CPAP Continues to Underperform

Continuous positive airway pressure (CPAP) is the first-line treatment for obstructive sleep apnea (OSA). Over the past 20 years, the indications for prescribing CPAP for sleep-related breathing disorders have expanded to include a majority of the adult population. CPAP is purported to reduce blood pressure, cure headaches, improve memory, and reduce weight. Unsubstantiated claims surrounding the use of the machine include promotions at work, improving your hairline, and making your car run faster.

The problem is, the threshold for diagnosing sleep apnea is so low that a majority of the adult male population will qualify as having this "disease." If you're a man over 60, your pretest probability for having OSA is close to 100%. The data for CPAP improving daytime symptoms for patients with moderate to severe disease, when hypopnea scoring requires desaturation, is quite strong. Outside this scenario, CPAP as a "cure-all" has far less support.

For example, let's look at CPAP as a therapy for atrial fibrillation (AF). For more than a decade, the cardiologists at my institution have been sending every one of their patients with AF to sleep medicine for polysomnography. AF is most common in older persons, and OSA prevalence in this group is close to 100% using modern sensors and the American Academy of Sleep Medicine (AASM) recommendation to score hypopneas using arousals. Therefore, the prevalence of OSA among those with AF is extraordinarily high.

Physiologically, it's easy to make the case that OSA leads to AF. Arousals and obstructions during sleep can increase sympathetic tone, cause intrathoracic pressure swings, and prevent the expected decrease in blood pressure that occurs during sleep. CPAP should eliminate all these problems and reduce AF. Case closed, right?

In reality, we don't know. Randomized trials on AF have been equivocal to this point. A new randomized trial published online suggests that CPAP does not reduce paroxysmal AF. In fact, the trial suggests CPAP doesn't do much of anything at all, and may even be harmful. For those familiar with the SERVE-HF trial and the ensuing debate over the potential cardiac benefits from Cheyne-Stokes respirations, this CPAP story should sound familiar. Often a therapy is applied for years on the basis of sound physiologic principles but ultimately fails on first contact with a randomized trial.

To be clear, CPAP is a great therapy that helps many, many people feel better. In this author's opinion though, the chasm that separates alleged benefits from proven outcomes is quite wide. Contrary to what the AASM might say, and what many sleep physicians believe, not everyone has a sleep-related breathing disorder that will benefit from CPAP. Almost everyone with AF has OSA by current scoring criteria, but we lack the data to prove they will benefit from CPAP.

Aaron B. Holley, MD, is an associate professor of medicine at Uniformed Services University and program director of pulmonary and critical care medicine at Walter Reed National Military Medical Center. He covers a wide range of topics in pulmonary, critical care, and sleep medicine.

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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.

Cite this: Aaron B. Holley. Continuous Positive Airway Pressure Continues to Underperform - Medscape - Jun 17, 2021.

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