Impact of the sleep apnea management group clinic on positive airway pressure adherence

Sleep and Breathing - Positive airway pressure (PAP) adherence is critical for managing obstructive sleep apnea (OSA). We postulate that group-based Sleep Apnea Management (SAM) clinic,...     

Effect of continuous positive airway pressure vs placebo continuous positive airway pressure on sleep quality in obstructive sleep apnea

STUDY OBJECTIVES: Continuous positive airway pressure (CPAP) therapy has become the treatment of choice for obstructive sleep apnea (OSA). However, the efficacy of CPAP therapy has not been evaluated against a suitable control. We investigated the effectiveness of CPAP therapy in improving sleep quality in patients with OSA. We hypothesized that CPAP improves sleep quality. PATIENTS: Forty-eight CPAP-naive OSA patients were evaluated. None were receiving antihypertensive medications, and none had major medical illnesses. DESIGN: Patients were randomized to receive either CPAP or placebo CPAP (CPAP at an ineffective pressure) for 7 days in a double-blind fashion. Forty-one patients completed the protocol. Sleep quality variables, arousals, sleep arterial oxygen saturation (SaO(2)), and respiratory disturbance index (RDI) were assessed at baseline, after 1 day of treatment, and after 7 days of treatment. Repeated measures analysis of variance was used to evaluate the effects of treatment, time, and the interaction of the two. RESULTS: As expected, CPAP lowered RDI and number of arousals, and increased SaO(2) over time (p = 0.001). Contrary to expectations, both CPAP and placebo CPAP had comparable effects on sleep quality as assessed by sleep architecture, sleep efficiency, total sleep time, and wake after sleep onset time. CONCLUSIONS: This study confirms the effectiveness of CPAP in lowering the number of arousals and the RDI, and in raising SaO(2). However, our data suggest that short-term CPAP is no different than placebo in improving sleep architecture. Further evaluation of the effectiveness of CPAP using a suitable placebo CPAP in prospective randomized studies is needed     

Racial disparity in adherence to positive airway pressure among US veterans

Purpose

Despite advances in continuous positive airway pressure (CPAP) technology, compliance with CPAP therapy remains suboptimal. Studies conducted since the advent of objective CPAP recording have noted that African Americans (AA) may use CPAP less than Whites. We sought to confirm this finding among a large sample of veterans and examine effect modifiers of the differential usage.

Methods

A retrospective cohort of 233 AA and 1939 White Veterans Administration (VA) patients who had a sleep study between January 2003 and October 2006 and received CPAP therapy by the end of 2007. CPAP compliance was summarized at 2 weeks and 6 months post CPAP receipt.

Results

AAs were significantly less adherent than Whites even when controlling for age, gender, marital status, median household income for zip code, BMI, comorbidities, and obstructive sleep apnea (OSA) severity. AAs with severe OSA were 3 times more likely to use CPAP than AAs with mild/moderate OSA (p?≤?0.001); a much smaller but still statistically significant difference was seen for Whites.

Conclusions

CPAP compliance is considerably lower in AAs than in Whites, though severity of OSA modifies this association. These findings are not readily explained by differences in demographics or comorbidity.

     

Determinants of continuous positive airway pressure compliance in a group of Greek patients with obstructive sleep apnea

ObjectiveThe aim of the study was to investigate the patients' characteristics that correlate with greater compliance to CPAP use.MethodsPatients diagnosed with OSAHS and treated with CPAP, who had at least one follow-up visit in the Sleep Clinic during one year, were included in the study. Demographic data, history of symptoms, comorbidities, Body Mass Index (BMI), Epworth Sleepiness Scale questionnaire (ESS), were obtained from patients before and under CPAP use. All variables were correlated with average daily CPAP use. Objective and subjective compliance were estimated and a cut off point of 4.5 h/d was used to distinguish ‘more compliant’ from less ‘compliant’ patients.ResultsNinety eight patients, with a mean age (± SD) of 55.5 (± 11.1) years were examined. Patients' symptoms improved after CPAP use. The objective compliance was 5.3 ± 1.6 h/d whereas the subjective compliance was higher. Only 25% of patients were characterized as ‘more compliant’. Compliance was positively correlated in a significant way with age and female gender, and negatively correlated with neck circumference, preexisting nasal problems and minimum saturation during sleep. Patients with arterial hypertension showed a trend to better compliance. Weight gain was more frequently observed in ‘less compliant’ patients.ConclusionTo our knowledge this is the first study examining parameters of CPAP compliance in a Greek population of OSAHS patients. Age, gender and minimum saturation during sleep were related to better compliance whereas higher neck circumference and preexisting nasal problems were the parameters related to a worse adherence to treatment.     

Determinants of continuous positive airway pressure compliance in a group of Chinese patients with obstructive sleep apnea.

OBJECTIVE: To assess continuous positive airway pressure (CPAP) compliance and factors associated with CPAP compliance among Chinese patients with obstructive sleep apnea (OSA). DESIGN: A prospective study of 112 consecutive patients with newly diagnosed OSA commencing CPAP treatment. SETTING: A university teaching hospital. Measurements and results: The following factors were evaluated for any correlation with objective CPAP compliance (effective mask pressure [hours per day]) at 1 month and 3 months: age, baseline apnea-hypopnea index (AHI), common OSA symptoms, minimum arterial oxygen saturation (SaO(2)), mean SaO(2), arousal index (AI), Epworth sleepiness scale (ESS), education level, CPAP levels, satisfaction with CPAP, side effects, and machine cost. There were 101 male and 11 female patients, with a mean (+/- SD) age of 45.6 +/- 1.2 years; body mass index, 29.3 +/- 5.2 kg/m(2); AI, 60 +/- 18/h; AHI, 48 +/- 24/h; minimum SaO(2) of 70 +/- 17%; and mean SaO(2) of 86 +/- 7%. ESS fell from 12.9 +/- 4.0 (baseline) to 5.2 +/- 4.7 at 3 months (p < 0.001). Objective CPAP compliance was 5.4 +/- 1.6 h/d and 5.3 +/- 1.6 h/d, while 75% and 72% of our patients were using CPAP objectively for > or = 4 h/d and at least 70% of the nights per week at 1 month and 3 months, respectively. Following univariate analysis of variance, a high baseline AHI (p = 0.006 and p = 0.004) was associated with higher objective CPAP compliance at 1 month and 3 months, respectively. CONCLUSION: CPAP usage and compliance were high in this patient population. A high baseline AHI was the only significant independent predictor of better CPAP compliance.     

Prediction of continuous positive airway pressure in obstructive sleep apnea

Continuous positive airway pressure (CPAP) prediction formulas can potentially simplify the treatment of obstructive sleep apnea (OSA). However, they can be difficult to derive and validate. We tested a statistical method to derive and validate a CPAP prediction formula using the same sample population. Seventy-six OSA patients underwent polysomnography and CPAP titration. Anthropometric measures, sleep parameters, and the Epworth sleepiness scale (ESS) were evaluated as predictors. All subsets regression was used to determine the optimum number of variables in the model. The Bayes information criterion was used to find the best-fit model. The model was then evaluated by a tenfold cross-validation procedure. Subjects were obese (BMI 31.3 ± 5.4) and had significant daytime somnolence (ESS 11.9 ± 5). Mean respiratory disturbance index (RDI) was 53.5 ± 31.3. The ESS was not predictive of titrated CPAP. The best-fit model included three variables (CPAP_pred = 30.8 + RDI × 0.03 − nadir saturation × 0.05 − mean saturation × 0.2). This model explained 67% of the variance. Our data and the literature suggest that a combination of two to three factors is predictive of titrated CPAP: RDI, oxyhemoglobin saturation, and obesity. Except for RDI, the specific factors vary in each population. A CPAP prediction formula that explains a high proportion of the titrated CPAP variance can be easily derived from parameters measured during the diagnostic work-up of OSA patients using a unique statistical model that allows derivation and validation of the formula in the same test population.     

Central sleep apnea reversed by continuous positive airway pressure

Continuous positive airway pressure (CPAP) is an accepted and highly effective method used in the treatment of obstructive sleep apnea (OSA). We have explored the potential utility of CPAP in a patient with sleep apnea without a major contribution of airway obstruction as measured by the usual criteria. The patient showed dramatic clinical and laboratory improvement in central apnea when treated with CPAP. A low level of CPAP (7.5 cm H2O) resulted in the reduction of central apneas from 281 to 32 per night with no significant change in obstructive apneas, which increased from 43 to 59 per night. On a separate night, a higher level of CPAP (12.5 cm H2O) resulted in virtually complete removal of all apneas. Measurement of pharyngeal properties revealed pharyngeal cross-sectional area in the low normal range, but increased pharyngeal compliance. This case illustrates that pharyngeal abnormalities may be present in patients with central sleep apnea, and CPAP may be beneficial in the treatment of this disorder. Although the exact mechanism of action of CPAP in this disorder is unclear, we propose several possibilities that may account for the beneficial effect of CPAP in this patient.     

Oral continuous positive airway pressure for sleep apnea: effectiveness, patient preference, and adherence

BACKGROUND: Nasal continuous positive airway pressure (CPAP) is the most definitive medical therapy for obstructive sleep apnea (OSA). Many patients have difficulty tolerating nasal CPAP due to nasal airway problems, mouth leak, and general discomfort from the mask and headgear. These limitations may be overcome by an oral mask (Oracle; Fisher & Paykel Healthcare; Languna Hills, CA) that does not require headgear. We performed a study to compare the Oracle mask to conventional nasal and oronasal masks in the effectiveness of CPAP delivery and patient satisfaction and adherence. METHODS: Ninety-eight, consecutive CPAP-na?ve patients with OSA diagnosed by overnight polysomnography (apnea-hypopnea index [AHI] > 5) were referred for CPAP therapy. All patients were presented with a variety of CPAP masks, including nasal, oronasal, and Oracle, and reasons for mask choice were documented. After 3 weeks of acclimatization to the mask of their choice, patients had a CPAP titration sleep study to determine their optimal CPAP level. Further follow-up was obtained 2 months and 6 months later with a subjective patient assessment of CPAP use and efficacy, mask comfort, and upper airway dryness. RESULTS: Patients were predominantly male (70%), middle aged (50.6 +/- 11.7 years), and moderately obese (body mass index, 32.5 +/- 9.0) with severe OSA (AHI, 40.6 +/- 25.8/h) [mean +/- SD]. Patients were classified into three groups based on their choice of mask: nasal (66%), Oracle (27%), and oronasal (7%). Baseline characteristics did not differ significantly between groups. Optimal CPAP was not significantly different between mask groups (nasal, 7.7 +/- 2.1 cm H(2)O; Oracle, 8.0 +/- 2.0 cm H(2)O; oronasal, 9.7 +/- 3.2 cm H(2)O; p = 0.267). Subjective ratings of adherence, efficacy, and mask comfort were also similar between groups. However, the Oracle group had more complaints of upper airway dryness and "rain-out." The oronasal group had a disproportionately greater number of dropouts from CPAP therapy than the Oracle group (57% vs 19%, p = 0.046). Nine patients changed from the Oracle mask to a nasal mask during the study, whereas no patients changed from their nasal or oronasal masks. CONCLUSIONS: The Oracle mask is an efficacious interface for long-term CPAP therapy in patients with OSA. The main limitations of the mask are upper airway dryness and rain-out associated with heated humidification, which may be improved by further technical modifications. Oracle may be more acceptable than oronasal masks for patients who cannot rely exclusively on the nasal airway for CPAP therapy.     

Long-term adherence to nasal continuous positive airway pressure therapy by hypertensive patients with preexisting sleep apnea

Background and objectiveAlthough positive screening for and treatment of obstructive sleep apnea (OSA) have been recommended for patients with cardiovascular problems, patient adherence to nasal continuous positive airway pressure (CPAP) therapy primarily for a cardiovascular concern is unknown. Therefore, this study aimed to determine the adherence to CPAP therapy by hypertensive patients with OSA after a screening test performed regardless of OSA-related symptoms.Subjects and methodsCPAP therapy was administered to 194 of the 1365 hypertensive patients who underwent the screening. The monthly dropout from CPAP therapy and the adequate use level (4 h every night, 70% days in a month) were assessed using the Kaplan–Meier analysis over a 3-year follow-up period.ResultsOf the patients, 106 (55%) refused or abandoned the therapy by the end of the follow-up period (adherence, 45%). An adequate use level was maintained by 76 patients (39%). Most of the patients’ background characteristics, including age, sex, Epworth sleepiness scale scores, and parameters obtained on polysomnography, were not related to adherence or adequate use level. The good-compliance level on the first visit after CPAP therapy introduction was most strongly related to adherence (95% CI, 0.05–0.32; p < 0.001) and adequate use level (95% CI, 0.06–0.33; p < 0.05). Fourth quartile of apnea hypopnea index value (greater than 67/h) was also related to adherence (95% CI, 0.21–0.98; p < 0.02) and adequate use level (95% CI, 0.19–0.88; p < 0.05).ConclusionsThe adherence and use level in this population may not be satisfactory but are comparable with those in previous sleep center reports treating symptomatic OSA patients. Thus, the present results would encourage hypertensive patients to undergo positive screening for OSA, regardless of OSA-related symptoms. However, an outcomes study with the same cohort is needed.     

Objective adherence to positive airway pressure therapy in an Australian paediatric cohort

Purpose

This study aimed to objectively measure adherence (compliance) and effectiveness of CPAP and BiLevel pressure support in an Australian paediatric population and determine factors associated with adherence outcomes.

Methods

Data was collected as part of routine clinical care from 2011 to 2013. Adherence was recorded by downloads from the PAP device. “Adequate” adherence was defined as ≥4 h/night for 70 % of days used. Effectiveness of therapy was measured by polysomnography (PSG) pre- and post-PAP initiation. One year follow-up was undertaken to determine the long-term utilisation of PAP therapy.

Results

Ninety-nine children were included (55 CPAP, 44 BiLevel). Mean age and BMI z-score were 6.9 ± 5.5 years and 0.1 ± 2.0 for CPAP and 9.8 ± 5.9 years and ?0.5 ± 2.6 for BiLevel, respectively. At initial download, adequate adherence was observed in 75 % of CPAP and 91 % of BiLevel users. Mean hours of use (per night) for all nights used was 6.8 ± 2.8 and 9.3 ± 3.6 h, respectively. PSG demonstrated that CPAP use was associated with >60 % decrease in the obstructive apnoea hypopnoea index (OAHI, 19.0 ± 18.4 to 2.4 ± 3.1; p < 0.001). BiLevel use was associated with improved baseline SaO₂ and TcCO₂ (SaO₂, 92.5 ± 5.4 % to 95.5 ± 2.9 %; p = 0.001 and reduction in TcCO_2, 50.0 ± 10.9 mmHg to 44.8 ± 7.6 mmHg; p = 0.01). At follow-up, 22 (40 %) patients on CPAP and 26 (59 %) on BiLevel continued with therapy, and amongst these, adequate adherence was maintained in 76 % of CPAP and 80 % of Bilevel users.

Conclusions

In this Australian paediatric cohort (predominantly non-obese), adherence with BiLevel was greater than for CPAP. Over half of our population continue to utilise PAP therapy 1 year later, and amongst these cases, adequate adherence was maintained.

     

Long-term acceptance of continuous positive airway pressure in obstructive sleep apnea

We studied the long-term acceptability of nasal continuous positive airway pressure (CPAP) treatment in 168 consecutive patients, 147 with obstructive sleep apnea (OSA) and 21 with snoring. Follow-up was between 1.5 and 78 months. At latest follow-up 107 of 168 (64%) were still using CPAP. Acceptance of CPAP was least for patients with snoring alone (6 of 21 persisted) and best for patients with both excessive daytime somnolence and severe hypoxemia (minimum SaO2 less than 75%), of whom 40 of 45 (89%) persisted with treatment. Patients with excessive daytime somnolence but without severe hypoxemia were less tolerant of CPAP (39 of 71, 55%, persisted) than patients with no symptoms of excessive somnolence but with severe hypoxemia (21 of 30, 70%, persisted). The most common reasons for discontinuing CPAP were intolerance of the mask (26 of 61), the inconvenience of treatment (16 of 61), and the lack of symptomatic benefit from treatment (10 of 61). We concluded that long-term acceptance of CPAP was difficult to predict in advance but that it was most likely in patients with the most severe sleep apnea. Because intolerance of the mask and inconvenience were the most common reasons for ceasing treatment, improvements in the design of CPAP systems and careful patient training may improve the acceptability of CPAP substantially.     

Effectiveness of continuous positive airway pressure in mild sleep apnea-hypopnea syndrome

The aim of this trial was to evaluate the effectiveness of continuous positive airway pressure (CPAP) in patients with mild sleep apnea- hypopnea syndrome (SAHS). One hundred forty-two consecutive patients with mild SAHS (apnea-hypopnea index 10-30, without severe sleepiness) were randomly assigned to receive conservative treatment (CT)-sleep hygiene and weight loss-(65 patients) or CT plus CPAP (77 patients), and 125 patients (86% males, age: 54 +/- 9 yr, BMI: 29 +/- 4 kg/m(2), AHI: 20 +/- 6, ESS: 12 +/- 4) completed the follow-up. The following outcomes were assessed at inclusion and after 3 and 6 mo of treatment: sleepiness (Epworth scale, multiple sleep latency test [MSLT]), other symptoms related to SAHS, cognitive function, and perceived health status (Functional Outcomes of Sleep Questionnaire [FOSQ], Nottingham Health profile). The relief of SAHS-related clinical symptoms was significantly greater in the CPAP group than in the CT group; the Epworth scale and FOSQ also showed more improvement in the CPAP group but did not reach significance. There were no significant differences in the other tests performed probably because the baseline values were normal. CPAP compliance was 4.8 +/- 2.2 h and treatment continuation was accepted by 62% of the patients at the end of the study. These results suggest that CPAP can be considered in treating patients with mild SAHS on the basis of an improvement in symptoms.     

Mouth breathing compromises adherence to nasal continuous positive airway pressure therapy

STUDY OBJECTIVES: Mouth leak compromises nasal continuous positive airway pressure (CPAP) therapy. We hypothesized that patients who breathe mainly through their mouths during sleep, compared to those who breathe mainly through their noses, would have more mouth leak during CPAP and therefore lower adherence to CPAP. DESIGN: A case-control study to compare adherence to CPAP at 1 year in mouth breathers (MBs) with nose breathers (NBs). SETTING: University teaching hospital with a sleep laboratory. PATIENTS: Fifty-one CPAP-naive patients (4 women), with a respiratory disturbance index (RDI) > 15/h. Of the 51 patients, 30 patients breathed through their mouths (mouth breathing > 70% of total sleep time [TST]), and 21 patients breathed through their noses (mouth breathing < 30% of TST). MBs between 30% and 70% of TST were excluded. INTERVENTIONS: Overnight polysomnography was performed at baseline, during CPAP titration, and at 3 months. Patients were followed up for 1 year after beginning CPAP. MEASUREMENTS AND RESULTS: To measure mouth breathing, nasal and oral thermistors during polysomnography were separated by a 3 x 6-cm silicon transverse diaphragm. RDI decreased from (mean +/- SD) 37.8 +/- 21.5 to 1.8 +/- 2.6/h at 3 months. Throughout the study, adherence to CPAP (mean daily CPAP use in hours) was better in NBs. Most NBs (71%) but only 30% of MBs used CPAP daily for > 4 h at 1-year follow-up. Mouth breathing decreased significantly from 84 +/- 8.9% at baseline to 22 +/- 14.4% at 3 months. CONCLUSION: Patients with moderate-to-severe sleep-disordered breathing and a high percentage of mouth breathing during sleep were less adherent to CPAP therapy than patients exhibiting a low percentage of mouth breathing.     

Arbitrary-pressure continuous positive airway pressure for obstructive sleep apnea syndrome

Current resources are inadequate to meet the demand for polysomnography, resulting in long waiting lists. This study aimed to evaluate the role of arbitrary-pressure continuous positive airway pressure (CPAP) as a method to reduce delays in commencing treatment. The study was of an open, randomized, parallel design. Ninety-one subjects with obstructive sleep apnea syndrome were randomized to either arbitrary-pressure CPAP based on body mass index before treatment polysomnography or to CPAP at settings determined by polysomnography. Both interventions resulted in similar improvements in clinical outcomes as determined by Epworth Sleepiness Score, Short Form-36 Quality of Life questionnaire, objective compliance, and subjective attitudes to treatment. There was higher sleep efficiency at treatment polysomnography in the group commenced at arbitrary pressure (81.8 +/- 10.1% [mean +/- SD] compared with 72.2 +/- 18.0%, p = 0.01). Subjects unable to tolerate CPAP were identified by the use of arbitrary pressure, leading to a reduction in the proportion of "wasted" treatment polysomnograms (studies performed in subjects not persisting with treatment) relative to commencing therapy after treatment polysomnography (3 of 39 compared with 12 of 35, p = 0.01). This approach to initiating treatment with CPAP appears feasible when there are long waiting lists for polysomnography.     

Humidified nasal continuous positive airway pressure in obstructive sleep apnoea.

Heated humidification of nasal continuous positive airway pressure (nCPAP) reduces upper airway symptoms and improves initial use in obstructive sleep apnoea syndrome (OSAS). The present study aimed to assess the effect of heated humidification of nCPAP on upper airway symptoms and initial use in obstructive sleep apnoea. This study was of a randomised, crossover design. Subjects with polysomnographically confirmed OSAS were randomised to 3 weeks nCPAP treatment with heated humidification (nCPAP-humid) or placebo humidification (nCPAP pl-humid). Objective and subjective nCPAP use, upper airway symptoms, and treatment satisfaction were compared. Thirty seven of 42 patients completed the protocol. nCPAP-humid reduced the frequency of adverse upper airway symptoms. nCPAP use over 3 weeks was greater with nCPAP-humid compared with nCPAP pl-humid. No difference was found between the treatment arms in terms of subjective treatment satisfaction or alertness. Heated humidification of nasal continuous positive airway pressure reduces upper airway symptoms and is associated with a small increase in initial use but not subjective sleepiness or treatment satisfaction. The results support the use of heated humidification as a strategy to reduce side-effects related to continuous positive airway pressure but not routine initial use.     

Dysfunctional breathing treated with continuous positive airway pressure in newly diagnosed obstructive sleep apnoea: a prospective cohort study

A prospective cohort study investigating patients with obstructive sleep apnoea (OSA) was conducted to determine the prevalence of dysfunctional breathing and if continuous positive airway pressure (CPAP) therapy improves associated symptoms. Almost half of newly diagnosed patients with OSA had dysfunctional breathing and CPAP was not an effective treatment. Dysfunctional breathing is common in patients with OSA.     

The influence of nasal abnormalities in adherence to continuous positive airway pressure device therapy in obstructive sleep apnea patients

Background

The few studies that examine the effect of nasal abnormalities on continuous positive airway pressure device (CPAP) adherence are controversial. The aim of this study was to evaluate the contribution of nasal abnormalities in CPAP adherence.

Methods

We included patients with moderate to severe OSA. The patients were submitted to rhinoscopy, nasofibroscopy, nasal inspiratory peak flow, and acoustic rhinometry. The patients who used a CPAP for 4 h or more per night for at least 70 % of the nights over a 6-month period were considered to have good adherence.

Results

Thirty-four patients finished the study. Eleven (33.4 %) were female and 23 (67.6 %) were male. Sixteen (47.1 %) patients had good adherence. The body mass index (p?=?0.030), neck circumference (p?=?0.006), and apnea–hypopnea index (p?=?0.032) were higher, and the oxyhemoglobin saturation minimum was lower (p?=?0.041) in the good adherence group. Nasal parameters showed no differences between good and poor adherence groups. In Spearman’s correlation, surprisingly, there was a negative correlation between the highest number of hours of CPAP use with smaller values of nasal minimal cross-sectional areas in the supine position (r, 0.375; p?=?0.029). In the linear regression model, the nasal findings that predicted increased of the CPAP use were the following: lower scores of nasal symptoms (p?=?0.007) and lower nasal volume in supine position (p?=?0.001).

Conclusions

The majority of the nasal parameters evaluated in this study did not influence CPAP adherence.     

Influence of continuous positive airway pressure on sleep apnea-related desaturation in sleep apnea patients

To investigate the influence of nasal continuous positive airway pressure (CPAP) on apnea-related desaturation, we compared the sleep apnea-related desaturations obtained during a poly somnographic study before and during nasal CPAP in 15 sleep apnea patients. An individual desaturation curve was determined with a regression analysis by plotting the lowest SaO₂ value reached during each apnea against its duration; these data were collected throughout the night. At baseline, we only considered the apneas with a preapneic SaO₂ value greater than 90% and a minimal SaO₂ value above or equal to 60%. For the CPAP study, the preapneic Sa0₂ value also had to be within 2% the baseline value for the apneas to be retained. Due to the restriction criteria imposed to characterize apnea-related Sa0₂ falls, residual apneas still had to be recorded with CPAP. These data were analyzed separately for obstructive apnea for non-rapid eye movement (REM) and REM sleep stages. A desaturation curve was obtained from 10 sec to a variable upper limit that corresponded to the longest apnea duration commonly reached during both baseline and CPAP for a given apnea-type and sleep stage. The individual apnea-related Sa0₂ fall was characterized by measuring a desaturation area corresponding to the area under the curve. It was expressed in % Sa0₂/sec of apnea. CPAP reduced the number of apneas per hour of sleep from 37.5 ± 6.5 (mean ± SEM) to 14.3 3.7 (p = 0.001), and improved the whole night SaO₂, level as estimated by a cumulative SaO₂ curve. The mean apnea duration was reduced from 22.9 ± 1.5 sec at baseline to 16.8 ± 0.5 sec during CPAP therapy (p = 0.005). The preapneic SaO₂ value was 94.8 ± 0.3% at baseline and 95.5 ± 0.2% during CPAP (p = 0.5). The desaturation area decreased from 267 ± 48% SaO₂/sec at baseline to 152 ± 41% Sa0₂/sec during CPAP (p < 0.001). We conclude that CPAP improves the apnea-related desaturation independently of the shortening of apneas and of any difference in the preapneic SaO₂ value.