Use of conventional and self-adjusting nasal continuous positive airway pressure for treatment of severe obstructive sleep apnea syndrome: a comparative study

Treatment of Obstructive Sleep Apnea: Choosing the Best Positive Airway Pressure Device

Positive airway pressure (PAP) remains primary therapy for most patients with obstructive sleep apnea (OSA). CPAP, APAP, and BPAP are all reasonable therapies that can be used for patients with uncomplicated OSA across the spectrum of disease severity. BPAP should be considered for patients who are nonadherent to CPAP or APAP therapy because of pressure intolerance. Several additional factors should be considered when choosing the type of PAP device for a given patient, including associated symptoms and comorbid medical problems, cost, access to online data management and patient portals, and the portability for the device for patients who travel frequently.

Pressure modification or humidification for improving usage of continuous positive airway pressure machines in adults with obstructive sleep apnoea

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.

Treatment of Adult Obstructive Sleep Apnea With Positive Airway Pressure: An American Academy of Sleep Medicine Systematic Review, Meta-Analysis, and GRADE Assessment

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.

Combination of obstructive sleep apnoea and insomnia treated by continuous positive airway pressure with the SensAwake pressure relief technology to assist sleep: a randomised cross-over trial protocol

INTRODUCTION

Obstructive sleep apnoea (OSA) is a common sleep breathing disorder affecting up to 17% of the middle-aged population. Continuous positive airway pressure (CPAP) is the primary treatment for patients with OSA, but acceptance and adherence to therapy is suboptimal in specific subgroups particularly those with insomnia or poor sleep quality (40%-80% of patients with OSA). Pressure intolerance, particularly during periods of wakefulness, inhibiting sleep onset or return to sleep, is one reason for poor CPAP adherence. AutoCPAPs continually monitor airflow changes and only increase the pressure when the upper airway requires it. Reducing the pressure during wakefulness-sleep transition and wakefulness-after-sleep-onset (WASO) may improve therapy comfort and potentially adherence without compromising therapy efficacy. We hypothesise that SensAwake, a pressure relief function that reduces CPAP pressure on the transition from sleep to wakefulness and on WASO, may improve objective sleep quality.

METHODS AND ANALYSIS

This is a multicentre, randomised double-blind crossover clinical trial on patients with both OSA and insomnia. Insomnia is defined as Insomnia Severity Index >15 at screening. Baseline data, including actigraphy, are collected for 1 week before randomisation (1:1) to either conventional AutoCPAP or AutoCPAP with SensAwake for 4 weeks. After an evaluation visit, patients are switched to the other treatment arm for a further 4 weeks. Allowing for 20% dropout, 48 patients are required. If applicable, repeated measures analysis of variance will be used to assess differences in WASO measured by actigraphy (primary outcome), other actigraphy measures, AutoCPAP compliance, subjective questionnaire scores (Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, Short-Form 12 Health Survey) and 24 hours blood pressure (secondary outcomes).

ETHICS AND DISSEMINATION

The protocol was approved by the regional Ethics Committee (CPP Sud-Est-V, IRB N°6705) on 9 December 2015, is registered on ClincalTrials.gov (NCT02721329) and started in June 2016 with expected publication of primary outcome results in 2018.

TRIAL REGISTRATION NUMBER

NCT0272132; Pre-results.

Treatment of Obstructive Sleep Apnea: Choosing the Best Positive Airway Pressure Device

Positive airway pressure (PAP) remains primary therapy for most patients with obstructive sleep apnea (OSA). CPAP, APAP, and BPAP are all reasonable therapies that can be used for patients with uncomplicated OSA across the spectrum of disease severity. BPAP should be considered for patients who are nonadherent to CPAP or APAP therapy because of pressure intolerance. Several additional factors should be considered when choosing the type of PAP device for a given patient, including associated symptoms and comorbid medical problems, cost, access to online data management and patient portals, and the portability for the device for patients who travel frequently.

Randomised short-term trial of high-span versus low-span APAP for treating sleep apnoea

PURPOSE

Auto-titrating continuous positive airway pressure (APAP) devices were developed to improve treatment efficacy and compliance in patients with obstructive sleep apnoea syndrome (OSAS). Since there are insufficient data on the optimal pressure range setting, we aimed to compare the adherence, efficacy and tolerability of treatment with high-span versus low-span APAP.

METHODS

Seventy-six newly diagnosed OSAS patients fulfilling the treatment criteria were randomised to receive high-span (HS, range 4-15cmH2O, n = 38) or low-span (LS, range 8-12cmH2O, n = 38) APAP. Patients were assessed at 1 and 3 months.

RESULTS

Median Epworth sleepiness scale (ESS) was 13 (IQR, 6-16) and median apnoea-hypopnoea index (AHI) was 35.9 (IQR, 27.6-56.3). There were no significant differences in baseline demographic and clinical characteristics between groups. Overall, no significant differences were found at the first month assessment. After 3 months of therapy, we found again no differences in residual AHI or ESS. However, the group HS proved less adherent than group LS, respectively, with median 87 % (IQR, 60.5-97.5) versus 94 % (IQR, 80.0-98.3) of the nights using ≥4 h (P = 0.014) and mean (±SD) usage 5.7 ± 1.6 versus 6.4 ± 1.2 h/night (P = 0.049). The group HS reported more frequently nasal congestion, excessive oronasal dryness and nocturnal awakenings of at least moderate intensity, the latter with statistical significance (P = 0.005).

CONCLUSIONS

Both pressure ranges appear to be equally effective to correct AHI and to improve symptoms. Though, patients with high-span APAP were less compliant to treatment, raising issues about the tolerability of wide pressure range settings of these devices.

Auto-titrating versus fixed continuous positive airway pressure for the treatment of obstructive sleep apnea: a systematic review with meta-analyses

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Randomised controlled trial of auto-adjusting positive airway pressure in morbidly obese patients requiring high therapeutic pressure delivery

Auto-adjusting positive airway pressure (APAP) devices are being increasingly used to treat obstructive sleep apnoea (OSA). Anecdotal encounters of obese patients requiring high therapeutic pressure whose OSA was inadequately controlled by APAP led to this study aiming to compare the effectiveness of continuous positive airway pressure (CPAP) and APAP (S8 Autoset II(®) , ResMed, NSW, Australia) in a randomised, single-blinded crossover trial. Twelve morbidly obese patients with severe OSA [mean±SD apnoea-hypopnoea index (AHI) 75.8±32.7, body mass index 49.9±5.2 kg m(-2) , mean pressure 16.4 cmH(2)O] were consecutively recruited, and received CPAP or APAP in random order for six nights at home, separated by a four-night washout. Polysomnographic (PSG) indices of OSA were recorded at baseline and following each treatment arm. Both therapies substantially reduced the AHI (APAP 9.8±9.5 and CPAP 7.3±6.6 events h(-1) ; P=0.35), but residual PSG measures of disease (AHI >5) were common. APAP delivered a significantly lower 95th percentile pressure averaged over the home-use arm than CPAP (14.2±2.7 and 16.1±1.8 cmH(2)O, respectively, P=0.02). The machine-scored AHI significantly overestimated the level of residual disease compared with the laboratory-scored AHI (using Chicago criteria); however, when the machine-scored AHI was ≤5 and ≤10 this was always confirmed by the PSG data. In morbidly obese OSA patients without significant co-morbid disease requiring high therapeutic pressure, our data provide support for the use of either APAP or manually titrated CPAP. We recommend objective assessment by sleep study if the S8 Autoset II indicates a high level of residual disease.

Does home sleep testing impair continuous positive airway pressure adherence in patients with obstructive sleep apnea?

BACKGROUND

The increasing recognition of obstructive sleep apnea (OSA) and demand for polysomnography has created a need for home sleep testing (HST) using unattended diagnostic and titration studies. Although these studies increase access to care and reduce cost, the limited interaction with sleep laboratories may negatively affect positive airway pressure (PAP) adherence. We sought to determine the difference in PAP use between HST and traditional in-laboratory studies.

METHODS

This observational cohort study included 210 patients with OSA classified into three equal groups. Following preestablished guidelines, group 1 underwent unattended, type III home diagnostic and unattended home auto-adjustable PAP (APAP) titrations; group 2 underwent in-laboratory, type I diagnostic and continuous PAP titration studies; group 3 underwent type I diagnostic and APAP titration studies. Group 1 was primarily managed and educated in a primary care clinic, whereas groups 2 and 3 received extensive education in an academic sleep medicine center. Objective measures of PAP use during the first 4 to 6 weeks of therapy were compared between groups.

RESULTS

Type of study and location of care did not affect PAP adherence. PAP was used for 70%, 73%, and 72% of nights in groups 1, 2, and 3, respectively (P = .94). Mean hours of nightly use (4.4 ± 2.0 h, 4.7 ± 1.5 h, and 4.6 ± 1.5 h; P = .98) was also similar. Regular use was observed in 54%, 51%, and 50% of subjects (P = .84). Discontinuation rates were similar between groups.

CONCLUSIONS

PAP usage did not differ between those undergoing HST vs in-laboratory studies. HST offers a more accessible and cost-effective alternative without compromising therapeutic adherence.

Treatment of obstructive sleep apnea syndrome

Several treatment options are available for obstructive sleep apnea syndrome (OSAS), including various types of positive airway pressure (PAP) therapy, oral appliances, surgery, and conservative approaches including weight loss and positional therapy. This article focuses on continuous positive airway pressure treatment and technological advancements in the delivery of PAP therapy for OSAS, reviews indications for treatment, treatment outcomes, and methods of improving compliance, and discusses the other non-PAP treatment options.

Pulse wave analysis in a pilot randomised controlled trial of auto-adjusting and continuous positive airway pressure for obstructive sleep apnoea

PURPOSE

Non-invasive measurements of arterial stiffness including the augmentation index (AIx) and central blood pressure (BP) have been used to assess the cardiovascular health of patients with obstructive sleep apnoea (OSA), a well-established independent risk factor of cardiovascular disease. Continuous positive airway pressure (CPAP) can significantly reduce the AIx, but no studies have analysed the effect of auto-adjusting PAP (APAP) or studied morbidly obese patients with severe OSA at higher risk of cardiovascular disease. In this randomised, single-blinded crossover pilot trial, we aimed to compare the efficacy of CPAP with APAP (ResMed S8 Autoset II) in improving peripheral BP, central BP and the AIx, using SphygmoCor technology.

METHODS

Twelve severe OSA patients (mean±SD; apnoea-hypopnoea index, 75.8 ± 32.7; BMI, 49.9 ± 5.2 kg/m(2)) were consecutively recruited and received CPAP (mean pressure, 16.4 cm H(2)O) or APAP in random order for four nights at home, separated by a four-night washout. Cardiovascular measurements were taken at baseline, post-washout and following each treatment arm.

RESULTS

The polysomnographically recorded residual apnoea-hypopnoea index and compliance to treatment were not significantly different between arms (p > 0.05). There were no significant differences in peripheral or central BP between arms (p > 0.05). The AIx was lower with CPAP than APAP (by 5.8%), with a large effect size not reaching statistical significance (r = 0.61, p = 0.14).

CONCLUSION

The large effect size evident when comparing the AIx following CPAP and APAP indicates the need to perform an adequately powered trial in order to determine if APAP improves arterial stiffness to the same extent as CPAP.

Pressure modification for improving usage of continuous positive airway pressure machines in adults with obstructive sleep apnoea

BACKGROUND

Continuous Positive Airways Pressure (CPAP) is considered to be the cornerstone of therapy for obstructive sleep apnoea (OSA). However, compliance with this treatment is frequently poor, which may lead to ongoing symptoms of sleep disruption, daytime sleepiness and poor waking cognitive function. Mechanical interventions which involve changing the way that positive pressure is delivered, and the addition of humidification, might improve compliance.

OBJECTIVES

To determine the efficacy of pressure level modifications and additional humidification in increasing CPAP machine usage.

SEARCH STRATEGY

We searched the Cochrane Airways Group Specialised Register (September 2008).

SELECTION CRITERIA

Randomised controlled trials (RCTs) assessing interventions to improve compliance with CPAP usage. Control groups received fixed pressure CPAP.

DATA COLLECTION AND ANALYSIS

Two authors assessed articles for inclusion in the review and extracted data. We made attempts to obtain additional unpublished data from the trialists.

MAIN RESULTS

Forty-five studies met the inclusion criteria (1874 participants). Auto-CPAP (30 studies, 1136 participants): a statistically significant difference in machine usage of 0.21 hours/night (0.08 to 0.35) was observed in favour of auto-CPAP from cross-over studies. This difference is of questionable clinical significance. Pooled effect estimates from parallel group trials detected a similar sized difference for average nightly machine usage, but this was not statistically significant. Evidence from parallel group studies did not identify a statistically significant difference between pressure modes in Epworth Sleepiness Scores, but there was an overall reduction of 0.64 units with cross-over studies (-0.12 to -1.16) in favour of auto-CPAP. Parallel group studies did not identify a significant difference. More participants preferred auto-CPAP to fixed CPAP where this was measured. Bi-level PAP (six studies, 285 participants): no significant differences were observed in machine usage. One small study found no difference in preference. C-Flex (six studies, 318 participants): no significant difference was observed in machine usage. Humidification (three studies, 135 participants): there were conflicting findings between the studies. Two parallel group trials found no significant difference in machine usage, whereas a cross-over study found a significant difference.

AUTHORS' CONCLUSIONS

Improvement in average machine use of auto-CPAP was superior in studies with a cross-over design; the point estimate in parallel group trials was similar, but did not reach statistical significance. It is uncertain how use of machines in study settings relates to 'real world' use. Where preference was measured participants preferred auto-CPAP to fixed pressure CPAP. Further studies are required to assess the evidence for Bi-PAP, C-Flex(TM) and humidification. The studies assembled were characterised by high machine usage in the control groups, and low withdrawal rates. Future studies need to consider the effects of treatment in participants with more mild disease, and those who struggle to accept therapy despite persistent symptoms.

Reliability of home CPAP titration with different automatic CPAP devices

Background

CPAP titration may be completed by automatic apparatus. However, differences in pressure behaviour could interfere with the reliability of pressure recommendations. Our objective was to compare pressure behaviour and effective pressure recommendations between three Automatic CPAP machines (Autoset Spirit, Remstar Auto, GK 420).

Methods

Sixteen untreated obstructive sleep apnea patients were randomly allocated to one of the 3 tested machines for a one-week home titration trial in a crossover design with a 10 days washout period between trials.

Results

The median pressure value was significantly lower with machine GK 420 (5.9 +/- 1.8 cm H₂O) than with the other devices both after one night and one week of CPAP titration (7.4 +/- 1.3 and 6.6 +/- 1.9 cm H₂O). The maximal pressure obtained over the one-week titration was significantly higher with Remstar Auto (12.6 +/- 2.4 cm H₂O, Mean +/- SD) than with the two other ones (10.9 +/- 1.0 and 11.0 +/- 2.4 cm H₂O). The variance in pressure recommendation significantly differed between the three machines after one night and between Autoset Spirit and the two other machines after 1 week.

Conclusion

Pressure behaviour and pressure recommendation significantly differ between Auto CPAP machines both after one night and one week of home titration.

Nocturnal noninvasive ventilation

Nocturnal noninvasive ventilation (NNV), the provision of ventilatory assistance via a noninvasive interface mainly during sleep, has assumed an important role in the management of chronic hypoventilatory syndromes. This review focuses on recent developments related to the use of NNV to treat various forms of chronic respiratory failure or insufficiency. In the past, NNV has been used mainly to treat respiratory insufficiency in patients with neuromuscular disease (NMD) or chest wall deformity; it should be instituted when these patients have orthopnea or daytime symptoms associated with nocturnal hypoventilation. An emerging application is to treat obesity-hypoventilation syndrome, particularly in continuous positive airway pressure (CPAP) failures. Additionally, it has a role in managing some patients with obstructive sleep apnea who are hypoventilating or find the lower expiratory pressure with bilevel positive pressure ventilators more tolerable than with CPAP alone. NNV to treat severe, stable COPD remains controversial, although a subgroup of patients with hypercapnea and sleep-disordered breathing (SDB) seems most likely to respond favorably. NNV to treat central SDB in patients with congestive heart failure continues to be investigated. Recent findings from a Canadian CPAP trial were disappointing, but preliminary results on a novel adaptive NNV mode are promising.

Sleep apnea: clinical investigations in humans

Sleep apnea syndrome (SAS), a common disorder, is characterized by repetitive episodes of cessation of breathing during sleep, resulting in hypoxemia and sleep disruption. The consequences of the abnormal breathing during sleep include daytime sleepiness, neurocognitive dysfunction, development of cardiovascular disorders, metabolic dysfunction, and impaired quality of life. There are two types of SAS: obstructive sleep apnea syndrome (OSAS) and central sleep apnea syndrome (CSAS). OSAS is a prevalent disorder in which there is snoring, repetitive apneic episodes, and daytime sleepiness. Anatomical conditions causing upper airway obstruction (obesity or craniofacial abnormalities such as retrognathia or micrognathia) can cause OSAS. CSAS, much less common than OSAS, is a disorder characterized by cessation of breathing which is caused by reduced respiratory drive from the central nervous system to the muscles of respiration. The latter condition is common in patients with heart failure and cerebral neurologic diseases. The diagnosis of SAS requires assessment of subjective symptoms and apneic episodes during sleep documented by polysomnography. Treatments of OSAS include continuous positive airway pressure (CPAP), oral appliances, and surgery; patients with CSAS are treated with oxygen, adaptive servo-ventilation, or CPAP. With assessment and treatment of the SAS, patients usually have resolution of their disabling symptoms, subsequently resulting in improved quality of life.

Automatic Pressure Titration with APAP Is as Effective as Manual Titration with CPAP in Patients with Obstructive Sleep Apnea

BACKGROUND

The optimal approach to initiate positive-pressure therapy in patients with obstructive sleep apnea is still debated. Current options are autotitrating positive airway pressure (APAP) or manual titration with continuous positive airway pressure (CPAP). Procedures differ by parameters and by algorithms used for adapting pressure.

OBJECTIVES

To evaluate the efficacy of attended automatic titration in a randomized crossover study compared with manual titration over 2 nights where the sequence of the titration mode was changed. Therapy outcome was controlled after 6 weeks.

METHODS

21 sleep apnea patients were treated using manual CPAP versus automatic APAP titration. The mode used during the 2nd night was continued for 6 weeks. Cardiorespiratory polysomnography, Epworth Sleepiness Scale (ESS), SF-36 score and compliance were assessed.

RESULTS

Apnea-hypopnea index reduction was equally effective at similar effective pressure independent of the titration mode. If APAP was applied during the 1st night, total sleep time was longer (384 vs. 331 min, p < 0.01) and sleep efficacy was higher (91 vs. 81%, p < 0.01) than after starting with manual titration with CPAP. Compliance was comparable in both groups (4.6 +/- 1.9 h). The ESS improved in both groups (from 12.9 to 6.5). SF-36 scores and therapeutic pressure did not much change.

CONCLUSIONS

Taking the sequence of titration into account, we found equal effectiveness of CPAP and APAP. Sleep quality was better with initial application of APAP - which favors attended automatic titration if only 1 titration night is possible. Both modes are comparable after 6 weeks regarding therapeutic pressure, efficacy, compliance and quality of life.

Comparison of Automatic and Continuous Positive Airway Pressure in a Night-by-Night Analysis: A Randomized, Crossover Study

BACKGROUND

Long-term compliance is suboptimal in the treatment of the obstructive sleep apnea syndrome (OSAS).

OBJECTIVES

We compared the efficacy of and the adherence to automatic continuous positive airway pressure (APAP) and constant continuous positive airway pressure (CPAP) based on a night-by-night analysis.

METHODS

We performed a randomized, single-blind crossover study in 20 patients with moderate-to-severe OSAS. After diagnostic polysomnography and manual titration, patients were treated for 8 weeks with both constant CPAP and APAP in random order. Compliance and leakage were analyzed night by night using the software LOGSoft of the Magellan iPAP device.

RESULTS

The reduction in the apnea/hypopnea index (baseline 32.9 +/- 19.1/h, CPAP 4.6 +/- 2.9/h, APAP 5.6 +/- 3.6/h; p < 0.001 compared to baseline) and the Epworth Sleepiness Scale (baseline 10.3 +/- 5.7, CPAP 6.6 +/- 4.8, APAP 4.9 +/- 4.6; p < 0.001 compared to baseline) did not significantly differ between the treatment modes. Leakage time and compliance per night were not statistically different (leakage CPAP 31 +/- 57 min, APAP 25 +/- 49 min; compliance CPAP 383 +/- 116 min, APAP 382 +/- 107 min). There was no correlation between leakage and compliance. Thirteen patients (65%) preferred APAP at the end of the study.

CONCLUSIONS

Treatment efficacy and adherence are similar with CPAP and APAP. There is a trend towards lower leakage with APAP therapy. Patients prefer the automatic mode to fixed pressure.

Pressure-relief continuous positive airway pressure vs constant continuous positive airway pressure: a comparison of efficacy and compliance

OBJECTIVES

To compare polysomnographic data and compliance in sleep apnea patients receiving continuous positive airway pressure (CPAP) and pressure-relief CPAP (PRCPAP) [C-flex; Respironics; Murrysville, PA] as first treatment in the sleep laboratory and subsequently at home.

DESIGN

A prospective, randomized, crossover design was used in the sleep laboratory, and a prospective randomized design was used at home.

PATIENTS

Data were collected from 52 sleep apnea patients for whom CPAP was used for the first time.

INTERVENTIONS

Treatment with constant CPAP and PRCPAP.

MEASUREMENTS AND RESULTS

Patients with a first-time diagnosis of obstructive sleep apnea syndrome (OSAS) underwent conventional CPAP titration. Thereafter, polysomnography was performed at the titrated pressure using both the fixed CPAP pressure mode and the PRCPAP mode in a randomized crossover approach. The patients were then discharged home for 7 weeks of treatment with the last-applied treatment mode, and compliance data were established at the end of that time. The average apnea-hypopnea index was 53.3/h in the "diagnostic night," 5.8/h with CPAP, and 7.0/h with PRCPAP. The native arousal index was 35.2/h, 12.6/h with CPAP, and 12.9/h with PRCPAP (not significant [NS]). The central apnea index was 0.7/h with CPAP and 1.2/h with PRCPAP (p < 0.05). Compliance after 7 weeks was, on average, 9.4 min longer with PRCPAP than with CPAP (NS). Evaluation of a 13-item questionnaire showed scores of 16.4 for PRCPAP and 18.1 for constant CPAP (NS) [the fewer the complaints, the lower the score]. With regard to oral dryness, the score with PRCPAP (1.4) was significantly lower than with constant CPAP (1.9) [p < 0.05]. This difference was no longer detectable after 7 weeks.

CONCLUSION

In terms of the effectiveness in treating obstructive sleep apnea, PRCPAP and constant CPAP are comparable. During the first night of treatment, patients receiving PRCPAP had less dryness of mouth; over a period of 7 weeks, this difference disappeared. Nightly use of the device was comparable in both groups. PRCPAP is therefore a new ventilation mode that enables effective treatment of OSAS patients. Further studies should be done to investigate the effects of expiratory pressure lowering in low-compliance patients and patients requiring CPAP > 9 cm H(2)O or experiencing dry mouth with CPAP.

Obstructive sleep apnea - management update

Obstructive sleep apnea (OSA) is a highly significant condition based both on the high prevalence in community and significant consequences. Obstructive sleep apnea syndrome (OSAS), OSA together with hypersomnolence, is seen in 4% of middle-aged men and 2% of middle-aged women. OSA is associated with impaired quality of life and increased risks of motor vehicle accidents, cardiovascular disease (including hypertension and coronary artery disease), and metabolic syndrome. There is some evidence for the use of conservative interventions such as weight loss and position modification. CPAP remains the mainstay of treatment in this condition with high-level evidence supporting its efficacy. Continuous positive airway pressure (CPAP) is an intrusive therapy, with long-term adherence rates of less than 70%. Dental appliances have been shown to be effective therapy in some subjects but are limited by the inability to predict treatment responders. Alternative treatments are discussed but there is little role for upper airway surgery (except in a select few experienced institutions) or pharmacological treatment. The current levels of evidence for the different treatment regimens are reviewed.

Simple interventions improve re-attendance when treating the sleep apnoea syndrome

BACKGROUND AND PURPOSE

Interventions to improve treatment outcomes in sleep apnoea-hypopnoea syndrome (SAHS) have had mixed success. Most have concentrated on following the use of a continuous positive airway pressure (CPAP) machines; poorer users may not return for machine readings, so any compliance study must take into account rates of attendance rates. We hypothesised that a series of additional, early support measures would improve re-attendance over a sustained period.

PATIENTS AND METHODS

Prospective, single-blinded interventional study. Seventy-two consecutive patients starting CPAP for SAHS were randomised to receive standard follow-up or extra early support. Attendance rates, CPAP use, Epworth scores, side-effects scores and number of changes to equipment were compared, by intent to treat, in both groups at 1 and 12 months.

RESULTS

Re-attendance rates were higher in the intervention group at 1 month (P=0.04), 6 months (P=0.07) and 12 months (P=0.12). Those who defaulted tended previously to be poor users of the CPAP machine. For those who re-attended there was no difference in machine use or other outcomes.

CONCLUSIONS

Simple interventions while commencing CPAP improve re-attendance with maximal benefit early on. This could provide more opportunities for solving problems early or considering alternative treatments. By confirming that poorer CPAP users eventually have higher default rates we recommend that future studies on CPAP compliance should first account for re-attendance rates.

Equivalence of Autoadjusted and Constant Continuous Positive Airway Pressure in Home Treatment of Sleep Apnea

Whether computerized autoadjusted continuous positive airway pressure (aCPAP) is effective or even superior to constant continuous positive airway pressure (cCPAP) in the treatment of obstructive sleep apnea syndrome (OSAS) is still controversial. We performed a randomized, double-blind, controlled, cross-over trial comparing efficacy of sleep apnea home therapy by a novel aCPAP machine (REMStarAuto; Respironics; Murrysville, PA) operated in autoadjusted or constant mode. Thirty sleep apnea patients were recruited consecutively. Mean baseline Epworth sleepiness scale (ESS) score was 12.7 +/- 0.6 (+/- SD), mean sleep resistance time was 26 +/- 2 min (Osler test; Stowood Scientific Systems; Oxford, UK), and mean apnea-hypopnea index (AHI) was 41.1 +/- 3.6 h. Patients were randomly assigned to 1 month of home therapy with aCPAP followed by 1 month with cCPAP, or vice versa. After 1 month with treatment, the mean ESS score, sleep resistance time, and AHI were significantly improved (6.6 +/- 0.6, 37 +/- 1 min, and 4.6 +/- 0.7 h, respectively; all p < 0.05 vs baseline). Similar effects were achieved with cCPAP (p = not significant vs aCPAP). Twenty-six patients preferred aCPAP, and 4 patients preferred cCPAP (p < 0.001). We conclude that patients with OSAS preferred aCPAP over cCPAP in the initial phase of therapy. The effectiveness aCPAP in improving major outcomes was equivalent to cCPAP. Since aCPAP does not require initial titration, it is a simple and promising modality for sleep apnea home therapy.

Comparison of three ways to determine and deliver pressure during nasal CPAP therapy for obstructive sleep apnoea

BACKGROUND

The simplest method of initiating and maintaining therapeutic continuous positive airways pressure (CPAP) therapy for obstructive sleep apnoea (OSA) has not been established.

METHODS

Ninety eight subjects with OSA requiring CPAP treatment (more than 10 dips in oxygen desaturation of >4% per hour of sleep study and Epworth Sleepiness Score (ESS) >9) were randomised prospectively to three different methods of CPAP delivery for 6 months: (1) autotitration pressure throughout; (2) autotitration pressure for 1 week followed by fixed pressure (95th centile) thereafter; and (3) fixed pressure determined by algorithm (based on neck size and dip rate). Patients and investigators were blind to group allocation. One week after initiation the patients were routinely reviewed by sleep nurses. Study assessments took place before starting CPAP treatment and 1 and 6 months after to assess ESS, maintenance of wakefulness test, 24 hour blood pressure, general health (SF-36), and sleep apnoea related quality of life. CPAP internal monitoring data were also collected.

RESULTS

There were no significant differences in any of the outcome measures or CPAP monitoring data between the three groups. The 95th centile CPAP pressures delivered in the 6 month and 1 week autotitration groups were higher than in the algorithm group, but the median pressures were lowest in the 6 month autotitration group.

CONCLUSIONS

The method of determining CPAP pressure for treatment of moderate to severe OSA makes no significant difference to clinical outcome measures. The autotitration CPAP machine used has no advantage in this setting over simpler methods of pressure determination.

Nap-titration: an effective alternative for continuous positive airway pressure titration

When treating Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) several alternatives for standard (manual) continuous positive airway pressure (CPAP) titration are feasible. A practical alternative is titration without polysomnography during an afternoon nap (Nap-titration). The aim of the present study was to assess whether Nap-titration is appropriate for effective titration of CPAP. Following Nap-titration 24 eligible OSAHS patients started conventional CPAP therapy. The outcome of Nap-titration was verified after 2 weeks with CPAP pressure adjustments being performed in case of persisting OSAHS symptomatology. Polysomnography and a questionnaire evaluation were performed at baseline and 8 weeks after Nap-titration. Following Nap-titration 15 patients did not require pressure changes while in 9 patients' CPAP pressure was raised due to persisting OSAHS symptomatology. Control polysomnography after 8 weeks showed successful CPAP titration (Apnea-Hypopnea Index <5) in 23 out of 24 patients. A pressure raise following polysomnography was indicated in 1 patient only. In addition, significant improvements were found in OSAHS symptomatology and quality of life. This study shows that in 96% of OSAHS patients' successful CPAP titration is attained following Nap-titration whether or not supplemented by pressure adjustments. Therefore, Nap-titration with an adequate follow-up appears an appropriate procedure for the effective titration of CPAP.

Treatment adherence and outcomes in flexible vs standard continuous positive airway pressure therapy

STUDY OBJECTIVES

To compare adherence and clinical outcomes between flexible positive airway pressure (PAP) [C-Flex; Respironics; Murraysville, PA] and standard PAP therapy (ie, continuous positive airway pressure [CPAP]).

DESIGN AND SETTING

A controlled clinical trial of CPAP therapy vs therapy using the C-Flex device in participants with moderate-to-severe obstructive sleep apnea. Participants were recruited from and followed up through an academic sleep disorders center.

PARTICIPANTS

Eighty-nine participants were recruited into the study after they had undergone complete in-laboratory polysomnography and before initiating therapy. Participants received either therapy with CPAP (n = 41) or with the C-Flex device (n = 48), depending on the available treatment at the time of recruitment, with those recruited earlier receiving CPAP therapy and those recruited later receiving therapy with the C-Flex device. Follow-up assessments were conducted at 3 months.

MEASUREMENTS AND RESULTS

The groups were similar demographically. The mean (+/- SD) treatment adherence over the 3-month follow-up period was higher in the C-Flex group compared to the CPAP group (weeks 2 to 4, 4.2 +/- 2.4 vs 3.5 +/- 2.8, respectively; weeks 9 to 12, 4.8 +/- 2.4 vs 3.1 +/- 2.8, respectively). Clinical outcomes and attitudes toward treatment (self-efficacy) were also measured. Change in subjective sleepiness and functional outcomes associated with sleep did not improve more in one group over the other. Self-efficacy showed a trend toward being higher at the follow-up in those patients who had been treated with the C-Flex device compared to CPAP treatment.

CONCLUSIONS

Therapy with the C-Flex device may improve overall adherence over 3 months compared to standard therapy with CPAP. Clinical outcomes do not improve consistently, but C-Flex users may be more confident about their ability to adhere to treatment. Randomized clinical trials are needed to replicate these findings.

Sleep.7: positive airway pressure therapy for obstructive sleep apnoea/hypopnoea syndrome

The use of continuous positive airway pressure (CPAP) in treating symptoms associated with OSAHS is reviewed. Although it is an imperfect intervention, it continues to evolve and improve in such a way that patients who would not have been able to use this treatment even in the recent past can benefit from it today.

Interventions to improve compliance with continuous positive airway pressure for obstructive sleep apnoea

BACKGROUND

Continuous Positive Airways Pressure (CPAP) is currently considered to be the cornerstone of therapy for sleep apnoea (OSA). However compliance with this treatment is frequently poor, which may lead to ongoing symptoms of sleep disruption, daytime sleepiness and poor waking cognitive function. Mechanical and psychological/educational interventions have been proposed to try to increase the hours of use of CPAP therapy.

OBJECTIVES

To determine the efficacy of interventions designed to increase compliance with CPAP.

SEARCH STRATEGY

We searched the Cochrane Airways Group Sleep Apnoea Specialised Register (January 2004).

SELECTION CRITERIA

Randomised controlled trials (RCTs) assessing interventions to improve compliance with CPAP usage were considered for inclusion in the review.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed articles for inclusion in the review and extracted data. Attempts were made to obtain additional unpublished data from the trialists.

MAIN RESULTS

24 studies met the inclusion criteria with 1007 participants. Each of the mechanical interventions was compared with fixed CPAP alone. Auto-CPAP (13 studies): A small, significant difference was observed in compliance but this effect disappeared when we took account of the variation between the studies. There may be a subgroup of patients who respond better than others. Most participants preferred auto-CPAP to fixed CPAP where this was measured. Bi-level PAP (3 studies): No significant differences were observed in compliance. One small study found no difference in preference. Patient titrated CPAP (1 study): No significant difference was observed in compliance. Humidification(1 study): This small study found no significant difference in compliance. Educational/psychological interventions (6 studies): One small study demonstrated superior compliance in patients treated with cognitive behavioural therapy + CPAP versus CPAP alone but only after 12 weeks. In one, larger study intensive support including home visits increased hours of use. No other study demonstrated significant effects in favour of active treatment.

REVIEWERS' CONCLUSIONS

The effect of Auto-CPAP in increasing hours of use in unselected patients starting this treatment remains unclear. Different pooled analyses gave conflicting results and it may be that carefully selected participants may respond more favourably than others. The evidence in support of Bi-PAP, self-titration and humidification is lacking and studies are required in these areas. There is some evidence that psychological/educational interventions improve CPAP usage. This requires confirmation in larger studies of longer duration, with rigorous follow-up. The cost-benefit ratio of such interventions requires assessment. Future studies need to consider the effects of treatment in participants who are poorly compliant. The studies assembled were characterised by high machine usage in the control groups, and low withdrawal rates making it less likely that any benefit could be demonstrated.

CPAP compliance in sleep apnea patients with and without laboratory CPAP titration

Advances in auto-adjusting positive airway pressure technology for obstructive sleep apnea now permit this treatment to be initiated outside of the sleep laboratory environment, bypassing the need for laboratory-based titration studies. Thus far, little research has addressed how such developments may affect compliance to continuous positive airway pressure (CPAP). We tested the effect of laboratory CPAP exposure and technologist support in a retrospective chart review of 98 veterans with obstructive sleep apnea to determine whether patients who received standard laboratory CPAP titration complied better with CPAP than did patients who received no laboratory CPAP titration. Fifty patients underwent standard technician-attended polysomnography (PSG) with CPAP titration, and 48 patients underwent unattended PSG with no laboratory trial of CPAP (first CPAP exposure was at home). Objective CPAP compliance measures were obtained from CPAP units at follow-up visits. Attended-PSG patients wore CPAP significantly longer per night on average (5.0 hours vs 3.9 hours) and tended to wear CPAP on more nights (76.5% vs 64.2%) compared with unattended-PSG patients. These findings suggest that patients' sleep laboratory experience with CPAP and the support and education provided by sleep technologists are important factors in facilitating CPAP compliance.

Constant vs Auto-Continuous Positive Airway Pressure in Patients With Sleep Apnea Hypopnea Syndrome and a High Variability in Pressure Requirement

STUDY OBJECTIVES

Auto-continuous positive airway pressure (CPAP) has been reported to have no more efficacy than constant CPAP in unselected patients with sleep apnea hypopnea syndrome (SAHS). The aim of this study was to evaluate patients judged to be good candidates for auto-CPAP because of a high within-night variability in pressure requirement.

DESIGN

Single-blind, randomized, cross-over study (2 x 8 weeks) to compare auto-CPAP with constant CPAP.

PATIENTS

Outpatients with moderate-to-severe SAHS attending the chest clinic.

INTERVENTIONS

Patients were equipped at home in the auto-CPAP mode (model GK418A; Malinckrodt; Nancy, France), using a 4- to 14-cm H(2)O pressure range. Those individuals having a high within-night variability in pressure requirement, assessed at the end of a 14-day run-in period, were included in the cross-over study. Auto-CPAP was compared with constant CPAP (according to a titration night in the sleep laboratory) in terms of compliance, efficacy on apneas (assessed from the pressure monitor), and sleepiness (assessed on the Epworth sleepiness scale).

MEASUREMENTS AND RESULTS

Of 90 consecutive patients with SAHS, 27 patients were selected for a within-night variability in pressure requirement exceeding a given threshold. After completion of the cross-over, 24 patients were evaluable. The median percentage of nights the machine was used was 95.5% (range, 45 to 100%) on constant CPAP, and 96.5% (range, 40 to 100%) on auto-CPAP; the median apnea index recorded by the device was 0.40/h (range, 0 to 2.40/h) on constant CPAP, and 0.45/h (range, 0 to 5.80/h) on auto-CPAP (differences not significant). The mean Epworth sleepiness score was significantly (p < 0.01) lower on auto-CPAP (5.1; SD, 2.8) than on constant CPAP (6.1; SD, 2.8).

CONCLUSIONS

In patients selected for a high within-night variability in pressure requirement, auto-CPAP administered via a GK418A device was equivalent to constant CPAP based on a titration night in the sleep laboratory. Subjective ratings for sleepiness were slightly lower on auto-CPAP.

Randomized Short-term Trial of Two AutoCPAP Devices versus Fixed Continuous Positive Airway Pressure for the Treatment of Sleep Apnea

We evaluated the efficacy of two different continuous positive airway pressure devices with automatic mask pressure adjustment (autoCPAP) in comparison with fixed CPAP in treating obstructive sleep apnea syndrome in 29 patients. The mean (+/- SE) apnea-hypopnea index was 46 +/- 4 per hour and the Epworth score was 14.2 +/- 0.7. Patients were treated over three consecutive 1-month periods with three regimens in random order: an autoCPAP device responding to apnea-hypopnea and snoring, another autoCPAP device responding to snoring and changes in flow contour, and fixed CPAP at the 90th pressure percentile titrated by autoCPAP over 2 weeks. Allowed pressure in the autoCPAP mode was 4 to 15 cm H2O. At the end of each treatment period, symptoms, quality of life, vigilance, and nocturnal breathing disturbances were evaluated. All three treatment modalities improved symptoms, quality-of-life domains, and apnea-hypopnea index significantly and to a similar degree. Mean (+/- SE) maintenance-of-wakefulness time increased by 4.5 +/- 1.8, 6.0 +/- 1.5, and 6.1 +/- 1.4 minutes with DeVilbiss AutoAdjust LT, AutoSet T, and fixed-pressure CPAP, respectively (p<0.001 vs. baseline, p=not significant for comparisons among the three modalities). We conclude that both autoCPAP devices were equally effective as fixed-pressure CPAP in improving major outcomes during short-term therapy of sleep apnea.

Continuous positive airway pressure: new generations

Automatic positive airway pressure devices are the most technologically advanced positive airway pressure devices available for use in OSA. Although heterogeneous, they have in common the ability to detect and respond to changes in upper airway resistance. Data cannot necessarily be extrapolated from one device to another, and the field is rapidly advancing. Most studies of APAP have been performed in a supervised setting, or patients have been carefully selected to have a high likelihood of OSA uncomplicated by disorders such as alveolar hypoventilation or central apnea or technical problems such as mask leaks. Studies of APAP for the diagnosis of OSA have shown that APAP can diagnose severe OSA effectively, but the diagnosis of mild-moderate OSA is less reliable. APAP devices also can be effective therapy for selected patients with OSA, with overall similar results to conventional fixed CPAP in terms of respiratory disturbances, sleep quality, nocturnal oxygenation, and daytime sleepiness and performance, with less known or other long-term outcomes. In most studies, mean treatment pressures are lower, without change in side effect profile. Compliance and preference with APAP are similar to or somewhat better than CPAP in most studies. APAP also can be used in an attended setting to titrate an effective pressure for use in long-term conventional CPAP therapy, also with similar results to CPAP in many patients. APAP devices are more expensive than CPAP devices, but the cost may be outweighed if a group of patients who can be diagnosed, treated, or titrated safely in the unattended setting can be identified. Although diagnostic and therapeutic algorithms for APAP have been proposed, the best candidates for this modality must be defined better.

Improving CPAP use by patients with the sleep apnoea/hypopnoea syndrome (SAHS)

Though continuous positive airway pressure (CPAP) is the treatment of choice for the sleep apnoea/hypopnoea syndrome (SAHS), suboptimal adherence to CPAP is common. Internationally, some 5-50% of SAHS patients recommended for CPAP either reject this treatment option or discontinue within the first week, and 12-25% of remaining patients can be expected to have discontinued CPAP by 3 years. Biomedical investigations of patients' CPAP use reveal frequent adverse effects, weak prospective relationships between symptomatic or physiological disease severity and CPAP use, and moderate correlations between use and benefit. Relatively expensive high-technological interventions to improve CPAP use (e.g. "intelligent" CPAP, humidification) are the subject of several well-conducted studies favouring their effectiveness. More basic educational and behavioural supports, and low-technological interventions (e.g. chinstraps, mask re-fitting) appear valued, but are currently less rigorously evaluated. In other diseases with demanding treatment regimens, cognitive constructs including health attitudes and beliefs (health value, locus of control, chance, powerful others, self-efficacy) and mental and physical health status are significant predictors of adherence. The enhancement of multidisciplinary models with psychosocial interpretations may provide increased explanatory and interventional potential in models of CPAP use. While acknowledging the scarcity of evidence, a structured, multidisciplinary, cost-efficient model is suggested, containing educational, behavioural and technological components as basic support, and with high-expertise cognitive-behavioural intervention in more difficult cases of low CPAP use.

Comparison between automatic and fixed positive airway pressure therapy in the home

We tested the hypothesis that continuous positive airway pressure (CPAP) use and outcomes can be improved by an autotitrating CPAP device in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) who require higher CPAP (10 cm H2O or more). In this multisite randomized single-blind cross-over study, 44 patients (mean age, 49 +/- 10 years) were randomized to 6 weeks at laboratory-determined fixed pressure and 6 weeks on autotitrating CPAP. Average nightly use was greater in automatic mode (306 versus 271 minutes, p = 0.005); median and 95th centile pressures in automatic mode were lower (p < 0.002). Automatic CPAP resulted in better SF-36 Vitality scores (65 +/- 20 versus 58 +/- 23, p < 0.05) and mental health scores (80 +/- 14 versus 75 +/- 18, p < 0.05), but no significant difference in Epworth score (p = 0.065). During automatic therapy, patients reported more restful sleep, better quality sleep, less discomfort from pressure, and less trouble getting to sleep for both the first week of therapy and for the averaged scores for Weeks 2-6 (all p values < 0.006). Patients who require higher fixed CPAP use autotitrating CPAP more and report greater benefit from this therapy.

Sleep structure correlates of continuous positive airway pressure variations during application of an autotitrating continuous positive airway pressure machine in patients with obstructive sleep apnea syndrome

STUDY OBJECTIVES

To evaluate the relationship between sleep structure and continuous positive airway pressure (CPAP) delivered by an automatic CPAP (auto-CPAP) machine in patients with obstructive sleep apnea syndrome (OSAS).

DESIGN

Nocturnal polysomnography was performed during CPAP administration by an auto-CPAP machine (Autoset Clinical 1; ResMed; Sydney, Australia).

SETTING

Sleep-disorders center in a research institute.

PATIENTS

Fifteen subjects with newly diagnosed OSAS deserving home CPAP treatment.

MEASUREMENTS AND RESULTS

During the night, in most cases, the lowest CPAP level was recorded during a prolonged nonrapid eye movement (NREM) sleep period uninterrupted by arousals, whereas the highest level during wake-sleep transitions or NREM sleep fragmented by arousals. In four subjects, rapid eye movement sleep was always associated with increasing CPAP. Sleep efficiency was negatively correlated with CPAP variability, evaluated as the SD of the mean nocturnal CPAP level averaged epoch by epoch (r = 0.63, p < 0.02). Eighty-eight percent of rapid CPAP augmentations (increases by at least 2 cm H(2)O in less-than-or-equal 2 min) were observed during sleep-wake transitions or after arousals/awakenings (Ar/Aw); 63% of such Ar/Aw were not preceded by any detectable respiratory abnormality.

CONCLUSIONS

CPAP levels and variations during auto-CPAP application may be mainly related to sleep continuity and efficiency. The recording of a highly variable pressure during auto-CPAP administration in an unattended environment must raise the question whether the patient's sleep quality was acceptable. A poor sleep quality during an autotitration night could lead to an undesirable overestimation of the CPAP level needed for use with fixed-level CPAP machines.

Compliance with continuous positive airway pressure therapy: assessing and improving treatment outcomes

Although nasal continuous positive airway pressure (CPAP) is generally effective in correcting sleep-related respiratory disturbance and associated daytime sequelae in obstructive sleep apnea syndrome (OSAS), resistance to and intolerance of CPAP poses a serious limitation to its use. Failure to comply with treatment has been reported to be as high as 25 to 50%, with patients typically abandoning therapy during the first 2 to 4 weeks of treatment. Reasons for discontinuing CPAP therapy have been primarily related to issues of mask discomfort, nasal dryness and congestion, and difficulty adapting to the pressure. Although there has been great variability in the reported rates of CPAP compliance, there have been few systematic studies to evaluate barriers to CPAP compliance or ways to improve compliance. Early identification of CPAP-related tolerance problems or barriers, psychological factors, and the predictive value of pretreatment background variables ( ie, age and gender) may enhance compliance with therapy. An important goal for OSAS management is the development of intervention strategies and educational approaches that minimize side effects and maximize patient compliance. A new classification is presented, along with suggestions and ideas for intervention.

Effect of continuous positive airway pressure on sleep architecture in the sleep apnea-hypopnea syndrome: a randomized controlled trial

There is randomized controlled evidence that patients with sleep apnea-hypopnea syndrome (SAHS) treated with continuous positive airway pressure (CPAP) have improved daytime function and quality of life. "Before-and-after" data indicate that CPAP improves sleep quality, but there is no randomized controlled evidence of this. We tested the hypothesis that CPAP improved sleep quality in patients with SAHS. We also sought correlations between polysomnographic (PSG) indices and benefit from use of CPAP. Twenty-two patients with SAHS (median, [interquartile range] apnea-hypopnea index, 40 [25-65] events/h) spent 1 mo receiving CPAP and 1 mo receiving placebo capsules, in random order, and home sleep studies were performed at the end of each month. CPAP resulted in a lower arousal index, less Stage 1, and more Stage 3+4 sleep, but there was no increase in Stage REM (rapid eye movement) sleep. Improvement in Epworth score after 6-12 mo of treatment correlated significantly with PSG indices on CPAP: sleep efficiency index (r = 0.78, p < 0.001), Stage REM (r = 0.55, p = 0.001), Stage 3+4 (r = 0.5, p = 0.02), and arousal index (r = -0.43, p = 0.05). This study provides randomized controlled trial evidence that patients with SAHS sleep better when receiving CPAP. Patients with good sleep quality on CPAP at 1 mo are likely to gain later benefit in subjective daytime sleepiness.

Pulmonary complications of obesity

Obesity can profoundly alter pulmonary function and diminish exercise capacity by its adverse effects on respiratory mechanics, resistance within the respiratory system, respiratory muscle function, lung volumes, work and energy cost of breathing, control of breathing, and gas exchange. Weight loss can reverse many of the alterations of pulmonary function produced by obesity. Obesity places the patient at risk of aspiration pneumonia, pulmonary thromboembolism, and respiratory failure. It is the most common precipitating factor for obstructive sleep apnea and is a requirement for the obesity hypoventilation syndrome, both of which are associated with substantial morbidity and increased mortality. There are numerous medical and surgical therapies for obstructive sleep apnea and obesity hypoventilation. Weight reduction in the obese is among the most effective of these measures.

Autoadjusting CPAP therapy based on impedance efficacy, compliance and acceptance

Constant continuous positive airway pressure (CPAP) is the treatment of choice for the obstructive sleep apnea syndrome (OSAS). To enable the pressure to be matched more accurately to actual requirements, and thus increase patient acceptance, an autoadjusting device based on the measurement of upper airway impedance was developed (APAP(FOT)). We investigated the efficacy and compliance in continuous use at home. Fifty-two patients were treated (randomized crossover) with CPAP and APAP(FOT) for 6 wk each. Respiratory disturbances, sleep profile, and arousals improved significantly with both modes (AHI: baseline, 35.1 +/- 26/h; APAP(FOT), 5.0 +/- 5.2; CPAP, 4.3 +/- 6.3; p < 0.001 baseline versus each mode). The mean pressure with APAP(FOT) was significantly reduced as compared with CPAP (CPAP, 7.8 +/- 1.5 cm H2O; APAP(FOT), 5.7 +/- 1.8 cm H2O; p < 0.001). Under APAP(FOT) the pressure was lower than that under CPAP for 81.5 +/- 21% of the time. Although overall use did not differ, 75% of the patients preferred APAP(FOT) for home treatment. We conclude that APAP(FOT) is as efficacious as constant CPAP in the treatment of OSAS. The treatment pressure can be reduced significantly, and sleep microstructure improved with APAP(FOT). These might be the reasons for patient preference of automatic therapy.