Keeping obstructive sleep apnea patients from sleeping on their backs has a long and evolving history. But emerging research supports a role for sleep position management in CSA patients as well.
About half of patients with obstructive sleep apnea (OSA) have positional OSA, which means that their apnea-hypopnea index (AHI) increases by at least 50% when they sleep on their backs compared with their sides. Although the reasons behind this are not totally understood, it makes sense intuitively: on one’s back, gravity pulls the tongue and pharynx down, potentially blocking the airway.1
Why sleeping position might affect patients with central sleep apnea (CSA), a disorder with roots in the brain rather than the airway, is perhaps less intuitive. But several studies suggest that it does play a role. One of the earliest, a 2005 Swedish study of 20 patients with heart failure and CSA during Cheyne-Stokes respiration, found that AHI dropped by nearly 50% when patients flipped from their backs to their sides.2 Similar results followed from studies in Australia3 and Japan,4 and in 2015, a study of 120 heart failure patients again demonstrated a reduction in apnea events in the lateral position, although the effect was less for those with CSA than with OSA.5
These observations raise an interesting question. Could CSA patients benefit from positional therapy? There is already a market for devices that encourage OSA sleepers to get off their backs. They range from extremely low tech (like this tennis ball T-shirt for $19) to quite sophisticated. There are pillows that can be placed in the bed or worn on a strap around the midsection. There are also devices worn like a collar or belt that vibrate when the wearer rolls onto their back. Some even record data that patients and clinicians can review the next day.
“The worst that can happen is that it doesn’t work,” says Nico De Vries, MD, PhD, an ear, nose, and throat specialist at the University of Amsterdam. De Vries works with Night Balance, a positional therapy device company in The Netherlands. He and his colleagues in Europe are currently writing up the results of a unique, multicenter positional therapy study on patients with CSA. Although the data has not yet been analyzed, De Vries says the results look promising.
“One thing that might happen is the AHI is lower, but you still have some residual snoring or you might find [the device] wakes you up a little bit,” he tells Sleep Review. “But mostly when there is an effect on sleep quality, it is almost always better instead of worse.”
Since positional therapy doesn’t involve drugs and is unlikely to produce side effects, its use in patients with CSA is appealing, says Timothy Morgenthaler, MD, a sleep specialist at the Mayo Clinic. But it’s not quite that simple.
“[I]t is actually quite difficult for people to sleep only in a non-supine posture,” he wrote to Sleep Review in an email. “Most people change positions many times each night and spend 20% or more of their time sleeping in a supine posture. Studies of positional therapy for obstructive sleep apnea syndrome show poor compliance over the long term, mostly related to discomfort with forced non-supine sleeping.”
In fact, a 2006 study found that more than half of patients using the tennis ball technique quit within a few months.6 And in a case study of positional CSA in a healthy young man, the patient declined to even try a pillow.7 Compliance with different devices varies but can be as low as 20% long term, although some patients reported using these devices temporarily as a means of training themselves to avoid the supine position.8
More recent research indicates that new technology might have much higher rates of compliance. Just last year, two studies co-authored by researchers affiliated with Night Shift9 and Night Balance 10 found that nearly 90% of patients wearing vibrational devices used them for at least 4 hours a night on most nights of long-term studies.
Aside from questions about effectiveness and compliance, investigators want to understand the mechanism at work. What does sleeping position have to do with apnea in patients with CSA?
There are two main hypotheses here, Morgenthaler says.
First, there is often upper airway occlusion at the termination of central sleep apneas, he says. That could stimulate upper airway receptors to inhibit central respiratory output. Second, there could be a lower cardiac output in the supine position that would affect venous return.
Others have suggested that sleeping supine impairs the respiratory feedback loop by reducing lung volume and oxygen storage.3
De Vries admits he doesn’t know why positional therapy makes a difference in CSA patients. “But the thing is even if you don’t understand how it works, the fact is it works in certain patients. So that alone is good news,” he says.
So should clinicians recommend positional therapy to their patients with CSA?
“One of the most important things to do would be to ensure that non-supine sleeping posture actually resulted in a satisfactory decline in central sleep apnea,” Morgenthaler says. “The other would be to keep in mind the compliance will probably not be very good over the long haul.”
In other words, maybe. For patients who find a device they can stick with, positional therapy could be part of their CSA treatment.
Rose Rimler is associate editor of Sleep Review.
Walsh JH, Leigh MS, Paduch A, et al. Effect of body posture on pharyngeal shape and size in adults with and without obstructive sleep apnea. Sleep. 2008;31(11):1543-1549.
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