The results of a new study confirm there is an increased risk of death in patients who have had a stroke and who have moderate-to-severe obstructive sleep apnea (OSA), but suggest that continuous positive airway pressure (CPAP) therapy can markedly reduce this excess risk.

OSA occurs when the soft tissues at the back of the throat temporarily collapse during sleep, causing repeated breathing interruptions. Major symptoms include loud snoring and daytime sleepiness, which may result in irritability, cloudy thinking and concentration, an increased risk of traffic accidents.

An effective treatment for OSA is continuous positive airway pressure (CPAP), a method of respiratory ventilation in which a gentle continuous stream of air is delivered through a pliable mask worn over the nose during sleep. This keeps the airways open and prevents episodes of oxygen deprivation and arousal at night.

Good adherence to CPAP by stroke patients with moderate-to-severe OSA “achieves mortality similar to patients without OSA or with mild disease,” the study team reports in the July 1st issue of the American Journal of Critical Care Medicine.

OSA is now considered in many international guidelines as an independent cardiovascular risk factor, and particularly related to arterial hypertension,” Dr. Miguel Angel Martínez-García, of Equina General Hospital, Valencia, Spain, told Reuters Health.

“Furthermore, treatment with CPAP normalizes much of the respiratory events during sleep, which are the cause of this excess risk. It is therefore not surprising that treatment with CPAP, if it is used enough, offers cardiovascular protection to these patients.”

Martínez-García and colleagues studied 166 consecutive elderly ischemic stroke patients who underwent a diagnostic sleep study 2 months after acute stroke. Thirty-one patients did not have OSA; 39 had mild OSA and 96 had moderate-to-severe OSA (AHI 20 or greater).

API is an index used to assess the severity of sleep apnea based on the total number of complete breathing cessations and partial obstructions of breathing occurring per hour of sleep. The scores are classified as mild 5-15, moderate 15-30, and severe greater than 30. Those with an AHI 20 or greater were offered CPAP therapy.

During follow-up lasting 5 years, 81 patients (48.8 percent) died, and only 28 (29.2 percent) of the 96 patients on CPAP therapy were considered to have good long-term adherence to therapy.

According to the investigators, the 68 patients with moderate-to-severe OSA who did not tolerate CPAP well had a 2.69-times risk of death compared with patients with no or mild OSA.

There were no differences in death rates among patients without OSA, patients with mild OSA and patients who tolerated CPAP.

Increasing CPAP adherence in stroke patients with OSA is a “very difficult objective,” Martínez-García added in a statement, “because of the special characteristics of stroke patients, who tend to be elderly, may have neurological damage, and whose OSA symptoms are less likely to rapidly improve with CPAP treatment.

Adherence to CPAP treatment may be improved if physicians take more time to explain the cardiovascular benefits of treatment; stay in direct contact with patients; offer educational programs; and try to get them in a sleep lab for tests if problems with CPAP persist, the researcher added.

SOURCE: American Journal of Critical Care Medicine, July 1, 2009.