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.
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