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Effects of fixed compared to automatic CPAP on sleep in Obstructive Sleep Apnoea Syndrome

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Onofrio Resta at Università degli Studi di Bari Aldo Moro
Onofrio Resta
Pierluigi carratù at Università degli Studi di Bari Aldo Moro
Pierluigi carratù
  • Università degli Studi di Bari Aldo Moro
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Automatic CPAP has been developed to improve CPAP efficiency and compliance. Continually matching the effective pressure may be associated to more frequent arousals that could disturb sleep. The aim of the present study was to compare sleep architecture after one month's home therapy with CPAP or with an AutoCPAP device. Twenty OSAS patients (18 M / 2 F) after polysomnographic study with CPAP titration received either an automatic (AutoSet T, ResMed, Sydney, Australia) or a fixed level CPAP machine in a random, single blind fashion for one month. At the end of the home treatment period polysomnography was repeated while CPAP was administered by the same machine used at home. There was no significant difference between groups in terms of age (50.0 vs 45.5, NS), sex, BMI (38.3 vs 35.1, NS), RDI (45.4 vs 48.0, NS), and CPAP effective level (9.8 vs 10.8, NS). After one month of therapy the correction of sleep respiratory disturbances and of sleep structure was satisfactory in both groups. No difference in any polysomnographic variable or in subjective sleepiness was found at re-evaluation. The results of this study demonstrate that on average CPAP administered by a fixed CPAP machine and by the AutoSet T autoCPAP device has similar effects in improving respiratory function during sleep, nocturnal sleep architecture, and subjective daytime sleepiness after a one-month therapy. As autoCPAP devices are more expensive than fixed CPAP machines, their prescription should be considered only after a clear demonstration of an increase in compliance to treatment by these devices.
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Effects of fixed compared to automatic CPAP on sleep in Obstructive Sleep Apnoea Syndro
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... Twenty-two trials reported ESS after treatment (Figure 4)10111213141516171819202122232425262729,30,32,33] . No statistically significant differences in ESS were observed between APAP and CPAP in 20 trials, while two studies reported a significant decrease in ESS favoring APAP [23,30]. ...
... Meta-analysis of nine trials showed a non-significant difference in arousal index of -0.85 events/hour (95% CI, -2.2 to 0.5 events/hour; P = 0.23), favoring APAP (Figure 5) [10,12,14,20,24,26,29,31,32]. Meta-analysis of nine trials showed a statistically significant difference in minimum oxygen saturation of -1.3% (95% CI, -2.2 to -0.4%; P = 0.003), favoring CPAP (Figure 6)12131416,20,24,26,31,32]. ...
... Meta-analysis of nine trials showed a non-significant difference in arousal index of -0.85 events/hour (95% CI, -2.2 to 0.5 events/hour; P = 0.23), favoring APAP (Figure 5) [10,12,14,20,24,26,29,31,32]. Meta-analysis of nine trials showed a statistically significant difference in minimum oxygen saturation of -1.3% (95% CI, -2.2 to -0.4%; P = 0.003), favoring CPAP (Figure 6)12131416,20,24,26,31,32]. Neither meta-analysis had statistically significant heterogeneity . ...
Auto-titrating versus fixed continuous positive airway pressure for the treatment of obstructive sleep apnea: A systematic review with meta-analyses
Article
Full-text available
  • Mar 2012
Obstructive sleep apnea is a relatively common disorder that can lead to lost productivity and cardiovascular disease. The form of positive airway treatment that should be offered is unclear. MEDLINE and the Cochrane Central Trials registry were searched for English language randomized controlled trials comparing auto-titrating positive airway pressure (APAP) with continuous positive airway pressure (CPAP) in adults with obstructive sleep apnea (inception through 9/2010). Six researchers extracted information on study design, potential bias, patient characteristics, interventions and outcomes. Data for each study were extracted by one reviewer and confirmed by another. Random effects model meta-analyses were performed for selected outcomes. Twenty-four randomized controlled trials met the inclusion criteria. In individual studies, APAP and fixed CPAP resulted in similar changes from baseline in the apnea-hypopnea index, most other sleep study measures and quality of life. By meta-analysis, APAP improved compliance by 11 minutes per night (95% CI, 3 to 19 minutes) and reduced sleepiness as measured by the Epworth Sleepiness Scale by 0.5 points (95% CI, 0.8 to 0.2 point reduction) compared with fixed CPAP. Fixed CPAP improved minimum oxygen saturation by 1.3% more than APAP (95% CI, 0.4 to 2.2%). Studies had relatively short follow-up and generally excluded patients with significant comorbidities. No study reported on objective clinical outcomes. Statistically significant differences were found but clinical importance is unclear. Because the treatment effects are similar between APAP and CPAP, the therapy of choice may depend on other factors such as patient preference, specific reasons for non-compliance and cost.
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... All ACP clinical practice guidelines are considered automatically withdrawn or invalid 5 years after publication, or once an update has been issued. (59,60,189,190,(192)(193)(194) ...
Management of Obstructive Sleep Apnea in Adults: A Clinical Practice Guideline From the American College of Physicians
Article
Full-text available
  • Sep 2013
  • ANN INTERN MED
The American College of Physicians (ACP) developed this guideline to present the evidence and provide clinical recommendations on the management of obstructive sleep apnea (OSA) in adults. This guideline is based on published literature from 1966 to September 2010 that was identified by using MEDLINE, the Cochrane Central Register of Controlled Trials, and the Cochrane Database of Systematic Reviews. A supplemental MEDLINE search identified additional articles through October 2012. Searches were limited to English-language publications. The clinical outcomes evaluated for this guideline included cardiovascular disease (such as heart failure, hypertension, stroke, and myocardial infarction), type 2 diabetes, death, sleep study measures (such as the Apnea-Hypopnea Index), measures of cardiovascular status (such as blood pressure), measures of diabetes status (such as hemoglobin A1c levels), and quality of life. This guideline grades the evidence and recommendations using ACP's clinical practice guidelines grading system. RECOMMENDATION 1: ACP recommends that all overweight and obese patients diagnosed with OSA should be encouraged to lose weight. (Grade: strong recommendation; low-quality evidence) RECOMMENDATION 2: ACP recommends continuous positive airway pressure treatment as initial therapy for patients diagnosed with OSA. (Grade: strong recommendation; moderate-quality evidence) RECOMMENDATION 3: ACP recommends mandibular advancement devices as an alternative therapy to continuous positive airway pressure treatment for patients diagnosed with OSA who prefer mandibular advancement devices or for those with adverse effects associated with continuous positive airway pressure treatment. (Grade: weak recommendation; low-quality evidence).
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Titration studies overestimate continuous positive airway pressure requirements in uncomplicated obstructive sleep apnea
Article
  • May 2021
Study objectives: Attended manual CPAP titration is the standard practice for determining optimal positive airway pressures for OSA treatment. However, an unattended single night auto-titrating positive airway pressure (APAP) titration is an alternative. The goal of this study was to determine whether therapeutic CPAP pressures determined during manual titrations are higher than APAP generated surrogate pressures. Methods: We conducted a retrospective review of 165 adults with uncomplicated OSA who had full/split-night manual CPAP titrations prior to commencing treatment with APAP. Demographic and clinical data including 30-day APAP compliance data were obtained. We compared the recommended CPAP pressure from manual titrations with the 90th/95th percentile pressure generated from APAP usage over 30 days. Results: The recommended CPAP pressures during the manual titrations were higher than the 90th/95th percentile pressures generated from APAP. (11.4 ± 3.4 vs. 10.3 ± 2.4, p=0.000). Almost half the group (41.9%) had their manually derived titration pressure at least 1.5 cm above the 90th/95th percentile pressure. In multivariate analyses, BMI was the only variable that predicted higher manual titration pressures. Notably, the average residual AHI on 30-day APAP data was less than the average residual AHI observed at the recommended pressure during the manual titration (5.0 ± 4.3 vs. 7.2 ± 8.5, p= 0.006). Conclusions: Manual CPAP titrations may overestimate pressure requirements particularly in patients with higher BMI and may not be necessary in managing patients with uncomplicated OSA. APAP appears to be at least as effective as single pressure CPAP, while delivering lower positive airway pressure.
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Baseline Lighter Sleep and Lower Saturation Are Associated With Improved Sleepiness and Adherence on Continuous Rather Than Autotitrating Positive Airway Pressure
Article
  • Dec 2019
The objective was to test whether there were better outcomes on switching from autotitrating positive airway pressure (APAP) to continuous positive airway pressure (CPAP) in a clinic sample of patients with obstructive sleep apnea (OSA). Patients prescribed APAP in 2015-2016 and belonging to a subset characterized by side effects, or suboptimal response or adherence, were advised a switch to CPAP following a CPAP titration polysomnography. The main analysis was for improvement (after switch from APAP to CPAP) in (1) sleepiness, wakefulness inability, and fatigue, using change from baseline in the Sleepiness–Wakefulness Inability and Fatigue Test (delta SWIFT), and Epworth Sleepiness Scale (delta ESS), and (2) adherence using percentage of days with ≥4-hour use and whether there was ≥4-hour use on ≥70% days. To determine possible predictors for switching, additional analysis was performed for differences at baseline between patients switching and those staying on APAP. A total of 148 patients were switched from APAP to CPAP and had greater improvement in delta SWIFT (5.2 vs 4.1, P = .004), greater improvement in delta ESS (3.6 vs 2.9, P = .011), and better adherence (79.4% vs 74.3%, P = .006) on CPAP than on APAP. More patients were adherent on CPAP than on APAP (83.1% vs 68.9%, P = .006). Patients switching had higher baseline arousal index and stage N1 sleep, and lower nadir oxygen saturation, than 96 patients not switching. Thus, there is a subset of patients with better outcomes after switching to CPAP than on APAP. Patients with baseline lighter sleep (indicated by more arousals and stage N1), or greater desaturation, may be more likely to do better on CPAP than on APAP. CPAP may be the preferable treatment in a significant subset of patients. If APAP is used first anyway, side effects, or suboptimal response or adherence, should lead to consideration of switching to CPAP based on a CPAP titration polysomnography.
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Pressure modification or humidification for improving usage of continuous positive airway pressure machines in adults with obstructive sleep apnoea
Article
  • Dec 2019
Background: Obstructive sleep apnoea (OSA) is the repetitive closure of the upper airway during sleep. This results in disturbed sleep and excessive daytime sleepiness. It is a risk factor for long-term cardiovascular morbidity. Continuous positive airway pressure (CPAP) machines can be applied during sleep. They deliver air pressure by a nasal or oronasal mask to prevent the airway from closing, reducing sleep disturbance and improving sleep quality. Some people find them difficult to tolerate because of high pressure levels and other symptoms such as a dry mouth. Switching to machines that vary the level of air pressure required to reduce sleep disturbance could increase comfort and promote more regular use. Humidification devices humidify the air that is delivered to the upper airway through the CPAP circuit. Humidification may reduce dryness of the throat and mouth and thus improve CPAP tolerability. This updated Cochrane Review looks at modifying the delivery of positive pressure and humidification on machine usage and other clinical outcomes in OSA. Objectives: To determine the effects of positive pressure modification or humidification on increasing CPAP machine usage in adults with OSA. Search methods: We searched Cochrane Airways Specialised Register and clinical trials registries on 15 October 2018. Selection criteria: Randomised parallel group or cross-over trials in adults with OSA. We included studies that compared automatically adjusting CPAP (auto-CPAP), bilevel positive airway pressure (bi-PAP), CPAP with expiratory pressure relief (CPAPexp), heated humidification plus fixed CPAP, automatically adjusting CPAP with expiratory pressure relief, Bi-PAP with expiratory pressure relief, auto bi-PAP and CPAPexp with wakefulness detection with fixed pressure setting. Data collection and analysis: We used standard methods expected by Cochrane. We assessed the certainty of evidence using GRADE for the outcomes of machine usage, symptoms (measured by the Epworth Sleepiness Scale (ESS)), Apnoea Hypopnoea Index (AHI), quality of life measured by Functional Outcomes of Sleep Questionnaire (FOSQ), blood pressure, withdrawals and adverse events (e.g. nasal blockage or mask intolerance). The main comparison of interest in the review is auto-CPAP versus fixed CPAP. Main results: We included 64 studies (3922 participants, 75% male). The main comparison of auto-CPAP with fixed CPAP is based on 36 studies with 2135 participants from Europe, USA, Hong Kong and Australia. The majority of studies recruited participants who were recently diagnosed with OSA and had not used CPAP previously. They had excessive sleepiness (ESS: 13), severe sleep disturbance (AHI ranged from 22 to 59), and average body mass index (BMI) of 35 kg/m2. Interventions were delivered at home and the duration of most studies was 12 weeks or less. We judged that studies at high or unclear risk of bias likely influenced the effect of auto-CPAP on machine usage, symptoms, quality of life and tolerability, but not for other outcomes. Primary outcome Compared with average usage of about five hours per night with fixed CPAP, people probably use auto-CPAP for 13 minutes longer per night at about six weeks (mean difference (MD) 0.21 hours/night, 95% confidence interval (CI) 0.11 to 0.31; 31 studies, 1452 participants; moderate-certainty evidence). We do not have enough data to determine whether auto-CPAP increases the number of people who use machines for more than four hours per night compared with fixed CPAP (odds ratio (OR) 1.16, 95% CI 0.75 to 1.81; 2 studies, 346 participants; low-certainty evidence). Secondary outcomes Auto-CPAP probably reduces daytime sleepiness compared with fixed CPAP at about six weeks by a small amount (MD -0.44 ESS units, 95% CI -0.72 to -0.16; 25 studies, 1285 participants; moderate-certainty evidence). AHI is slightly higher with auto-CPAP than with fixed CPAP (MD 0.48 events per hour, 95% CI 0.16 to 0.80; 26 studies, 1256 participants; high-certainty evidence), although it fell with both machine types from baseline values in the studies. Ten per cent of people in auto-CPAP and 11% in the fixed CPAP arms withdrew from the studies (OR 0.90, 95% CI 0.64 to 1.27; moderate-certainty evidence). Auto-CPAP and fixed CPAP may have similar effects on quality of life, as measured by the FOSQ but more evidence is needed to be confident in this result (MD 0.12, 95% CI -0.21 to 0.46; 3 studies, 352 participants; low-certainty evidence). Two studies (353 participants) provided data on clinic-measured blood pressure. Auto-CPAP may be slightly less effective at reducing diastolic blood pressure compared to fixed CPAP (MD 2.92 mmHg, 95% CI 1.06 to 4.77 mmHg; low-certainty evidence). The two modalities of CPAP probably do not differ in their effects on systolic blood pressure (MD 1.87 mmHg, 95% CI -1.08 to 4.82; moderate-certainty evidence). Nine studies (574 participants) provided information on adverse events such as nasal blockage, dry mouth, tolerance of treatment pressure and mask leak. They used different scales to capture these outcomes and due to variation in the direction and size of effect between the studies, the comparative effects on tolerability outcomes are uncertain (very low-certainty evidence). The evidence base for other interventions is smaller, and does not provide sufficient information to determine whether there are important differences between pressure modification strategies and fixed CPAP on machine usage outcomes, symptoms and quality of life. As with the evidence for the auto-CPAP, adverse events are measured disparately. Authors' conclusions: In adults with moderate to severe sleep apnoea starting positive airway pressure therapy, auto-CPAP probably increases machine usage by about 13 minutes per night. The effects on daytime sleepiness scores with auto-CPAP are not clinically meaningful. AHI values are slightly lower with fixed CPAP. Use of validated quality of life instruments in the studies to date has been limited, although where they have been used the effect sizes have not exceeded proposed clinically important differences. The adoption of a standardised approach to measuring tolerability would help decision-makers to balance benefits with harms from the different treatment options available. The evidence available for other pressure modification strategies does not provide a reliable basis on which to draw firm conclusions. Future studies should look at the effects of pressure modification devices and humidification in people who have already used CPAP but are unable to persist with treatment.
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Treatment of Adult Obstructive Sleep Apnea with Positive Airway Pressure: An American Academy of Sleep Medicine Clinical Practice Guideline
Article
  • Feb 2019
Introduction: The purpose of this systematic review is to provide supporting evidence for the clinical practice guideline for the treatment of obstructive sleep apnea (OSA) in adults using positive airway pressure (PAP). Methods: The American Academy of Sleep Medicine commissioned a task force of experts in sleep medicine. A systematic review was conducted to identify studies that compared the use of PAP with no treatment as well as studies that compared different PAP modalities. Meta-analyses were performed to determine the clinical significance of using PAP in several modalities (ie, continuous PAP, auto-adjusting PAP, and bilevel PAP), to treat OSA in adults. In addition, meta-analyses were performed to determine the clinical significance of using an in-laboratory versus ambulatory strategy for the initiation of PAP, educational and behavioral interventions, telemonitoring, humidification, different mask interfaces, and flexible or modified pressure profile PAP in conjunction with PAP to treat OSA in adults. Finally, the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process was used to assess the evidence for making recommendations. Results: The literature search resulted in 336 studies that met inclusion criteria; 184 studies provided data suitable for meta-analyses. The data demonstrated that PAP compared to no treatment results in a clinically significant reduction in disease severity, sleepiness, blood pressure, and motor vehicle accidents, and improvement in sleep-related quality of life in adults with OSA. In addition, the initiation of PAP in the home demonstrated equivalent effects on patient outcomes when compared to an in-laboratory titration approach. The data also demonstrated that the use of auto-adjusting or bilevel PAP did not result in clinically significant differences in patient outcomes compared with standard continuous PAP. Furthermore, data demonstrated a clinically significant improvement in PAP adherence with the use of educational, behavioral, troubleshooting, and telemonitoring interventions. Systematic reviews for specific PAP delivery method were also performed and suggested that nasal interfaces compared to oronasal interfaces have improved adherence and slightly greater reductions in OSA severity, heated humidification compared to no humidification reduces some continuous PAP-related side effects, and pressure profile PAP did not result in clinically significant differences in patient outcomes compared with standard continuous PAP.
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Effekt von Kontrolluntersuchungen bei Patienten mit obstruktivem Schlafapnoe-Syndrom: Stellenwert der Bilevel- und automatischen CPAP-Therapie
Article
  • Dec 2008
Introduction Automatic positive airway pressure (APAP) and bilevel devices are used as alternatives to continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea syndrome (OSAS). However, the question still remains what the advantages of these options are or if there are special indications in patients with difficult to treat OSAS. Methods A Medline search was performed using the key words “bilevel OR bipap AND sleep apnea” and “APAP OR automatic CPAP AND sleep apnea”. For bilevel and APAP 14 studies for each were included in the further evaluation. Results and conclusions Both bilevel and APAP have proved to be equally effective as compared to CPAP. Therefore, CPAP still represents the standard treatment for OSAS. APAP is generally advantageous in terms of patients’ preference and individually in terms of compliance in patients with high pressure demand, side effects or insufficient treatment under constant CPAP. Bilevel appears to be beneficial in patients with central sleep apnea. Both options can provide sufficient therapy in patients with difficult to treat sleep apnea in which CPAP did not work. These indications and advantages might appear over the longer treatment term so that control visits to re-evaluate the efficacy and acceptance of the CPAP treatment are essential.
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Effect of automatic versus fixed continuous positive airway pressure for the treatment of obstructive sleep apnea: An up-to-date meta-analysis
Article
  • Dec 2011
  • SLEEP BREATH
Purpose: This study was made to evaluate the effect of automatic continuous positive airway pressure (auto-CPAP) versus fixed continuous positive airway pressure (fixed CPAP) in reducing the apnea-hypopnea index (AHI) and the mean therapy pressure, improving subjective sleepiness, sleep architecture, patient compliance, and preference in patients with obstructive sleep apnea. Methods: We searched the electronic databases MEDLINE, EMBASE, the Cochrane Library, and Google Scholar. Randomized controlled trials comparing auto-CPAP with fixed CPAP were reviewed. Continuous variables were presented as mean difference (MD), and dichotomous data as odds ratio (OR), both with 95% confidence intervals (CI). Results: We identified 19 studies consisting of 845 patients. Compared to fixed CPAP, the use of auto-CPAP reduced mean therapy pressure (MD -1.64; 95% CI -2.46 to -0.82), improved patient compliance (MD 0.23; 95% CI 0.06 to 0.39), increased the percentage of total sleep time (TST) in slow wave sleep (MD 5.11; 95% CI 1.34 to 8.88), and decreased the percentage of TST in stage 2 sleep (MD -4.75; 95% CI -9.38 to -0.11). Moreover, more patients preferred auto-CPAP therapy (OR 3.65; 95% CI 1.27 to 10.53). There were nonsignificant trends towards better outcomes with auto-CPAP for AHI and Epworth Sleepiness Scale (MD -0.43; 95% CI -1.10 to 0.23, and MD -0.24; 95% CI -0.74 to 0.25, respectively), though these are of questionable clinical significance. Conclusions: There are some aspects of clinical care, such as a mild improvement in compliance, patient preference, and sleep architecture that appear to favor the use of auto-CPAP compared to fixed CPAP. The clinical relevance of these findings requires further study.
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Use of conventional and self-adjusting nasal continuous positive airway pressure for treatment of severe obstructive sleep apnea syndrome - A comparative study
Article
Full-text available
  • Mar 1998
To compare conventional and self-adjusting nasal continuous positive airway pressure (nCPAP) therapy in patients with severe obstructive sleep apnea syndrome with respect to suppression of respiratory disturbances, quality of sleep, mean mask pressure, and patient compliance. Cohort study of consecutive patients with obstructive sleep apnea syndrome, single-blinded. Clinical sleep laboratory in Germany. Fifty patients (44 men, 6 women who ranged in age from 35 to 71 years) with polysomnographically confirmed severe obstructive sleep apnea syndrome (respiratory disturbance index [RDI], >20/h). After baseline polysomnography, patients were randomly treated with nCPAP either in conventional (group 1) or in automatically adjusting (group 2) mode. Three to 6 months after adjustment, all patients underwent polysomnography again. They also were examined with a portable monitoring device and received a questionnaire on subjective well-being and device evaluation. Anthropometric and respiratory data were comparable in both groups; body mass index had not changed significantly in the follow-up. RDI dropped by 91.5% (from 38.3+/- 13.9/h to 3.6+/-4.4/h) in conventional and by 93.6% (from 35.5+/-9.6/h to 2.4+/-1.6/h) in self-adjusting mode (statistically not significant [NS]). Sleep efficiency decreased by 4.0% in conventional and increased by 2.0% in self-adjusting mode (NS). In both groups, normal sleep structure was largely restored. Mean mask pressure was 8.1+/-2.5 cm H2O in group 1 and 6.5+/-1.7 cm H2O in group 2 (p<0.01). Patient compliance in terms of nights per week of mask appliance was better in the self-adjusting mode (5.7+/-0.7 to 6.5+/-0.4; p<0.01). Self-adjusting nCPAP demonstrates the same reliability in suppression of respiratory disturbances as fixed-mask pressure therapy. Sleep quality is slightly superior, patient compliance is highly significantly better.
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Effect of Weight Loss on Upper Airway Collapsibility in Obstructive Sleep Apnea
Article
Full-text available
  • Oct 1991
  • Am J Respir Crit Care Med
Previous investigators have demonstrated in patients with obstructive sleep apnea that weight reduction results in a decrease in apnea severity. Although the mechanism for this decrease is not clear, we hypothesize that decreases in upper airway collapsibility account for decreases in apnea severity with weight loss. To determine whether weight loss causes decreases in collapsibility, we measured the upper airway critical pressure (Pcrit) before and after a 17.4 +/- 3.4% (mean +/- SD) reduction in body mass index in 13 patients with obstructive sleep apnea. Thirteen weight-stable control subjects matched for age, body mass index, gender (all men), and non-REM disordered breathing rate (DBR) also were studied before and after usual care intervention. During non-REM sleep, maximal inspiratory airflow was measured by varying the level of nasal pressure and Pcrit was determined by the level of nasal pressure below which maximal inspiratory airflow ceased. In the weight loss group, a significant decrease in DBR from 83.3 +/- 31.0 to 32.5 +/- 35.9 episodes/h and in Pcrit from 3.1 +/- 4.2 to -2.4 +/- 4.4 cm H2O (p less than 0.00001) was demonstrated. Moreover, decreases in Pcrit were associated with nearly complete elimination of apnea in each patient whose Pcrit fell below -4 cm H2O. In contrast, no significant change in DBR and a minimal reduction in Pcrit from 5.2 +/- 2.3 to 4.2 +/- 1.8 cm H2O (p = 0.031) was observed in the "usual care" group. We conclude that (1) weight loss is associated with decreases in upper airway collapsibility in obstructive sleep apnea, and that (2) the resolution of sleep apnea depends on the absolute level to which Pcrit falls.
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The immediate effects of nasal continuous positive airway pressure treatment on sleep pattern in patients with obstructive sleep apnea
Article
  • Feb 1986
  • Electroencephalogr Clin Neurophysiol
We studied the immediate effects of continuous positive airway pressure (CPAP) applied nasally on the pattern of sleep in 12 patients, aged 30-58 years, with obstructive sleep apnea syndrome. All patients demonstrated a moderate to severe syndrome on the control night; apnea index ranged 28-83 apneas/h sleep. Nasal CPAP completely abolished all obstructive apneas and allowed apnea-free breathing in all 12 patients. Nasal CPAP had a marked effect on the sleep pattern. It significantly reduced stage I/II non-rapid eye movement (NREM) sleep and markedly increased stage III/IV NREM and REM sleep on the first treatment night. Stage I/II NREM sleep decreased from a control of 62.7 +/- 2.3% to 29.1 +/- 2.3% on the first treatment night. Stage III/IV NREM sleep increased from a control of 6.7 +/- 1.6% to 31.5 +/- 1.6%. The rebound in this sleep stage was especially marked in 3 patients aged 55-58 years. REM sleep increased from a control of 18.4 +/- 2.0% to 30.6 +/- 2.0% on the first treatment night. There was an increase in REM density. All patients were treated for another 2 nights and their sleep pattern analyzed on the third night. All sleep stages were still significantly different to the control night. The possible mechanisms involved are discussed.
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Tracheal and neck position influence upper airway dynamics by altering airway length
Article
  • Nov 1993
Upper airway obstruction during sleep is characterized by inspiratory airflow limitation and reductions in maximal inspiratory airflow (VImax). To determine how mechanical factors modulate VImax, we analyzed pressure-flow relationships obtained in the isolated upper airway of paralyzed cats. VImax and its determinants, the pharyngeal critical pressure (Pcrit) and the nasal resistance (Rn) upstream to the flow-limiting site (FLS), were measured as caudal tracheal displacement, neck position, and airway length were systematically varied. As the proximal tracheal stump was displaced caudally, graded increases in VImax from 145.3 +/- 90.8 (SD) to 285.9 +/- 117.5 ml/s (P < 0.02) and decreases in Pcrit from -3.0 +/- 3.0 to -9.5 +/- 3.4 cmH2O (P < 0.002) were seen without any significant change in Rn. During neck flexion, significant decreases in VImax from 192.1 +/- 68.5 to 87.2 +/- 48.4 ml/s (P = 0.001), increases in Pcrit from -5.3 +/- 2.03 cmH2O to -1.6 +/- 1.4 cmH2O (P < 0.001), and decreases in Rn from 29.7 +/- 12.2 cmH2O.l-1.s to 16.2 +/- 8.9 cmH2O.l-1.s (P < 0.001) were noted compared with the neutral or extended neck position. Relative to the neutral airway length, upper airway length was found to decrease by 1.15 +/- 0.14 cm during neck flexion and to lengthen by 0.45 +/- 0.12 cm during neck extension. When tracheal displacement and neck position were altered, VImax and Rn correlated directly and Pcrit correlated inversely with airway length (P < 0.001). We conclude that alterations in airflow mechanics with caudal tracheal displacement and changes in neck positions are primarily due to alterations in airway length.
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The Occurrence of Sleep-Disordered Breathing Among Middle-Aged Adults
Article
  • Apr 1993
Limited data have suggested that sleep-disordered breathing, a condition of repeated episodes of apnea and hypopnea during sleep, is prevalent among adults. Data from the Wisconsin Sleep Cohort Study, a longitudinal study of the natural history of cardiopulmonary disorders of sleep, were used to estimate the prevalence of undiagnosed sleep-disordered breathing among adults and address its importance to the public health. A random sample of 602 employed men and women 30 to 60 years old were studied by overnight polysomnography to determine the frequency of episodes of apnea and hypopnea per hour of sleep (the apnea-hypopnea score). We measured the age- and sex-specific prevalence of sleep-disordered breathing in this group using three cutoff points for the apnea-hypopnea score (> or = 5, > or = 10, and > or = 15); we used logistic regression to investigate risk factors. The estimated prevalence of sleep-disordered breathing, defined as an apnea-hypopnea score of 5 or higher, was 9 percent for women and 24 percent for men. We estimated that 2 percent of women and 4 percent of men in the middle-aged work force meet the minimal diagnostic criteria for the sleep apnea syndrome (an apnea-hypopnea score of 5 or higher and daytime hypersomnolence). Male sex and obesity were strongly associated with the presence of sleep-disordered breathing. Habitual snorers, both men and women, tended to have a higher prevalence of apnea-hypopnea scores of 15 or higher. The prevalence of undiagnosed sleep-disordered breathing is high among men and is much higher than previously suspected among women. Undiagnosed sleep-disordered breathing is associated with daytime hypersomnolence.
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Effects of mouth opening on airway collapsibility in normal sleep subjects
Article
  • Feb 1996
We investigated the influence of mouth opening on upper airway (UA) collapsibility in six healthy sleeping volunteers. UA collapsibility was measured during continuous negative airway pressure trials that consisted of the progressive decrease in pressure in a nasal mask, with simultaneous recording of esophageal pressure and instantaneous flow. Measurements were made under two experimental conditions: mouth closed (MC), and mouth open (MO). Cephalometric measurements were obtained with subjects awake in the same position for both experimental conditions. UA critical pressure (Pcrit) was derived from the relationship between the breath-by-breath values of the maximal inspiratory airflow and the corresponding mask pressure. Pcrit was significantly less negative during MO than during MC (MO, -12.7 +/- 4.8 cm H2O; MC, -16.4 +/- 6 cm H2O, mean +/- SD; p = 0.03). Mouth opening was associated with a significant increase in the total respiratory resistance (MO, 3.8 +/- 1.6 cm H2O/ml/s; MC, 3.0 +/- 1.6 cm H2O/ml/s-1, p = 0.03). Besides an increase in the distance between the teeth and a reduction in the distance between the hyoid bone and the mandible, no significant changes in cephalometric parameters were found between MO and MC. We conclude that mouth opening increases UA collapsibility during sleep and that mouth opening may contribute to the occurrence of sleep-related breathing abnormalities.
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