What’s New in the Patient Safety World
September 2012
Obstructive Sleep Apnea in Stroke Patients
A variety of
complications may occur in patients with acute stroke. Aspriation pneumonia,
UTI, decubiti, contractures, DVT and pulmonary embolism are some of the more
common complications. Because patients with stroke also share numerous risk
factors for coronary artery disease, they may also be susceptible to myocardial
ischemia and arrhythmias. But we also see some patients who unexpectedly die
suddenly after stroke without good explanation. Some have speculated on the
possible role of sleep apnea in such cases.
A new study (Aaronson
2012) assessed use of nocturnal pulse oximetry to screen for sleep apnea in
stroke patients in an acute rehabilitation setting. They performed both
nocturnal oximetry and polysomnography on 56 stroke patients and found a 46%
prevalence of sleep apnea syndrome in those patients. Patients with sleep apnea
were older, more likely to be male, and had higher BMI’s than those without
sleep apnea. But subtype of stroke, stroke location, and degree of disability
did not correlate with sleep apnea.
The oxygen
desaturation index (ODI) on nocturnal pulse oximetry did correlate very well
with the apnea-hypopnea index (AHI) on polysomnography. And the sensitivity,
specificity, and positive and negative predictive values of nocturnal oximetry
for sleep apnea were quite good. In fact, in a multiple regression model the
ODI was the sole predictor of sleep apnea. For an ODI cutoff of 15 or more the
sensitivity of nocturnal oximetry was 77%, specificity 100%, and positive
predictive value 100% for sleep apnea. A negative result lowered the chance of
sleep apnea to 17%.
Since
polysomnography may not be readily available or convenient in many settings
rendering care for stroke patients, nocturnal oximetry seems to be a reasonable
way of identifying patients with likely sleep apnea. Even if such patients are
not begun on treatments such as CPAP, knowing they likely have sleep apnea
should lead to avoidance of certain medications (opioids, sedative/hypnotics,
etc.) that may exacerbate sleep apnea. It might also have implications for
positioning of patients during sleep (since many sleep apnea patients do worse
when supine).
Obviously, more work needs to be done in determining best practices for handling sleep apnea in stroke patients. But this study certainly highlights the scope of the problem and should spur such further work.
References:
Aaronson JA, van
Bezeij T, van den Aardweg jg, et al. Diagnostic Accuracy of Nocturnal Oximetry
for Detection of Sleep Apnea Syndrome in Stroke Rehabilitation. Stroke 2012; first published on July
19 2012 as doi:10.1161/STROKEAHA.112.665414
http://stroke.ahajournals.org/content/early/2012/07/19/STROKEAHA.112.665414.abstract
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