Continuous positive airway pressure (CPAP) has become the treatment of choice for obstructive sleep apnea syndrome. Successful therapy with CPAP depends greatly on individual patient acceptance and compliance. Current indications for CPAP, including those for mild obstructive sleep apnea, will need to be revisited when results from the longitudinal follow-up of the Wisconsin Cohort and the Sleep Heart Health Study are made available.
Obstructive sleep apnea (OSA) syndrome (OSAS) is a major public health problem with a high prevalence in adult men and women, 2% and 4%, respectively . It is characterized by repetitive closure of the upper airway during sleep resulting in cyclical oxygen desaturations and arousals with subsequent long-term adverse health consequences . Continuous positive airway pressure (CPAP) has become the treatment of choice since its introduction in 1981 . A CPAP unit consists of a blower that generates positive pressure, which is then delivered by way of a hose through an appropriate interface to the patient. It functions as a pneumatic splint thereby preventing the upper airway from collapsing cyclically during sleep in OSA. Continuous positive airway pressure is now considered the standard of treatment for OSAS . Although several studies have demonstrated the usefulness of CPAP for treating OSAS, problems with appropriate patient–CPAP interface and inadequate adherence often limit its efficacy.
Indications for continuous positive airway pressure therapy in obstructive sleep apnea
Available evidence supports the use of CPAP for patients who have moderate to severe OSA with respiratory disturbance index (RDI) 15/h or more. RDI is defined as the number of respiratory events, including apneas, hypopneas, and respiratory effort–related arousals per hour of sleep . The term RDI is used interchangeably with apnea hypopnea index (AHI) in this article. By consensus , mild sleep apnea is AHI greater than 5 and 15 or fewer episodes per hour; moderate sleep apnea, AHI greater than 15 and 30 or fewer episodes per hour; and severe sleep apnea, AHI greater than 30 episodes per hour of sleep. CPAP probably functions by splinting the upper airway open by raising the intraluminal upper airway pressure above the positive critical transmural pressure of the upper airway and increasing lung volume . In addition to acting as a splint for the collapsible upper airway tube and hence improving nocturnal oxygenation, CPAP possibly also works by increasing the awake ventilatory drive and the airway tone . CPAP eliminates both obstructive and mixed apneas . Patients who have moderate to severe OSA should be treated with CPAP . In addition to moderate and severe OSA, patients who have mild OSA in the presence of comorbid factors (eg, symptoms of daytime sleepiness, impaired cognition, mood disorders, or documented cardiovascular diseases) experience benefit from CPAP therapy . Evidence from large epidemiologic studies, including the Wisconsin Sleep Cohort and the Sleep Heart Health Study (SHHS) , demonstrated increased risk for hypertension (HTN) even with a mild degree of OSA. The use of CPAP in patients who have mild OSA who do not have associated symptoms of sleepiness, cognitive dysfunction, or underlying cardiovascular diseases is controversial. Many patients who have a mild degree of abnormality do not have subjective symptoms of sleepiness. In fact, some individuals who have mild sleep apnea may have complaints of insomnia or may present with neuropsychologic deficits that are evident only on objective testing that may also warrant therapy with CPAP. Additionally, the risk for motor vehicle accidents correlates much more highly with AHI than measures of sleepiness, with evidence of a marked increased risk even in moderate OSA . Studies have also shown that CPAP objectively improves neuropsychologic functioning even in mild OSA . In addition, we now know from the Wisconsin Sleep Cohort and the SHHS that even AHI as low as 5/h in asymptomatic subjects poses a risk for HTN, ischemic heart disease, stroke, and other cardiovascular diseases . In the SHHS, however, there was no evidence of a dose–response relation between the AHI and cognitive function between subjects who had mild to moderate levels of OSA . Controlled outcome studies demonstrating reversal of cardiovascular morbidity and mortality are few in the mild OSA group. Longitudinal studies are needed to evaluate these concerns.
Initiation of continuous positive airway pressure
Following a diagnostic nocturnal polysomnography or following the diagnostic portion of a split-night study, patients who meet diagnostic criteria for OSA and who opt for CPAP undergo CPAP titration in the sleep laboratory . This titration is done while monitoring electroencephalography, electrooculography, oronasal airflow, chest wall effort, body position, snoring microphone, electrocardiogram, and oximetry. The patient is initially educated about the indications for CPAP and is allowed to adapt to the equipment and different masks. An initial short period of desensitization before the study is recommended, which allows the patient to get accustomed to the idea of wearing the equipment through the night. An attended study is most accurate and allows for technologist intervention for mask leaks, lost leads, and adjustment of CPAP according to body positions and rapid eye movement (REM) sleep . No precise protocol for CPAP titration exists, but general recommendations have been established. Usually, one starts at a low pressure of 4 to 5 cm, gradually increasing by 1 to 2 cm every 15 to 20 minutes until the apneas, hypopneas, respiratory effort–related arousals, and snoring are abolished. Patients who hypoventilate or who have other comorbidities (eg, chronic obstructive pulmonary disease, congestive heart failure (CHF), neuromuscular disease) may require in-line oxygen to correct hypoxia, but generally only after obstructive events have been eliminated. There is less evidence for the efficacy of CPAP in central sleep apnea syndromes.
Prediction equations, based on neck circumference, body mass index (BMI), and AHI, have been suggested for empiric CPAP pressures but these lack precision . They are not accurate enough to distinguish between patients who do or do not have OSA; however, they may be useful in prioritizing patients for split-night polysomnography . In certain situations, a re-titration study may be indicated, eg, when there is weight change greater than 15%, persistent or recurrent symptoms, and for reassessment after upper airway surgery or treatment with oral appliances (OAs) . During the course of a titration study, positive airway pressure may need to be increased in the supine position or during REM sleep. One study noted that in most patients who had OSA, the optimal CPAP level was significantly higher in the supine position than it was in the lateral position . This finding was true for REM and non-REM sleep, for obese and non-obese patients, for patients who had different degrees of severity, and for young and old OSA patients. The authors concluded that no CPAP titration should be considered complete without the patient having slept in the supine posture during REM sleep. Nevertheless, the differences in optimal CPAP between the supine and lateral postures were similar, ranging between 2.31 and 2.66 cm H 2 O.
Frequently, diagnostic testing and CPAP titration can be accomplished in a split-night fashion for patients who have moderate to severe OSA. A split-night protocol, consisting of an initial diagnostic portion followed by a therapeutic titration, can determine the effective CPAP pressure , especially in patients who have an AHI greater than 20/h. But a split-night study may be unsatisfactory in some situations, such as when the duration of CPAP titration was short and when REM sleep was not achieved during the titration. Patients who have mild OSA would be more likely to have unsuccessful split-night studies because more prolonged monitoring would be needed to establish the diagnosis . Conversely, a study using classic symptoms of OSAS as the indication for split-night studies found that there were no differences in long-term CPAP use compared with full-night studies and that it resulted in shorter time from referral to treatment .
Initiation of continuous positive airway pressure
Following a diagnostic nocturnal polysomnography or following the diagnostic portion of a split-night study, patients who meet diagnostic criteria for OSA and who opt for CPAP undergo CPAP titration in the sleep laboratory . This titration is done while monitoring electroencephalography, electrooculography, oronasal airflow, chest wall effort, body position, snoring microphone, electrocardiogram, and oximetry. The patient is initially educated about the indications for CPAP and is allowed to adapt to the equipment and different masks. An initial short period of desensitization before the study is recommended, which allows the patient to get accustomed to the idea of wearing the equipment through the night. An attended study is most accurate and allows for technologist intervention for mask leaks, lost leads, and adjustment of CPAP according to body positions and rapid eye movement (REM) sleep . No precise protocol for CPAP titration exists, but general recommendations have been established. Usually, one starts at a low pressure of 4 to 5 cm, gradually increasing by 1 to 2 cm every 15 to 20 minutes until the apneas, hypopneas, respiratory effort–related arousals, and snoring are abolished. Patients who hypoventilate or who have other comorbidities (eg, chronic obstructive pulmonary disease, congestive heart failure (CHF), neuromuscular disease) may require in-line oxygen to correct hypoxia, but generally only after obstructive events have been eliminated. There is less evidence for the efficacy of CPAP in central sleep apnea syndromes.
Prediction equations, based on neck circumference, body mass index (BMI), and AHI, have been suggested for empiric CPAP pressures but these lack precision . They are not accurate enough to distinguish between patients who do or do not have OSA; however, they may be useful in prioritizing patients for split-night polysomnography . In certain situations, a re-titration study may be indicated, eg, when there is weight change greater than 15%, persistent or recurrent symptoms, and for reassessment after upper airway surgery or treatment with oral appliances (OAs) . During the course of a titration study, positive airway pressure may need to be increased in the supine position or during REM sleep. One study noted that in most patients who had OSA, the optimal CPAP level was significantly higher in the supine position than it was in the lateral position . This finding was true for REM and non-REM sleep, for obese and non-obese patients, for patients who had different degrees of severity, and for young and old OSA patients. The authors concluded that no CPAP titration should be considered complete without the patient having slept in the supine posture during REM sleep. Nevertheless, the differences in optimal CPAP between the supine and lateral postures were similar, ranging between 2.31 and 2.66 cm H 2 O.
Frequently, diagnostic testing and CPAP titration can be accomplished in a split-night fashion for patients who have moderate to severe OSA. A split-night protocol, consisting of an initial diagnostic portion followed by a therapeutic titration, can determine the effective CPAP pressure , especially in patients who have an AHI greater than 20/h. But a split-night study may be unsatisfactory in some situations, such as when the duration of CPAP titration was short and when REM sleep was not achieved during the titration. Patients who have mild OSA would be more likely to have unsuccessful split-night studies because more prolonged monitoring would be needed to establish the diagnosis . Conversely, a study using classic symptoms of OSAS as the indication for split-night studies found that there were no differences in long-term CPAP use compared with full-night studies and that it resulted in shorter time from referral to treatment .
Special positive airway pressure delivery systems
Bilevel positive airway pressure (PAP) systems allow for independent adjustment of inspiratory and expiratory pressures and can provide partial spontaneous ventilatory assist in various settings, including obesity hypoventilation, neuromuscular disease, and reduced ventilatory drive . Bilevel PAP may be indicated when patients cannot tolerate CPAP because of discomfort while exhaling against positive pressure or when aerophagia is problematic. Bilevel pressure is not routinely indicated as an alternative to CPAP in OSA because, although the mean pressure used may be lower, in most cases this does not affect compliance or increase the hours of usage .
Advances in CPAP technology have yielded CPAP devices with sensors, which indirectly detect airflow and automatically adjust pressure according to built-in algorithms. In theory, such autotitrating PAP (APAP) devices automatically adjust the pressure up or down to maintain upper airway patency at the lowest effective pressure. APAP devices differ greatly in their detection algorithms, limiting comparison between machines. Devices using differing technologies may yield dissimilar results in a given patient. The efficacy of APAP for the treatment of OSAS has been reviewed in detail and the American Academy of Sleep Medicine (AASM) has made recommendations regarding the use of these devices. APAP may be used for treatment only after an attended titration with standard CPAP or APAP is completed. It is not currently recommended for patients who have CHF, significant lung disease, obesity, hypoventilation, or respiratory failure. Patients who do not snore (because of surgery or naturally) should not be titrated with an APAP device that relies solely on vibration or sound to monitor compromised airflow. Mask leaks may prevent adequate titration with APAP. APAP is not recommended for use in split-night studies.
Studies have suggested that APAP therapy reduces the mean PAP requirements, which is believed to positively impact treatment adherence. The efficacy of three different methods of CPAP delivery—autotitration pressure throughout, autotitration pressure for 1 week followed by fixed pressure thereafter (at 95th centile), and fixed pressure determined by an algorithm—was assessed in a randomized prospective study over a period of 6 months, with patients and investigators blinded to group allocation . There were no significant differences in any of the outcome measures, including indicators of daytime sleepiness (Epworth Sleepiness Scale [ESS] scores), maintenance of wakefulness test, 24-hour blood pressure, general health (short form-36 [SF-36]), and sleep apnea–related quality of life. The pressures in the 95th centile CPAP and 1 week autotitration pressure groups were higher than in the algorithm group, but the median pressures were lowest in the 6-month autotitration group. A more recent meta-analysis investigated the question of the efficacy of APAP over CPAP . Specifically, the study investigated the relative effectiveness of devices in reducing the AHI, reducing the mean airway pressure, improving subjective sleepiness, and improving treatment adherence in patients who had OSA. Results from nine randomized trials with a total of 282 patients were analyzed. Compared with CPAP, there was no significant advantage of APAP in reducing AHI or sleepiness (pooled APAP-CPAP posttreatment RDI and ESS score = −0.20 events per hour, 95% confidence interval:[−0.74, 0.35], and −0.56 [−1.4, 0.3], respectively). The use of APAP reduced the mean applied pressure across the night by 2.2 cm water [1.9, 2.5] compared with CPAP. Adherence with therapy was not substantially improved with APAP. Compared with standard CPAP, APAP was associated with a greater reduction in mean pressure but there were no differences in degree of adherence, ability to eliminate respiratory events, or ability to improve subjective sleepiness. Given that APAP is more costly than standard CPAP, the investigators suggested that APAP should not be considered as first-line chronic therapy in all patients who have OSA but could be considered in special situations (eg, home titrations, detection of mouth leak) or in certain subgroups of patients who have OSA, including patients intolerant of CPAP or patients who have posture-dependent or sleep-stage dependent OSA. A recent Cochrane Review also concluded that auto-adjusting and bilevel devices did not produce a significant difference in adherence when compared with CPAP . Studies investigating long-term treatment outcomes with APAP versus CPAP are awaited.
A pressure-relief PAP device (C-Flex, Respironics) was introduced with the aim of increasing comfort during exhalation to improve treatment adherence. With C-Flex, the airway pressure alternates between exhalation and inhalation on a breath-by-breath basis such that the pressure is reduced during early exhalation and increased toward the end of inhalation. A nonrandomized trial comparing this device with CPAP over a period of 3 months found that adherence was higher in the C-Flex group (4.8 ± 2.4 versus 3.1 ± 2.8 hours, mean ± SD), but without significant differences in subjective sleepiness or functional outcomes . Additionally, two randomized, controlled, double-blind trials did not find any significant compliance differences at 1 month as determined by percentage of nights with at least 4 hours of use (80.5% ± 24% versus 77.6% ± 24.8%) and hours of use per night (5.6 ± 1.4 versus 5.6 ± 1.7 hours per night). Similar improvements were seen in scores on the ESS and Functional Outcomes of Sleep Questionnaire (FOSQ) . Oral dryness with C-Flex was significantly lower than with constant CPAP but the effect did not last after 7 weeks .
Potential problems with continuous positive airway pressure
The efficacy of CPAP as a treatment modality depends on long-term compliance, which in turn is related to the frequency of side effects and discomfort with CPAP use, among other factors. The common side effects of CPAP are related to nasal symptoms of dryness, congestion, sneezing, and rhinorrhea, which may affect 25% to 65% of the users . Patients may also complain of sinusitis, conjunctivitis, sore eyes, and red eyes. Other complaints include claustrophobia and discomfort from the pressurized air, including difficulty exhaling. Pressure sores may develop on the face from the mask. Some patients may complain of difficulty tolerating noise from the equipment. In one study, 50% of the patients complained of at least one side effect related to the mask, including allergic reaction, abrasion of the bridge of the nose, or mask air leaks; 65% complained of dryness of the nose or mouth; sneezing and nasal drip were noted in 35%, nasal congestion in 25% of the subjects, air swallowing in 16%, sinusitis in 8%, and nosebleed in 4% of the subjects . There was no correlation between the side effects and the level of pressure used during nasal CPAP. Although machine noise was noted by 34% of patients in this study, it is probably less of a problem today with newer, quieter machines. There have been case reports of chest discomfort from the pressure, one case of pneumocephalus , a postcoronary artery bypass pneumopericardium , and one case report of meningitis related to recurrent sinusitis . There are no absolute contraindications for CPAP use but bouts of recurrent acute sinusitis following CPAP use may be a relative contraindication . There is a potential risk for rebreathing in the event of equipment or electric failure in the absence of an alarm system .
Optimizing continuous positive airway pressure use
Nonadherence patterns
Nonadherence with CPAP is a barrier to effective treatment of OSAS. From a study of daily covertly monitored patients who had severe OSAS, 50% were consistent users of CPAP, using it more than 90% of the nights for an average of 6.22 ± 1.2 hours per night. The remaining 50% were intermittent users, averaging from 3.45 ± 1.94 hours per night. Intermittent users had more OSAS symptoms caused by inadequate therapy . The pattern of nonadherence was established early in treatment (ie, within the first week of therapy) and compliance at 1 month predicted compliance at 3 months. Kribbs and colleagues found that only 46% of patients used at least 4 hours of CPAP on 70% of the nights. A 10% differential existed between mask-on and machine-on time. Patients generally overestimate the hours of CPAP use by about 1 hour. Individual patient self-reports should thus be considered as unreliable for assessing compliance. Most CPAP machines have built-in meters to record the duration of time that the machine has been running or the duration that a mask has been in actual use. These can be used to objectively measure adherence to CPAP. Monitoring of CPAP adherence by these built-in timers has been recommended as standard of practice by the AASM . Adherence data can be obtained and sent to the providers by way of a smartcard or transmission to a website. This process allows monitoring of CPAP use with immediate intervention when there is less than optimal use.
Predictors of continuous positive airway pressure compliance
Predictors of continued CPAP use include severity of sleepiness and severity of AHI and snoring. The daily use of nasal CPAP was significantly correlated to the initial AHI in one study ( r = 0.37, P = .013) . Others have demonstrated that subjective CPAP use correlated with sleepiness and ESS before treatment but not with any objective index of severity of OSA . Similarly, Scharf and colleagues did not find that long-term adherence was related to disease severity as measured by the AHI but was related to an ESS score of more than 10. In one study, long-term use could be predicted most reliably by the average nightly use of CPAP during the first 3 months ; patients using CPAP for less than 2 hours per night at 3 months were unlikely to continue with long-term treatment. More than 85% of the long-term users had an average use of at least 3 hours, however. CPAP use was negatively correlated with “degree of nuisance” of CPAP therapy . CPAP mask problems and side effects were not associated with reduced CPAP use, but complaints of awakenings, noise, and sore eyes from CPAP correlated negatively with reported use . In a separate study, frequently identified barriers to treatment use were nasal stuffiness, claustrophobia, and disturbing the bed partner’s sleep . Age, gender, socioeconomic status, race, body mass index, or time spent with oxygen saturation of less than 90% did not predict CPAP use . Patients used CPAP much more if they were aware of the beneficial effects of CPAP . Perceived improvement in symptoms after CPAP use has also been shown to be related to better adherence . Although 50% of the subjects did not perceive problems with concentration, sexual performance, sleepy driving, or an accident as related to sleep apnea, more than 60% of the subjects acknowledged most of the benefits of CPAP presented to them . Overall CPAP use in those taking CPAP home was 68% at 5 years .
The type of device does not does not determine compliance. The Cochrane Review did not find a significant difference in adherence by type of device used, whether auto-adjusting PAP, bilevel PAP, or fixed CPAP . A study investigating the contribution of flexible pressure (C-Flex) and standard fixed pressure CPAP adherence noted that compared with fixed-pressure CPAP, adherence with devices using flexible pressure was almost 1 hour longer during initial use (2 to 4 weeks) and 2 hours longer with long-term use (9 to 12 weeks). This finding was not replicated in a more recent study , however, where nightly use was similar with both devices at 7 weeks.
Strategies to improve adherence
Adequate education about the disease process and PAP device, mask interface, humidification, and regular follow-up of patients with troubleshooting of problems can help to improve adherence with PAP use. Measures to counteract the side effects of CPAP have been found to improve compliance . Proper mask selection, humidification (see later discussion), nasal steroids and anticholinergic nasal sprays , use of chinstrap, pressure ramp, and, in certain instances, bilevel airway pressure or flexible pressure are some of the key interventions.
Type of interface and positive airway pressure device
Available interfaces include nose mask, nasal pillows, full-face mask, and oral devices. The adequacy and comfort of mask fit and appropriate selection of pressure level greatly affect compliance. Many different PAP interfaces are available that are designed to increase compliance. Although the face mask may be an alternative interface in patients who cannot tolerate nasal CPAP because of nasal congestion, the number of nights on CPAP were similar regardless of the type of mask used . Conversely, another study noted greater adherence with nasal versus a full-face mask because of greater comfort and lower ESS scores . The face mask was associated with fewer complaints of dry mouth and dry nose, but more complaints of sore eyes, air leaks, and claustrophobia . Patients who complain of claustrophobia may be given an oronasal mask, nasal pillows, or oral mask following a desensitization protocol. When claustrophobia or other CPAP use–related anxiety persists, desensitization protocols often become essential . Two randomized controlled trials (RCT) comparing nasal versus the oral mask (Oracle, Fisher-Paykel) in moderate to severe OSA found no significant differences in CPAP adherence at one month (0.3 hours per night) or side effects . Although polysomnographic variables, ESS scores, OSA-related symptoms, and CPAP compliance were significantly improved from baseline, these were not significantly different between the two interfaces. In another study, however, the main limitations of the Oracle mask were upper airway dryness and “rain-out” associated with heated humidification, resulting in more drop-outs . A randomized controlled crossover trial comparing nasal pillows and nasal masks noted that the nightly minutes of use were similar (nasal pillows: 223 minutes versus nasal mask: 288 minutes) over a 3-week period in patients receiving CPAP at 14 cm or less with similar ESS and FOSQ scores. On the other hand, fewer side effects with less sleep difficulty and air leak occurred with nasal pillows .
Persistence of sleep apnea may occur in patients treated with CPAP. This underscores the need for regular follow-up and adjustment of mask interface to treat OSAS. In one study, persistence of sleep apnea was defined as AHI greater than 10 per hour and occurred in 17% of the study subjects . There were no significant differences between participants who had persistent OSA and those who had AHI less than 5 per hour with regard to age, sex, time since diagnosis, reported snoring, change in weight, or quality of life. Persistence of sleep apnea was related to unresolved mouth or mask leak . These patients complained of morning headaches and nonrestorative sleep. The AASM recommends close follow-up of patients to troubleshoot for mask and PAP device problems and manage side effects, especially during the first few weeks of PAP use .
Heated humidification
The flow of cold air dries the nasal mucosa and may increase nasal airway resistance. Excessive drying of nasal mucosa has been shown to induce the release of vasoactive leukotrienes leading to increased resistance and mouth breathing, which in turn leads to drying of mouth mucosa . Humidification can be in the form of cold passover humidity or heated humidity. Although both types of humidity provided greater satisfaction compared with no humidity, patients were more refreshed and complained of fewer adverse effects, such as dry mouth or dry nose, with heated versus cold humidification . Compliance was improved with heated but not cold humidity but there was no change in the ESS scores. In these studies, the predictors for the need for additional heated humidification with nasal CPAP included age greater than 60 years, drying medication, symptoms of chronic mucosal disease, and previous uvulopalatopharyngoplasty. Fifty-six percent of the patients described development of disabling nasal discomfort with nasal CPAP. Heated humidification was necessary in 50% of the patients complaining of nasal discomfort after failure of cold humidification . In a recent study, while heated humidity did not seem to improve long-term (3-month and 12-month) compliance rates, individual symptoms of dry nose and dry mouth and throat were significantly lower in the heated humidification group . Radiofrequency reduction of nasal turbinate hypertrophy may benefit nasal obstruction and hence compliance with CPAP use .
Education and cognitive behavioral therapy
Studies have also shown that consistent follow-up, troubleshooting, intensive support, and regular feedback to patients and physicians can improve CPAP compliance rates to 85% over a period of 6 months . Patients may lack appreciation for their own impairment and the consequences of untreated OSA; hence, it is possible that some patients may develop perceptions that are not conducive to taking responsibility for their own treatment. Education with an additional phone call or printed literature about CPAP use can elicit greater compliance at 4 weeks from patients especially when applied at the start of CPAP therapy compared with no additional intervention . Additionally, an investigator-developed 15-minute videotape, using patients from different ethnicities discussing misconceptions about sleep apnea and barriers to use, significantly increased CPAP compliance and return for 1-month clinic visit than that in the control group . In patients who had OSA (mean RDI 54.2 ± 25.5/h), active coping, which included confrontive coping and planful problem solving, rather than passive coping, was associated with increased CPAP compliance (nightly CPAP use of 4.4 to 7.7 hours per night) . Individuals who engaged in active coping strategies with new and difficult situations had greater CPAP compliance, whereas emotion variables, such as depressed mood, were unrelated to compliance. Active coping independently explained 16% of the variance in CPAP compliance, whereas more than 30% of the variance in CPAP compliance was explained by knowing the initial RDI, ESS, and compliance scores. Encouraging patients to use coping techniques, such as planful problem solving, thus helps to improve compliance with CPAP . In addition, cognitive-behavioral therapy (two 45-minute sessions) with education regarding the consequences and efficacy of CPAP has been shown to improve compliance . After 12 weeks of use subjects in the intervention group used CPAP 7.8 hours per night compared with 4.6 hours per night in the control group . Hoy and colleagues found that if patients themselves initiated treatment of sleep apnea, then they were more likely to be adherent to treatment than if it was at the recommendation of the bed partner.
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