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ORIGINAL ARTICLE
Lung recruitment prevents collapse during laparoscopy
in children
A randomised controlled trial
Cecilia M. Acosta, Toma
´s Sara, Martı
´n Carpinella, Giovanni Volpicelli, Lila Ricci, Sergio Poliotto,
Diego Abrego, Sergio Gonorazky, Stephan H. Bo
¨hm and Gerardo Tusman
BACKGROUND Capnoperitoneum and anaesthesia impair
lung aeration during laparoscopy in children. These changes
can be detected and monitored at the bedside by lung
ultrasound (LUS).
OBJECTIVE The aim of our study was to assess the impact
of general anaesthesia and capnoperitoneum on lung col-
lapse and the potential preventive effect of lung recruitment
manoeuvres, using LUS in children undergoing laparoscopy.
DESIGN Randomised controlled study.
SETTING Single-institution study, community hospital, Mar
del Plata, Argentina.
PATIENTS Forty-two children American Society of Anesthe-
siologists I–II aged 6 months to 7 years undergoing laparos-
copy.
INTERVENTIONS All patients were studied using LUS
before, during and after capnoperitoneum. Children were
allocated to a control group (C-group, n¼21) receiving
standard protective ventilation, or to a lung recruitment
manoeuvre group (RM-group) (n¼21), in which lung recruit-
ment manoeuvres were performed after recording baseline
LUS images before capnoperitoneum. Loss of aeration was
scored by summing a progressive grading from 0 to 3
assigned to each of 12 lung areas, based on the detection
of four main ultrasound patterns: normal aeration ¼0,
partial loss-mild ¼1, partial loss-severe ¼2, total loss-
consolidation ¼3.
MAIN OUTCOME MEASURES Lung aeration score and
atelectasis assessed by ultrasound.
RESULTS Before capnoperitoneum and recruitment man-
oeuvres in the treated group the two groups presented
similar ultrasound scores (5.95 "4.13 vs. 5.19 "3.33,
P¼0.5). In the RM-group, lung aeration significantly
improved both during (2.71 "2.47) and after capnoperito-
neum (2.52 "2.86), compared with the C-group
(6.71 "3.54, P<0.001, and 8.48 "3.22, P<0.001,
respectively). There was no statistically significant difference
in the percentage of atelectasis before capnoperitoneum and
recruitment manoeuvres in the RM-group (62%) and in the
C-group (47%, P¼0.750). However, during capnoperito-
neum, only 19% of the RM-group had atelectasis compared
with 80% in the C-group (P<0.001).
CONCLUSION The majority of children undergoing laparos-
copy have anaesthesia-induced atelectasis. In most cases,
lung collapse due to capnoperitoneum could have been
prevented by recruitment manoeuvres followed by posi-
tive-end expiratory pressure.
TRIAL REGISTRY NUMBER NCT02824146.
Published online 22 December 2017
Introduction
In anaesthetised children, the incidence of lung collapse
with episodes of hypoxaemia is high.
1–5
Diaphragm
dysfunction induced by general anaesthesia is one of
the most important factors in the genesis of regional
losses of lung aeration.
1,2
The mass of the abdominal
organs pushes the diaphragm cranially compressing the
Eur J Anaesthesiol 2018; 35:573– 580
From the Department of Anaesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina (CMA, TS, MC, GT), Department of Emergency Medicine, San Luigi
Gonzaga University Hospital, Torino, Italy (GV), Department of Mathematics, Facultad de Ciencias Exactas, Universidad Nacional de Mar del Plata (LR), Department of
Pediatric Surgery (SP, DA), Department of Clinical Research, Hospital Privado de Comunidad, Mar del Plata, Argentina (SG) and Hepa Wash GmbH, Munich, Germany
(SHB)
Correspondence to Gerardo Tusman, MD, Department of Anaesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina
Tel: +54 223 4990074; fax: +54 223 4990099; e-mail: gtusman@hotmail.com
0265-0215 Copyright !2018 European Society of Anaesthesiology. All rights reserved. DOI:10.1097/EJA.0000000000000761
Copyright © European Society of Anaesthesiology. Unauthorized reproduction of this article is prohibited.
lungs in the most dependent areas. Such regional lung
collapse may range from slight loss of aeration to com-
plete atelectasis.
6– 11
Capnoperitoneum induced during laparoscopy may
aggravate lung collapse as it generates a further increase
in intra-abdominal pressure.
12
Because the chest wall and
abdomen work in series, impairment of abdominal com-
pliance induced by capnoperitoneum may significantly
influence thoracic compliance, causing changes in the
pleural pressure.
13
Neonates, infants and small children
have in common low functional residual capacity, high
pulmonary closing capacity and high oxygen consump-
tion, and are especially prone to develop atelectasis and
hypoxaemia during laparoscopic procedures.
14,15
Lung recruitment manoeuvres have the potential to
improve lung aeration and gas exchange in adults and
children during nonlaparoscopic procedures.
8,11,16
Lapa-
roscopic studies have shown that recruitment man-
oeuvres successfully improved lung mechanics and
atelectasis in adults, but similar data have not been
obtained in children.
17– 19
Lung ultrasound (LUS) is a reliable and accurate nonin-
vasive imaging tool for detecting anaesthesia-induced
atelectasis.
10
LUS has great potential for bedside assess-
ment and monitoring of lung aeration particularly when
the effect of therapeutic intervention is assessed in
critically ill patients.
20,21
It is a tool that appears suitable
for use with children for observing changes in lung
aeration during laparoscopy with general anaesthesia.
The aim of our study was to assess the impact of general
anaesthesia and capnoperitoneum on lung collapse and
the beneficial effect of recruitment manoeuvres, using
LUS examinations of children undergoing laparoscopy.
Our main hypothesis was that the loss of lung aeration
during capnoperitoneum was higher in children venti-
lated with standard protective ventilation compared with
those receiving similar ventilation preceded by recruit-
ment manoeuvres.
Methods
Ethical approval for this study (no. 2919/875/14) was
provided by the Ethical Committee of Hospital Privado
de Comunidad – CIREI, Mar del Plata, Argentina on 7
July 2014. The study started at the end of August 2014.
The current randomised controlled clinical trial (trial
registration number NCT02824146) was performed in
the operating theatre of a community hospital. After
signed informed parental consent, we studied children
aged 6 months to 7 years with a physical status classifica-
tion [American Society of Anesthesiologists (ASA)] I – II,
undergoing abdominal laparoscopic surgery. We
excluded emergency and thoracic procedures, patients
with abdominal distension or with significant pre-existing
pulmonary, cardiac or chest wall diseases.
Anaesthesia
Standard ECG, noninvasive mean systemic arterial pres-
sure, time-based capnography and pulse oximetry were
monitored by the S/5 device (Datex-Ohmeda, Helsinki,
Finland). Anaesthesia was induced with Sevofluorane
using the circle system of the GE Aespire workstation
(GE Healthcare, Madison, Wisconsin, USA). Fentanyl
3mg kg
#1
and vecuronium 0.1 mg kg
#1
were adminis-
tered intravenously before intubation with a cuffed
endotracheal tube of appropriate size. Anaesthesia was
maintained with sevoflurane 0.7 minimum alveolar
concentration and a remifentanil infusion (0.5 to
0.6 mg kg
#1
min
#1
). All children were studied in the
supine position.
The lungs were ventilated in a volume control mode
using a tidal volume of 6 ml kg
#1
, a positive end-expira-
tory pressure (PEEP) of 5 cmH
2
O, an inspiratory: expira-
tory ratio of 1 : 1.5, respiratory rate between 20 and
25 breaths per minute and FIO
2
of 0.5. Respiratory
flow and pressure signals were obtained by a paediatric
D-Lite adapter (GE-Datex Side Stream System, GE
Healthcare, Madison, Wisconsin, USA) placed at the
airway opening (S/5, Datex-Ohmeda). Tidal volume,
PEEP and dynamic respiratory compliance [Cdyn (respi-
ratory system dynamic compliance) ¼tidal volume/peak
airway pressure #PEEP] were recorded on a chart at each
protocol step.
Lung ultrasound
LUS was performed with the portable device MicroMax
(Sonosite, Bothell, Washington, USA) using a linear
probe of 6 to 12 MHz. Each hemithorax was divided into
six regions, as previously described, using three longitu-
dinal lines (parasternal, anterior and posterior axillary)
and two axial lines (one above the diaphragm and the
other 1 cm above the nipples).
10,22
Each hemithorax was
assessed by placing the probe perpendicular to the ribs
looking for the bat sign (the pleura and lung tissue
between the acoustic shadows of two adjacent ribs).
10,23
Once a complete hemithorax scan was performed, the
probe was then placed in the oblique position between
ribs in those areas in which the typical ultrasound pat-
terns of atelectasis were detected. In general, the poste-
rior areas are those with the highest incidence of
anaesthesia-induced atelectasis.
7– 10
An aeration score
previously described for adults was applied in our paedi-
atric patients.
20
Four LUS patterns were defined and
assessed in each of the six thoracic areas per side:
Normal aeration (N): presence of lung sliding (the respira-
tory movement of the visceral pleura relative to the fixed
parietal pleura) and A lines (repetitive horizontal rever-
beration artefacts generated by air within the lungs
separated by regular intervals).
Moderate loss of lung aeration (B1): multiple and well
defined B-lines (vertical, dynamic and laser-like echoic
574 Acosta et al.
Eur J Anaesthesiol 2018; 35:573–580
Copyright © European Society of Anaesthesiology. Unauthorized reproduction of this article is prohibited.
lines, originating from the pleural line or from small
subpleural consolidations, reaching the lowest edge of
the screen).
Severe loss of lung aeration (B2): multiple coalescent B-
lines that occupy the whole lung image (the so-called
white lung).
Complete loss of aeration (C): Anaesthesia-induced atel-
ectasis was defined as localised sonographic consolidation
(subpleural tissue-like pattern). Air bronchograms may be
observed as bright echogenic branching structures within
such consolidations.
10
For a given thoracic area, points were allocated to the
worst LUS pattern observed: N¼0, B1¼1, B2¼2 and
C¼3. The sum of the points obtained in all the 12 lung
areas defined the LUS aeration score, ranging from 0 to 36
for the whole thorax. This score is inversely proportional
to the degree of lung aeration.
Protocol
The children were randomised into two groups before
surgery, using a randomisation table, (StatsDirect versio
´n
2.7.2; Altrincham, Cheshire, United Kingdom):
Control group (C-group): patients received the standard
protective ventilatory setting as described in the anaes-
thesia section.
Lung recruitment manoeuvre group (RM-group): patients
received a recruitment manoeuvre after baseline record-
ings and before the induction of capnoperitoneum. The
recruitment manoeuvre was performed in a pressure-
controlled mode with a constant driving pressure of
15 cmH
2
O. PEEP was increased in steps of 5 cmH
2
O,
from 5 to 15 cmH
2
O, every three breaths. The target
recruitment pressure of 30 cmH
2
O was maintained for 10
breaths, corresponding to approximately 30 s. The stan-
dard protective ventilatory settings were then applied
with 8 cmH
2
O of PEEP, to keep the lungs open after lung
recruitment. Recruitment manoeuvres were stopped
immediately if mean arterial pressure and/or heart rate
changed by at least 15% from baseline values.
Patients were studied in three consecutive steps:
Before capnoperitoneum: 5 min after anaesthesia induction.
After baseline recordings, the recruitment manoeuvre
was performed in the RM-group.
During capnoperitoneum: Capnoperitoneum pressure was
kept at 1.3 kPa during the entire capnoperitoneum
period (Endoflator; Karl Storz, Tuttlingen, Germany)
and measurements were performed 20 min after starting
the capnoperitoneum.
After capnoperitoneum: 5 min after the end of surgery.
The same investigator performed LUS at each time point
of the study. Respiratory and cardiovascular data were
collected during each protocol step.
Statistical analysis
The null hypothesis was that atelectasis during the
capnoperitoneum would be similar between the two
groups and during the three episodes studied. Consider-
ing a beta-power of 80% and an alpha-error of 5%, the
statistical power to reject this hypothesis was calculated
assuming that atelectasis would be present in 90% of
patients in the C-group and in only 45% of patients in the
RM-group.
10
A sample size of 21 patients per group was
estimated. Descriptive data are presented as n(%) for
proportions and mean "SD or median for continuous
variables.
Univariate comparisons between groups were performed
for the three protocol episodes employing the ttest
for continuous variables (age, weight and duration of
surgery) and the Fisher exact test for the remaining
categorical variables. Within-group comparisons for
the three episodes studied, for each of the two groups,
were made using a ttest for repeated measurements
and a Bonferroni correction. Multiple linear mixed mod-
els were adjusted to examine the influence of recruit-
ment manoeuvres, age and duration of surgery
(covariates) on the aeration score and on each cardiovas-
cular variable treating them as a triple-variate response
(repeated measures). A second model, a generalised
linear mixed model with an ordinal variable as the
response, was fitted to analyse the influence of treatment
and personal data on lung aeration during the three
episodes studied.
APvalue less than 0.05 was considered statistically
significant. All calculations were performed using the
R statistical package (R Core Team, 2015, Foundation
for Statistical Computing, Vienna, Austria).
Results
We enrolled 47 children with ASA physical status I–II,
aged 46 "27 months. Five patients were excluded
(Fig. 1). All had similar personal characteristics and
surgical duration (Table 1).
The aeration scores obtained in the two groups during the
three steps of the study are illustrated in Fig. 2. After the
induction of anaesthesia and before capnoperitoneum,
the RM-group and C-group had similar scores for aeration
(P¼0.514). The scores decreased in the RM-group dur-
ing capnoperitoneum and after capnoperitoneum when
compared with the C-group (both P<0.001).
The generalised linear mixed model analysing the influ-
ence of treatment and personal data on the change in
aeration across the three protocol steps, revealed an
aeration trajectory in which weight (coefficient 0.073,
P¼0.016), age (coefficient 0.043, P<0.001) and recruit-
ment manoeuvres (coefficient 0.879, P<0.001) influ-
enced lung aeration in the most dependent lung areas
only.
Lung recruitment during laparoscopy in children 575
Eur J Anaesthesiol 2018; 35:573– 580
Copyright © European Society of Anaesthesiology. Unauthorized reproduction of this article is prohibited.
Table 2 presents the incidence of a specific pattern for
atelectasis in both groups. We found a significant differ-
ence in atelectasis during capnoperitoneum between the
two groups (P<0.001), and this difference was main-
tained to the end of anaesthesia (P<0.001). Figure 3 and
the Supplemental video, http://links.lww.com/EJA/A137
show examples of LUS images for one representative
patient per group.
The recruitment manoeuvre was well tolerated haemo-
dynamically and was not stopped in any of the children.
Table 3 gives the cardiovascular variables and Cdyn.
All variables remained stable in both groups, except
for SpO
2
and Cdyn. The latter was 23% higher in the
RM-group than in the C-group after capnoperitoneum
(P<0.001).
The linear mixed models showed that the recruitment
manoeuvre and age affected the trajectories of the aera-
tion score (both, P<0.001) and that age affected the
trajectory of Cdyn (P<0.001). The duration of surgery
and all the other variables studied had no influence on the
trajectories of aeration score.
Discussion
The current study documents the high incidence of
lung collapse in anaesthetised children undergoing
laparoscopy. The negative effect of anaesthesia and
576 Acosta et al.
Fig. 1
Enrolment
Allocation
Follow-up
Analysis
Declined to participat e (n = 3)
Acute airways infection (n = 2)
Assigned to C-group (n = 21)
No additional intervention (n = 21)
Assigned to RM-group (n = 21)
Received allocat ed intervention (n = 21)
Patients analysed (n = 21) Patients analysed (n = 21)
Lost to follow-up (n = 0)
Discontinued intervention (n = 0)
Lost to follow-up (n = 0)
Discontinued intervention (n = 0)
Patients assessed
(n = 47)
Underwent randomisation
(n = 42)
Flow chart.
Table 1 Personal characteristics
RM-group, nU21 C-group, nU21 Pvalue
M
Age (months) 49 "27 43 "27 0.47
Sex
Male 18 (86) 18 (86) 1.00
M
Female 3 (14) 3 (14)
Weight (kg) 18.9 "6.9 18.1 "6.8 0.70
ASA classification
1 18 (86) 19 (90) 1.00
M
2 3 (14) 2 (10)
Type of surgery n(%)
Herniorrhaphy 12 (57) 14 (66)
Orchidopexy 1 (5) 1 (5)
Herniorrhaphy þorchidopexy 6 (29) 6 (29) 1.00
M
Mitrofanoff surgery 1 (5) 0 (0)
Nissen fundoplication 1 (5) 0 (0)
Duration (min) 62 "13 61 "11 0.74
ASA classification, American Society of Anesthesiologists classification; C-group, control group; RM-group, lung recruitment manoeuvre group. Data are presented as
n(%) for proportions and as mean "SD for continuous variables.
M
Fisher’s exact test.
Eur J Anaesthesiol 2018; 35:573–580
Copyright © European Society of Anaesthesiology. Unauthorized reproduction of this article is prohibited.
capnoperitoneum on lung aeration persisted in the chil-
dren treated with standard protective ventilator strategy.
In contrast, in most patients treated with a recruitment
manoeuvre followed by 8 cmH
2
O of PEEP, the develop-
ment of atelectasis was prevented during and after
capnoperitoneum.
LUS has great potential as it represents a radiation-free,
noninvasive and reliable tool for assessing lung aeration at
the bedside.
24,25
When compared with magnetic reso-
nance imaging, LUS showed high sensitivity (88%), spec-
ificity (89%) and accuracy (88%) for diagnosing
anaesthesia-induced atelectasis in children.
10
These
results were similar to those observed by Yu et al.
26
in
anesthetised adults, who showed good sensitivity (87%),
specificity (92%) and accuracy (91%) in verifying the
occurrence of atelectasis by LUS in comparison with
computed tomography (CT)-scan as the reference
method. The number of B-lines, well known LUS artefacts
related to a deterioration in lung aeration, also correlated
with the extent of parenchymal changes on CT scans in
children.
27
The LUS aeration score described by Soum-
mer et al.
20
and Bouhemad et al.
24
is a well established and
validated method for evaluating the condition of lung
aeration and monitoring its changes over time. The same
LUS method has already been tested in anaesthetised
adults undergoing laparoscopy.
19,21
.
Lung collapse during anaesthesia ranges from slight loss
in aeration to complete acinar collapse in the most
dependent areas of the lungs.
1,2,6– 10
We found that the
majority of our patients showed atelectasis immediately
after the induction of anaesthesia. This high incidence of
lung collapse is similar to that found in previous studies
during nonlaparoscopic
6– 11
and laparoscopic
21
proce-
dures. We also observed that the aeration score and
atelectasis increased during and after capnoperitoneum
in the C-group but decreased in the RM-group (Table 2
and Fig. 2).
Our findings support the common belief that capnoper-
itoneum can increase atelectasis, possibly due to lung
compression caused by a cranial shift of the diaphragm.
Another possible explanation for this phenomenon of loss
of aeration is the time effect. Lutterbey et al.
9
described a
12% increase in the amount of atelectasis during 85 min
of general anaesthesia. Indeed, in the C-group, we have
observed that the extension of atelectasis doubled (23%)
only 20 min after reaching the target capnoperitoneum
Lung recruitment during laparoscopy in children 577
Fig. 2
20
15
10
Score of aeration
5
0
60
40
30
50
Crs (ml cmH2O–1)
20
10
0
C-group
#**
*
Before
CP
During
CP
After
CP
RM-group
Box plot for the score of aeration and dynamic respiratory compliance
during the study. The thick line across the box represents the median, the
ends of box represent the 25th and 75th percentiles, the whiskers
represent the range, excluding the data shown as o. The latter are outliers,
1.5 times the interquartile range above the upper quartile and bellow the
lower quartile.
%
Differences between groups in each moment according
to ttest for independent samples with Pvalues less than 0.05 considered
significant.
#
Within-group differences between moments of the protocol
according to ttest for repeated measurements with Bonferroni correction
with Pvalues less than 0.025 considered significant.
Table 2 Incidence of atelectasis per group and per protocol step as assessed by lung ultrasound
Protocol step RM-group, nU21
M
Pvalue C-group, nU21
M
Pvalue
MM
Pvalue
Before CP n (%) 13 (62) 12 (57) 0.750
During CP n (%) 4 (19) 0.003 17 (80) 0.100 <0.001
After CP n (%) 5 (24) 0.715 18 (85) 0.687 <0.001
Data are presented as n(%) for the incidence of atelectasis. C-group, control group; CP, capnoperitoneum; RM-group, lung recruitment manoeuvre group.
M
ttest
comparing differences within the individual study groups at successive times: Before CP% vs. During CP%, During CP% vs. After CP%
MM
Fisher’s exact test for
comparisons between groups in each protocol step.
Eur J Anaesthesiol 2018; 35:573– 580
Copyright © European Society of Anaesthesiology. Unauthorized reproduction of this article is prohibited.
pressure. It is probable that capnoperitoneum, rather than
the time-effect, is the cause of loss of lung aeration in our
children undergoing laparoscopy. Further support for this
hypothesis comes from the generalised linear mixed
model, as the development of aeration during the pro-
cedures was not affected by the time course of surgery.
The linear mixed model also revealed that age and body
weight (related to age) affected the trajectory of lung
aeration. This result is in agreement with the findings of
other authors who showed that the severity of atelectasis
induced by anaesthesia in children decreases with
age.
4,5,9,11
We performed the recruitment manoeuvre before capno-
peritoneum, and not during laparoscopy, because the
increase in intra-abdominal pressure generated by cap-
noperitoneum would have been transmitted, in part, to
the pleural space,
28,29
increasing the pulmonary plateau
pressure beyond 30 cmH
2
O, the maximum pressure
recommended for lung recruitment manoeuvres in
children.
Following recruitment manoeuvres, the level of PEEP
that prevents lung recollapse during capnoperitoneum in
children is unknown. In anaesthetised children without
capnoperitoneum, 5 cmH
2
O of PEEP applied after a
recruitment manoeuvres kept the lungs open in some
studies but failed to obtain similar beneficial effect in
others.
8,9
The current data suggest that a PEEP fixed at
8 cmH
2
O was not enough to prevent the lungs from
recollapsing in all RM-group patients (Table 2 and
Fig. 2). We hypothesise that PEEP levels higher than
the usual 5 cmH
2
O applied in studies on anaesthetised
patients would be required to preserve normal lung
aeration during capnoperitoneum. It should be noted
that the quoted studies were not intended to evaluate
the best ventilator strategy to prevent the additional
effects of capnoperitoneum.
8,9
Following a recruitment manoeuvre, it is possible to
personalise the PEEP level by using a PEEP titration
trial, something that has been well described for experi-
mental models and for anaesthetised adults.
30– 32
The
578 Acosta et al.
Table 3 Respiratory and cardiovascular data
Before CP During CP After CP
Variable RM-group C-group RM-group C-group RM-group C-group
HR (bpm) 108 "15 114 "12 99 "17 103 "15 95 "17 100"16
MAP (kpa) 8.3 "0.9 8.1 "0.9 8.3 "0.9 8.4 "0.9 8.4 "0˙78.4"0.5
SpO
2
(%) 98 "0.9 99 "0.5 99 "0.6 98 "0.7
M
99 "0.7 98 "0.6
MM
PETCO
2
(kpa) 5.6 "0˙4 5.6 "0˙4 5.7 "0.5 5.7 "0˙4 5.3 "0˙5 5.5 "0˙5
Cdyn (ml cmH
2
O
#1
)23"922"621"917"528"10 20 "5
MM
All data are presented as mean "SD. Cdyn, respiratory system dynamic compliance; C-group, control group; CP, capnoperitoneum; HR, heart rate in beats per minute;
MAP, mean arterial pressure; PETCO
2
, end-tidal partial pressure of CO
2
;RM-group,lungrecruitmentmanoeuvregroup;SpO
2
,pulseoximetry.
M
P¼0.009.
MM
P<0.001
(ttest).
Fig. 3
Before CP During CP Af ter CP
C-groupRM-group
Lung ultrasound images of one representative patient per group during the protocol. C-group, control group; CP, capnoperitoneum; RM-group, lung
recruitment manoeuvre group.
Eur J Anaesthesiol 2018; 35:573–580
Copyright © European Society of Anaesthesiology. Unauthorized reproduction of this article is prohibited.
level of PEEP to apply after a recruitment manoeuvre to
achieve best lung function depends on individual and
surgical factors. Thus, 5 cmH
2
O of PEEP was enough for
paediatric and some adult patients without capnoperito-
neum, but higher PEEP levels were necessary for tho-
racic procedures [10 "2 cmH
2
O] and the morbidly obese
(15 to 16 cmH
2
O).
16,31,32
To match PEEP to an anaes-
thetised child undergoing laparoscopy, a PEEP titration
trial should be performed immediately after actively
recruiting the lungs.
The clinical implication of our findings in children is that
a recruitment manoeuvre can reduce the amount of lung
collapse induced by the deleterious combination of gen-
eral anaesthesia and capnoperitoneum. However, the
transmission of pressure to the pleural space caused by
capnoperitoneum probably demands a ventilator strategy
based on higher PEEP levels than usual to maintain a
beneficial recruitment effect. The optimisation of PEEP
strategy based on a PEEP titration trial after a recruit-
ment manoeuvres should be considered during laparo-
scopic procedures. Future studies should determine the
point of lung recollapse and explore therapeutic PEEP
levels in patients undergoing capnoperitoneum.
Limitations
Our study has some limitations. One pitfall in the protocol
is the lack of baseline LUS images before induction of
anaesthesia. The unlikely compliance of awake children in
the stressful situation preceding surgery reduces the fea-
sibility of a routineexamination. We made the assumption
that our children had normal lung aeration before anaes-
thesia because only the healthy were enrolled.
Another limitation of our study is the lack of LUS
examination after recruitment manoeuvres and before
capnoperitoneum in the treatment group. We limited
the number of LUS examinations in an attempt to mini-
mise the additional anaesthesia time created by our
study. As a result, we are now unable to clarify whether
the remaining atelectasis seen in this group was caused by
inefficiencies of the recruitment manoeuvres, capnoper-
itoneum-induced additional lung collapse or a combina-
tion of both effects.
Our study lacks data on the interoperator variability in the
assessment of LUS, but the ultrasound examinations were
performed by an operator who might be considered an
advanced expert in LUS. Accordingly, we cannot com-
ment on the degree of variability of the technique. How-
ever, the ultrasound score used in the study relies on very
basic and simple pattern recognition and previous reports
have already demonstrated a low variability of the
technique.
Conclusion
Anaesthesia-induced atelectasis was present in the major-
ity of children with healthy lungs. In most cases,
additional lung collapse caused by capnoperitoneum
may have been successfully prevented by recruitment
manoeuvres and PEEP. This ventilatory strategy was
haemodynamically well tolerated in children with normal
lungs and cardiac function.
Acknowledgements relating to this article
Assistance with the study: we thank Rita Ceschi for her
technical assistance.
Financial support and sponsorship: local hospital resources.
Conflict of interest: none.
Presentation: none.
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