide absorption into the blood during laparoscopic surgery using intraperitoneal carbon dioxide insufflation may lead to respiratory acidosis, increased ventilation requirements, and possible serious cardiovascular compromise. The relationship between increased carbon dioxide excretion (VCO2) and intraperitoneal carbon dioxide insufflation pressure has not been well defined.
In 12 anesthesized pigs instrumented for laparoscopic surgery, intraperitoneal carbon dioxide (n = 6) or helium (n = 6) insufflation pressure was increased in steps, and VCO2 (metabolic cart), dead space, and hemodynamics were measured during constant minute ventilation.
VCO2 increases rapidly as intraperitoneal insufflation pressure increases from 0 to 10 mmHg; but from 10 to 25 mmHg, VCO2 does not increase much further. PaCO2 increases continuously as intraperitoneal insufflation pressure increases from 0 to 25 mmHg. Hemodynamic parameters remained stable.
By considering Fick's law of diffusion, the initial increase in VCO2 is likely accounted for by increasing peritoneal surface area exposed during insufflation. The continued increase in PaCO2 without a corresponding increase in VCO2 is accounted for by increasing respiratory dead space.
The effects of pneumoperitoneum with carbon dioxide and helium on systemic hemodynamics and arterial blood gases were investigated in pigs in an attempt to clarify the mechanisms by which pneumoperitoneum may induce organ dysfunction. A total of 16 anesthetized female pigs underwent pneumoperitoneum with carbon dioxide or helium (n = 8 each) in a stepwise fashion to intraabdominal pressures of 8, 10, 12, 16, and 20 mmHg. Changes in cardiac output; renal and hepatic blood flow; mean arterial, mean pulmonary arterial, mean pulmonary arterial wedge, inferior vena caval, and portal venous pressures; and total peripheral resistance were measured. Arterial blood samples were obtained at the same time the above parameters were determined. Urine volume was measured as an indicator of renal function. Pneumoperitoneum with either carbon dioxide or helium significantly increased venous pressures and simultaneously decreased cardiac output. These changes were associated with decreases in organ blood flow due to increased peripheral resistance. Urinary output was reduced to a similar degree in the two groups. Blood gas analysis revealed pneumoperitoneum-induced metabolic acidosis in both groups, although hypercapnia was observed only in the carbon dioxide group. These findings suggest that pneumoperitoneum-related organ dysfunction may be due to increased intraperitoneal pressure rather than to hypercapnia.
We studied 20 day case gynaecological laparoscopy patients, who had an erect chest X ray taken before discharge. Patients were telephoned the next day for a semi-structured interview. Particular note was made of shoulder tip pain and pain relieved by changing posture. The X ray was analysed for measurements of the length of arc and height of the gas bubble under each hemi-diaphragm, from which an estimation of bubble volume was also made. We found statistically significant correlations between both the length of arc (p = 0.005) and volume of gas bubble (p = 0.008) on the right side, with the pain score. Residual gas can be a prominent cause of post-laparoscopy pain.
Alternative methods of exposure are needed for minimally invasive surgery to avoid hypercarbia and acidosis associated with carbon dioxide (CO2) abdominal insufflation. The goals of this study were to determine the pulmonary and hemodynamic effects of both helium (HE) abdominal insufflation and placement of a mechanical abdominal wall-lifting device (lifter) during laparoscopy.
Sixteen adult domestic pigs under general endotracheal anesthesia underwent baseline measurements of pulmonary capillary wedge pressure (PCWP), cardiac output (CO), and arterial blood gas. Six pigs underwent standard CO2 abdominal insufflation, five pigs underwent abdominal insufflation with HE, and a lifter was used for exposure in five other animals. Sequential readings of PCWP, CO, and arterial blood gas were recorded at 20-min intervals for 60 min in all 16 animals.
No significant changes from baseline values were noted in arterial pCO2 or pH in animals who underwent placement of the lifter at any time point. After undergoing HE insufflation, animals experienced modest but significant acidosis and little change in pCO2. There was a significant rise in arterial pCO2 and decrease in pH from baseline values at all time points in animals undergoing CO2 insufflation.
This study shows that neither HE abdominal insufflation or the lifter have significant deleterious pulmonary or hemodynamic effects on experimental animals during laparoscopy. Gasless laparoscopy or HE insufflation may provide a safer alternative method of exposure for minimally invasive surgery in patients with pre-existing pulmonary or cardiac dysfunction. By minimizing risk in these patients, costly invasive monitoring may be avoided.
Laparoscopic liver biopsy can be safely performed using local anesthesia and intravenous sedation, but the frequency of hypoxemia is unknown.
We prospectively studied 68 patients undergoing diagnostic laparoscopy and liver biopsy managed by a standard protocol.
The mean duration of laparoscopy was 27 +/- 5.53 minutes; the mean dose of diamorphine administered was 6.9 +/- 2.7 mg; diazepam, 7.05 +/- 3.52 mg. The baseline arterial oxygen saturation was 95.6% +/- 2.5% and trough was 85% +/- 5.1%. A fall of greater than 4% saturation from the baseline occurred in 64 out of 68 patients (94%). The mean decrease in saturation was 10.1% +/- 5.4%. An arterial oxygen saturation of less than 85% was seen in 32 patients (47%). There was no correlation between the fall in oxygen saturation and the dose of diamorphine or diazepam, the duration of procedure, body mass index, hemoglobin, or volume of pneumoperitoneum induced. One-way analysis of the variance failed to show a significant relationship between the degree of oxygen saturation and Child's class, etiology of liver disease, or smoking habit.
In this study, we demonstrated that significant desaturation is common in diagnostic laparoscopy with liver biopsy and is likely due to a combination of different pharmacologic and physiologic effects. We recommend continuous monitoring of both arterial oxygen saturation and supplemental oxygen for all patients throughout laparoscopy.
Abdominal CO2 insufflation has been shown to cause hypercarbia, acidemia, and decreased oxygenation in a pediatric animal model. Such metabolic derangements have prompted a search for alternative insufflation gases. This study compares the hemodynamic and ventilatory changes that occur during pneumoperitoneum with CO2 and helium. Four juvenile swine were intubated and given general anesthesia. Minute ventilation was adjusted to obtain a baseline Pco2 of between 32 and 36 mm Hg, and was kept constant for the duration of the experiment. The subjects initially were insufflated with CO2 or helium at a pressure of 10 mm Hg. Peak ventilatory pressure, end-tidal CO2 (ETCO2) arterial pH, Pco2, Po2, and right atrial and inferior vena caval pressures were measured before and during a 1-hour insufflation period. After desufflation, Pco2 and pH were restabilized. The same parameters were then measured during reinsufflation with the alternate gas. CO2 insufflation caused significant decreases in pH, from 7.51 +/- 0.03 to 7.32 +/- 0.06, and Po2 increased from 261 +/- 49 to 189 +/- 33 mm Hg. Pco2 increased from 35.0 +/- 1.4 to 57.9 +/- 6.3 mm Hg. ETCO2 also increased, from 29.0 +/- 2.2 to 47.2 +/- 5.0 mm Hg. Helium insufflation caused pH to decrease from 7.51 +/- 0.01 to 7.42 +/- 0.04. Pco2 increased from 32.8 +/- 0.8 to 43.5 +/- 3.9 mm Hg, and ETCO2 increased from 27.8 +/- 0.5 to 36.8 +/- 3.1 mm Hg. These alterations were significantly less than those with CO2 pneumoperitoneum. Po2 decreased as well-from 266 +/- 30 to 212 +/- 21 mm Hg. During insufflation with both gases, peak ventilatory pressure and right atrial pressure increased significantly. Abdominal insufflation with CO2 or helium causes hypercarbia, acidemia, and increased ETCO2 in this juvenile animal model. These derangements are significantly less with helium. This gas may prove to be the more suitable insufflation agent for pediatric patients.
This study compares the cardio-respiratory effects of CO2 pneumoperitoneum to those of abdominal suspension (or laparolift) in laparoscopic cholecystectomy. Between september 1993 et may 1995, 31 patients participated in this non-randomized prospective trial. They consisted of 9 males et 22 females, with a mean age of 47.0 +/- 14 years. Sixteen patients were included in the CO2 group and 15 in the laparolift group. Both groups were comparable for age and gender. All patients were submitted to the same anaesthetic protocol. Repeated measurements of the respiratory and cardiovascular function were made during the intervention. End tidal CO2, minute ventilation, peak inspiratory pressure showed superior elevations in the CO2 group. And for the hemodynamic parameters, only the mean arterial pressure and cardiac frequency differed between the two groups, other hemodynamic parameters including left ventricular ejection fraction were comparable. Also, postoperatory hospital stay, OR time, per and postoperatory complications were comparable. With its stable hemodynamic and ventilatory pattern, abdominal suspension can constitute a safe and secure alternative to CO2 pneumoperitoneum in patients with respiratory dysfunction.
The purpose of this study was to investigate the effects of increasing intraabdominal pressure (IP) on gastric blood flow, as measured by gastric tonometry and traditional hemodynamic measurements.
Nine swine were anesthetized, intubated, and ventilated. Arterial and pulmonary artery catheters were placed by cutdown, a trocar was placed in the abdomen, and a gastric tonometer was placed in the stomach. Serial measurements of arterial and mixed venous blood gases, cardiac output, wedge pressure, lactic acid, and gastric intramucosal pH (pHi) were collected at intraperitoneal pressures of 0, 8, 10, 12, 14, 16, and 18 mm Hg after 30 min equilibration. Statistical analysis included Pearson correlation and Student's t test.
Increasing levels of IP were correlated with decreased arterial pH (p < 0.00003), increased mixed venous CO2 (p < 0.003), decreased intramucosal pH (p < 0.014), and increased arterial CO2 (p < 0.015). Gastric pHi differed significantly from baseline at IP levels of 16 mm Hg (p < 0.004) and 18 mm Hg (p < 0.01). No significant effects were observed on cardiac output or arterial lactate. No significant effects were observed in a control group that had been insufflated to 8 mm Hg and held constant over 3 h.
In this model, gastric blood flow is adversely affected by increasing i.p. with pronounced effects in excess of 15 mm Hg. These results suggest that gastric tonometry may be used to monitor the adverse effects of pneumoperitoneum. Gastric pHi may be an earlier indicator of altered hemodynamic function during laparoscopy than traditional measures.
Diagnostic laparoscopy has been used in abdominal trauma patients, although its role is not well defined. The safety of laparoscopic evaluation in trauma patients with severe intraabdominal hemorrhage has not yet been analyzed. The purpose of this study is to evaluate the hemodynamic and metabolic effects of CO2 pneumoperitoneum (COI) in hemorrhaged animals through a retroperitoneal hematoma (RH).
Twenty-two 15-20-kg mongrel dogs were monitored for systemic and pulmonary hemodynamics, inferior vena cava pressure, and arterial blood gases. After 1 h of baseline, all animals were submitted to a RH. After 45 min the dogs were randomized into two groups. Control (CTR): dogs were submitted only to a RH; pneumoperitoneum (PN): dogs were submitted to a RH and 45 min later they were insufflated to an intraabdominal pressure of 10 mmHg with medical-grade CO2 gas for 30 min. Echocardiography was performed, only in PN animals, at baseline, 45 and 60 min after RH.
RH induced a shock condition with low, sustained levels of arterial pressure, cardiac index, left ventricular stroke index, base excess, and oxygen delivery which were further depressed following COI. Three deaths occurred in the PN group, all of them toward the end of COI. During COI, hypercapnia was observed in one animal. COI did not impair systolic function or ejection fraction.
COI with an IAP of 10 mmHg may be deleterious in animals with hemorrhagic shock due to an intraabdominal lesion. These findings could be clinically significant in abdominal trauma patients.
To compare tumor growth, intraperitoneal implantation, and abdominal wall metastasis after laparotomy and CO2 pneumoperitoneum in a rat ovarian cancer model.
To mimic intraoperative rupture of an ovarian tumor in a syngenic rat ovarian carcinoma model, 10(5) malignant cells were injected intraperitoneally after a 5-cm vertical midline laparotomy or after the insufflation of a CO2 pneumoperitoneum achieved with 4 mmHg or 10 mmHg intra-abdominal pressure. Two weeks later, the intraperitoneal tumor growth and the tumor dissemination were evaluated semiquantitatively with a scoring system. The scores attributed to each organ were added to calculate the dissemination score of each animal.
The mean (+/-SD) dissemination score was 83.4+/-12 in the laparotomy group and 67.3+/-16 and 71.9+/-17 in the 4 and 10 mmHg CO2 pneumoperitoneum groups, respectively (P < .01). The scores for the peritoneum were 21.8+/-3.8 in the 10 mmHg pneumoperitoneum group and 18+/-2.4 in the laparotomy group (P < .01). In the laparotomy group, the implant found along the midline scar accounted for a mean of 62.6+/-15% of the peritoneal score, whereas the trocar site metastases did not influence the peritoneal score in the pneumoperitoneum groups. The incidence of wound metastasis was 96% in the laparotomy group and 55% and 54% in the 4 mmHg and 10 mmHg pneumoperitoneum groups, respectively.
In this model, tumor growth was greater after laparotomy than after laparoscopy, but peritoneal tumor dissemination was more severe after CO2 pneumoperitoneum.
We investigated endocrine correlates of the hemodynamic changes induced by carbon dioxide pneumoperitoneum (PNO). We then studied whether clonidine might modulate the hemodynamic changes induced by PNO by reducing release of catecholamines and vasopressin.
Both mechanical and neurohumoral factors contribute to the hemodynamic changes induced by carbon dioxide PNO. Several mediators have been proposed, but no study has correlated hemodynamic changes with changes in levels of these potential mediators.
We conducted two studies, each including 20 healthy patients scheduled for elective laparoscopic cholecystectomy. In the first study serial measurements of hemodynamics (thermodilution technique) were done during laparoscopy and after exsufflation. Plasma concentrations of cortisol, catecholamines, vasopressin, renin, endothelin and prostaglandins were measured at the same time points. In the second study patients were randomly allocated to receive 8 microg/kg clonidine infused over 1 h or placebo before PNO. Hemodynamics and plasma levels of cortisol, catecholamines and vasopressin were measured during PNO and after exsufflation.
Peritoneal insufflation resulted in a significant reduction of cardiac output (18+/-4%) and increases in mean arterial pressure (39+/-8%) and systemic (70+/-12%) and pulmonary (98+/-18%) vascular resistances. Laparoscopy resulted in progressive and significant increases in plasma concentrations of cortisol, epinephrine, norepinephrine and renin. Vasopressin plasma concentrations markedly increased immediately after the beginning of PNO (before PNO 6+/-4 pg/ml; during PNO 129+/-42 pg/ml; p < 0.05). The profile of vasopressin release paralleled the time course of changes in systemic vascular resistance. Prostaglandins and endothelin did not change significantly. Clonidine significantly reduced mean arterial pressure, heart rate and the increase in systemic vascular resistance. Clonidine also significantly reduced catecholamine concentrations but did not alter vasopressin and cortisol plasma concentrations.
Vasopressin and catecholamines probably mediate the increase in systemic vascular resistance observed during PNO. Clonidine before PNO reduces catecholamine release and attenuates hemodynamic changes during laparoscopy.
The effect of the tumour-bearing state and alterations in peritoneal immune function on the incidence of port-site and peritoneal metastases was investigated after laparoscopy with and without CO2 pneumoperitoneum.
A suspension of viable adenocarcinoma cells was introduced into the left upper quadrant of the peritoneal cavity of syngeneic tumour-bearing rats at laparotomy, laparoscopy with CO2, and gasless laparoscopy. Control rats did not have pre-existing tumours. A group of non-tumour-bearing rats were also injected intraperitoneally with endotoxin 4 h before intraperitoneal tumour cell injection. Six days later the peritoneal cavity and surgical wounds were examined for macroscopic evidence of implanted tumour. Peritoneal macrophages were obtained from tumour-bearing rats subjected to different laparoscopic procedures and the activation state measured following exposure to lipopolysaccharide in vitro.
In the control rats, tumour implantation in the surgical wounds and peritoneum was significantly greater in the rats that had undergone laparoscopy with CO2. The presence of a pre-existing tumour was associated with increased tumour spread in all treatment groups and at most sites. Injection of endotoxin also resulted in increased tumour spread. Peritoneal macrophages from control and tumour-bearing rats who underwent laparoscopy with CO2 produced significantly less TNF-alpha in vitro, compared to gasless laparoscopy or laparotomy.
Carbon dioxide insufflation enhances tumour spread and implantation. The underlying immune or metabolic status of the host, as influenced by the tumour-bearing state or modification of the peritoneal environment, also has a marked independent effect on tumour spread and implantation. The immune and metabolic status of the peritoneum including the extent of macrophage activation is implicated in this effect.
The application of a CO2-pneumoperitoneum in operative laparoscopy presumably leads to basic alterations of the intraperitoneal homeostasis. In order to better understand the pathophysiology of this phenomenon, the morphologic alterations of the mesothelium after CO2-application will be examined.
In 36 mice (C 57, black mice) a CO2-pneumoperitoneum with an intraperitoneal pressure of 6 mm Hg was applied for 30 minutes. After 1, 2, 6, 12, 24, 48, 72 and 96 hours each of 4 animals were killed and the entire peritoneum was examined by scanning electron microscopy.
Already after 1 hour mesothelial cells became cuboidal, were detached and showed condensation. After 2 hours this initial reaction reached its peak; immature cells then attached to the free basal membrane. After 96 hours the entire mesothelium was regenerated.
The morphologic integrity of the mesothelium is temporarily disturbed by a CO2-pneumoperitoneum. Reasons for this phenomenon may be either the abdominal pressure or a CO2-induced surface acidosis. In further studies, the influence of the described phenomena on intraperitoneal formation of metastases will be examined.
Minimally invasive therapy aims to minimize the trauma of any interventional process but still achieve a satisfactory therapeutic result. The development of "critical pathways," rapid mobilization and early feeding have contributed towards the goal of shorter hospital stay. This concept has been extended to include laparoscopic cholecystectomy and hernia repair. Reports have been published confirming the safety of same day discharge for the majority of patients. However, we would caution against overenthusiastic ambulatory laparoscopic cholecystectomy on the rational but unproven assumption that early discharge will lead to occasional delays in diagnosis and management of postoperative complications. Intraoperative complications of laparoscopic surgery are mostly due to traumatic injuries sustained during blind trocar insertion and physiologic changes associated with patient positioning and pneumoperitoneum creation. General anesthesia and controlled ventilation comprise the accepted anesthetic technique to reduce the increase in PaCO2. Investigators have recently documented the cardiorespiratory compromise associated with upper abdominal laparoscopic surgery, and particular emphasis is placed on careful perioperative monitoring of ASA III-IV patients during insufflation. Setting limits on the inflationary pressure is advised in these patients. Anesthesiologists must maintain a high index of suspicion for complications such as gas embolism, extraperitoneal insufflation and surgical emphysema, pneumothorax and pneumomediastinum. Postoperative nausea and vomiting are among the most common and distressing symptoms after laparoscopic surgery. A highly potent and selective 5-HT3 receptor antagonist, ondansetron, has proven to be an effective oral and IV prophylaxis against postoperative emesis in preliminary studies. Opioids remain an important component of the anesthesia technique, although the introduction of newer potent NSAIDs may diminish their use. A preoperative multimodal analgesic regimen involving skin infiltration with local anesthesia. NSAIDs to attenuate peripheral pain and opioids for central pain may reduce postoperative discomfort and expedite patient recovery/discharge. There is no conclusive evidence to demonstrate clinically significant effects of nitrous oxide on surgical conditions during laparoscopic cholecystectomy or on the incidence of postoperative emesis. Laparoscopic cholecystectomy has proven to be a major advance in the treatment of patients with symptomatic gallbladder disease.
According to the literature, the number of port-site metastases in laparoscopic surgery varies considerably depending on the type of gas used for the pneumoperitoneum. In order to investigate this observation we studied the changes in blood, subcutaneous, and intra-abdominal pH during laparoscopy with helium, CO(2) and room air in a rat model. In addition, we looked at the influence of intra-abdominal pressure and duration of pneumoperitoneum on the pH during the laparoscopy.
pH was measured by tonometry, intra-abdominally and subcutaneously. A pH electrode was additionally placed into the subcutaneous tissue and the results compared to those measured by tonometry. Blood samples were taken from a catheter in the carotid artery. The intra-abdominal pressure was 0, 3, 6, 9 mm Hg for 30 min in each case. We investigated the effect of pneumoperitoneum with CO(2), helium and air in randomized groups of 5 rats. In an additional series the pressure was held constant at 3 mm Hg and the pH was measured every 30 min.
Due to the different absorption capacity of the peritoneum, laparoscopy with CO(2) decreases the subcutaneous pH from 7.35 to 6.81. Blood pH is reduced from 7.37 to 7.17 and the intra-abdominal pH from 7.35 to 6.24. Other, less absorbable gases induce smaller changes of blood and subcutaneous pH (only 10% of CO(2)). In a variance analysis the p value is less than 0.001. The influence of duration of laparoscopy (30 min vs. 90 min) on the subcutaneous pH is less compared to the influence of intra-abdominal pressure (0, 3, 6, 9 mm Hg).
Depending on the type of gas (CO(2), air, helium) used for laparoscopy blood, subcutaneous and intra-abdominal pH are influenced differently. Because lower pH is known to impair local defense mechanisms, these results may be one explanation for the higher incidence of port-site metastasis in laparoscopy with CO(2) than with other gases, as reported in the literature.
30-67% of patients undergoing laparoscopic surgery reports shoulder pain. Besides, post-surgical course of patients undergoing converted laparoscopic procedures is similar to the course of patients who received a completely laparoscopic procedure. It is supposed that there is a temporary neurotoxic damage of the peritoneal sensitive nervous fibres defined by CO2.
A prospective review has been carried out by histologically analyzing 38 peritoneal biopsies from 10 selected patients, during different laparoscopic surgical procedures (6 cholecystectomies, 2 appendectomies, 1 selective bilateral ligature of the spermatic vessles) and at different times during each operation. Patients whom anamnesis, clinical or local conditions were suggestive for peritoneal flogosis were excluded from the study: therefore only 29 biopsies from 8 patients have been considered useful to the study.
Histological analysis has been carried out with different methods of coloration (hematoxylin eosin, argentic staining) and at different magnifications (30x, 60x, 100x), without electronical microscopy or immunohistochemical studies. No biopsy showed signs of damage of the nervous structures.
Certainly, the realization of a pneumoperitoneum at CO2 doesn't cause damages of the peritoneal sensitive fibres. It has been demonstrated that the abdominal introduction of CO2 causes a "relative peritoneal acidosis", directly depending from the percentage of CO2 employed: the peritoneal pH decreases to 6.9 after 15 min of pneumoperitoneum with CO2 at 100% and to 7.35% with CO2 at 5% of air. Probably this condition causes a temporary biochemical change that defines reduction of the nervous impulses and, therefore, the "peritoneization" of the patient subjected to laparoscopic procedure. The "biochemical hypoesthesia", based on a change of the peritoneal homeostasis, would translate itself in a beneficial effect for the patient, persisting also when converted to laparotomic operation due the impossibility to proceed under laparoscopy, held up by the residual pneumoperitoneum.
Experimental studies and clinical experience suggest that the combination of positive end-expiratory pressure (PEEP) ventilation and intra-abdominal hypertension might alter splanchnic hemodynamics to a significantly greater degree than the effect of either of them alone. Therefore, we assessed the intestinal and hepatic hemodynamics in two steps of PEEP ventilation, adding tense pneumoperitoneum in a pig model. The hepatic artery, portal vein, and superior mesenteric artery blood flow, as well as the hepatic and intestinal mucosal microcirculation, and the hepatic pO2 and intestinal mucosal pH, were assessed before, then with 5 cmH2O and 10 cmH2O PEEP alone, and in combination with a 12-mmHg pneumoperitoneum, in ten domestic pigs. Statistical analysis of the hepatic and intestinal measurements revealed a significant decrease (P = 0.001) in all parameters in relation to the baseline, during the 5-cmH2O and 10-mmH2O PEEP ventilation period. The addition of 12 mmHg intra-abdominal pressure led to an extreme deterioration in all parameters (P = 0.001), in relation to both the baseline and the 10-cmH2O PEEP measurement. These findings demonstrate that PEEP and intra-abdominal hypertension act cumulatively on the abdominal viscera, producing conditions of extremely low hypoperfusion and ischemia.
Volume-dependent alterations of lung compliance are usually studied over a very large volume range. However, the course of compliance within the comparably small tidal volume (intratidal compliance-volume curve) may also provide relevant information about the impact of mechanical ventilation on pulmonary gas exchange. Consequently, we determined the association of the distribution of ventilation and perfusion with the intratidal compliance-volume curve after modification of positive end-expiratory pressure (PEEP).
Repeated measurements in randomized order.
An animal laboratory.
Isolated perfused rabbit lungs (n = 14).
Surfactant was removed by bronchoalveolar lavage. The lungs were ventilated thereafter with a constant tidal volume (10 mL/kg body weight). Five levels of PEEP (0-4 cm H2O) were applied in random order for 20 mins each.
The intratidal compliance-volume curve was determined with the slice method for each PEEP level. Concurrently, pulmonary gas exchange was assessed by the multiple inert gas elimination technique. At a PEEP of 0-1 cm H2O, the intratidal compliance-volume curve was formed a bow with downward concavity. At a PEEP of 2 cm H2O, concavity was minimal or compliance was almost constant, whereas higher PEEP levels (3-4 cm H2O) resulted in a decrease of compliance within tidal inflation. Pulmonary gas exchange did not differ between PEEP levels of of 0, 1, and 2 cm H2O. Pulmonary shunt was lowest and perfusion of alveoli with a normal ventilation-perfusion was highest at a PEEP of 3-4 cm H2O. Deadspace ventilation did not change significantly but tended to increase with PEEP.
An increase of compliance at the very beginning of tidal inflation was associated with impaired pulmonary gas exchange, indicating insufficient alveolar recruitment by the PEEP level. Consequently, the lowest PEEP level preventing alveolar atelectasis could be detected by analyzing the course of compliance within tidal volume without the need for total lung inflation.
To develop a laparoscopic mouse model to evaluate the hypothesis that mesothelial hypoxia during pneumoperitoneum is a cofactor in adhesion formation.
Prospective randomized trials.
Academic research center.
One hundred thirty female Naval Medical Research Institute (NMRI) mice.
Adhesions were induced by opposing monopolar lesions in uterine horns and pelvic side walls during laparoscopy and evaluated after 7 or 28 days under microscopic vision during laparotomy. The following pneumoperitoneum variables were assessed: duration (10 or 60 minutes), insufflation pressure (5 or 15 cm of water), insufflation gas (CO(2) or helium), and addition of oxygen (0-12%).
Adhesions were scored quantitatively and qualitatively for extent, type, and tenacity.
Scoring of adhesions 7 or 28 days after laparoscopic surgery was comparable. Adhesions increased with duration of pneumoperitoneum and with insufflation pressure and decreased with the addition of oxygen. Half-maximal reduction of adhesions was obtained at 1.5% oxygen, whereas a maximal reduction required only 2%-3%. The effect of CO(2) and helium was similar.
These data demonstrate the feasibility of the intubated laparoscopic mouse model and confirm previous observations in rabbits, indicating that mesothelial hypoxia plays a key role in adhesion formation.
Laparoscopy and adhesions: What role for hypoxemia? Presented at the expert conference of the European Society for Gynaecological Endoscopy
- P R Koninckx
Koninckx PR: Laparoscopy and adhesions: What role
for hypoxemia? Presented at the expert conference of
the European Society for Gynaecological Endoscopy,
Clermont-Ferrand, France, October 18, 2000
Loss of cell viability due to CO2 pneumoperitoneum during laparoscopy and maintenance of cell viability at laparoscopy by hydration of CO2 [abstr]
- Garner