Positive airway pressure: Making an impact on sleep apnea

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Release date: September 1, 2019
Expiration date: August 31, 2022
Estimated time of completion: 0.75 hour

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Positive airway pressure (PAP) devices deliver a pressurized column of air to open the airway in patients with sleep apnea. For patients with moderate to severe sleep apnea, PAP therapy is the gold standard for treatment, with demonstrated improvements in daytime sleepiness and cardiovascular measures that are superior to conservative treatments. For a variety of reasons, adherence to PAP therapy is a challenge for many patients, resulting in deficits in the frequency and duration of use. To improve use and compliance to therapy, several advanced features are available to enhance comfort, pressure, and humidification factors associated with PAP devices. Patient motivation strategies such as motivational interviews, desensitization protocols, and PAP “NAPs” are also being employed to improve adherence to therapy.


  • PAP therapy is the gold standard treatment for moderate to severe sleep apnea.
  • Adherence to PAP therapy remains a challenge due to the PAP device itself and various patient comfort factors.
  • Features of PAP devices that may improve adherence are advanced pressure control, including ramp, auto and bilevel, heated humidification, and compliance data reporting.
  • Strategies to motivate patients to use PAP therapy include motivational interviewing, desensitization, and PAP “NAPs.”



Figure 1. Obstructed airway (left) is opened with a column of air delivered using positive airway pressure therapy (right).

Figure 1. Obstructed airway (left) is opened with a column of air delivered using positive airway pressure therapy (right).

Positive airway pressure (PAP) therapy is used to open an obstructed upper airway (Figure 1). PAP therapy consists of a small bedside unit that creates a pressurized column of air that is delivered through tubing to a facial interface, which can be nasal, oral, or both. Collin Sullivan, MD, created the nasal continuous PAP (CPAP) in 1982 using parts of a vacuum cleaner to create positive pressure that successfully resolved hypoxemia in a patient.1 Today, the various forms of PAP therapy include CPAP, the most common, auto-PAP (APAP), and bilevel PAP (BiPAP).


The American Academy of Sleep Medicine practice guidelines for PAP are based on 342 articles, most rated as evidence levels I and II, concluding that CPAP is superior to conservative treatment to:

  • Eliminate respiratory disturbances
  • Reduce the apnea–hypopnea index
  • Decrease the arousal index on electroencephalogram
  • Increase in the total amount of slow-wave or N3 sleep
  • Reduce daytime sleepiness.2

These practice parameters are based on evidence of improved daytime sleepiness and reduced incidence of cardiovascular events in patients with moderate to severe obstructive sleep apnea (OSA) treated with PAP. The evidence is less clear for neurocognitive markers and cardiovascular events in the treatment of patients with mild sleep apnea.


A study evaluated sleepiness outcomes in 149 patients with severe sleep apnea with an average apnea–hypopnea index of 69 relative to the duration of nightly CPAP use. Sleepiness was measured using the Functional Outcomes of Sleep Questionnaire, Epworth Sleepiness Scale, and Multiple Sleep Latency Test. Results suggest that a greater percentage of patients had improved daytime sleepiness as the total hours of sleep using CPAP increased.3

The Apnea Positive Pressure Long-term Efficacy Study (APPLES) was a 6-month, multicenter, randomized study of neurocognitive function in patients with OSA (N = 1,098).4 Subjective sleepiness as measured by the Epworth Sleepiness Scale showed statistically significant improvement at 2 and 6 months for patients with moderate to severe OSA using CPAP. Objective sleepiness as measured by the Maintenance of Wakefulness Test showed statistically significant improvement (ie, improved daytime alertness) at 2 and 6 months for patients with severe OSA using CPAP.

Neurocognitive function

APPLES also tested for attention and psycho­motor function as well as verbal learning and memory, though no statistically significant improvements were found in these parameters.4 Executive function and frontal lobe function showed transient improvement at 2 months in patients with severe sleep apnea using CPAP, but the improvement was not statistically significant at 6 months.

Cardiovascular outcomes

Hypertension and cardiovascular disease. Use of CPAP therapy reduces blood pressure in individuals with hypertension. A study of 32 patients who had a baseline polysomnography with 19 hours of continuous mean arterial blood pressure monitoring were treated with therapeutic CPAP (n = 16) or subtherapeutic CPAP (n = 16).5 Therapeutic treatment with CPAP for patients with moderate to severe OSA resulted in statistically significant reductions in mean arterial pressure for both systolic and diastolic pressures. The blood pressure reductions achieved are estimated to reduce coronary artery diseases by 37% and stroke by 56%.5

The risk of cardiovascular events in men with severe sleep apnea is high but mitigated by the use of CPAP. In a cohort of 1,651 men, untreated severe sleep apnea resulted in a threefold increase in the rate of cardiovascular events per 1,000 patient-years compared with 4 other groups: a control group, men who snore, men with untreated mild to moderate sleep apnea, and men with OSA using CPAP.6 However, when men with severe sleep apnea use CPAP, the risk of cardiovascular events is reduced to the rate in men who snore.

Atrial fibrillation. In patients with atrial fibrillation treated with direct-current cardioversion-
defibrillation, the recurrence of atrial fibrillation at 12 months was greater in patients with untreated OSA (82%) compared with a control group (53%) and patients treated for OSA (42%).7

Heart failure. In a study of 24 patients with heart failure, an ejection fraction less than 45%, and OSA, patients were randomized to a control group for medical treatment or medical treatment and nasal CPAP for 1 month.8 In the CPAP group, mean systolic blood pressure and heart rate were reduced, resulting in an improved ejection fraction compared with baseline, as well as compared with patients in the control group.

In patients with heart failure (N = 66) with and without Cheyne-Stokes respirations in central sleep apnea, patients treated with CPAP were found to have a 60% relative risk reduction in mortality-cardiac transplant rate compared with the control group not using CPAP.9 Further stratification in this study showed that patients with significant Cheyne-Stokes respirations and central sleep apnea had an improved ejection fraction at 3 months and an 81% reduced mortality-cardiac transplant rate.9


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Alternative interventions for obstructive sleep apnea

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