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The majority of acute stroke patients had sleep apnea. Auto-CPAP was well tolerated, appears to improve neurological recovery from stroke, and may represent a new therapeutic approach for selected patients with acute cerebral infarction.

Obstructive sleep apnea (OSA) increases the risk of stroke independent of known vascular and metabolic risk factors. Although patients with OSA have higher prevalence of hypertension and evidence of hypercoagulability, the mechanism of this increased risk is unknown. Obstructive apnea events are associated with surges in blood pressure, hypercapnia, and fluctuations in cerebral blood flow. These perturbations can adversely affect the cerebral circulation. We hypothesized that patients with OSA have impaired cerebral autoregulation, which may contribute to the increased risk of cerebral ischemia and stroke. We examined cerebral autoregulation in patients with and without OSA by measuring cerebral artery blood flow velocity (CBFV) by using transcranial Doppler ultrasound and arterial blood pressure using finger pulse photoplethysmography during orthostatic hypotension and recovery as well as during 5% CO(2) inhalation. Cerebral vascular conductance and reactivity were determined. Forty-eight subjects, 26 controls (age 41.0+/-2.3 yr) and 22 OSA (age 46.8+/-2.3 yr) free of cerebrovascular and active coronary artery disease participated in this study. OSA patients had a mean apnea-hypopnea index of 78.4+/-7.1 vs. 1.8+/-0.3 events/h in controls. The oxygen saturation during sleep was significantly lower in the OSA group (78+/-2%) vs. 91+/-1% in controls. The dynamic vascular analysis showed mean CBFV was significantly lower in OSA patients compared with controls (48+/-3 vs. 55+/-2 cm/s; P <0.05, respectively). The OSA group had a lower rate of recovery of cerebrovascular conductance for a given drop in blood pressure compared with controls (0.06+/-0.02 vs. 0.20+/-0.06 cm.s(-2).mmHg(-1); P <0.05). There was no difference in cerebrovascular vasodilatation in response to CO(2). The findings showed that patients with OSA have decreased CBFV at baseline and delayed cerebrovascular compensatory response to changes in blood pressure but not to CO(2). These perturbations may increase the risk of cerebral ischemia during obstructive apnea.

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Background Transient ischemic attack (TIA) patients are at risk of recurrent vascular events. The primary objectives were to evaluate among TIA patients: the prevalence of sleep apnea, and among patients with sleep apnea auto-titrating continuous positive airway pressure (auto-CPAP) adherence. The secondary objective was to describe among TIA patients with sleep apnea, the recurrent vascular event rate by auto-CPAP use category. Methods All intervention patients received auto-CPAP for two nights, but only intervention patients with evidence of sleep apnea received auto-CPAP for the remainder of the 90-day period. Intervention patients received polysomnography at 90-days post-TIA. Control patients received polysomnography at baseline and at 90-days. Acceptable auto-CPAP adherence was defined as ≥4 hours/night for ≥75% nights. Vascular events included recurrent transient ischemic attack, stroke, hospitalization for congestive heart failure, myocardial infarction or death. Results We enrolled 70 acute TIA patients: intervention N=45 and control N=25. The majority of patients had sleep apnea: 57% at baseline and 59% at 90-days. Among the 30 intervention patients with airflow obstruction, 12 (40%) had acceptable auto-CPAP adherence, 18 (60%) had some use, and none had no use. Three intervention patients (12%) had recurrent events compared with 1 (2%, p=0.13) control patient. The vascular event rate was highest among sleep apnea patients with no CPAP use: none, 16%; some, 5%; acceptable adherence 0%; p=0.08. Conclusions Sleep apnea is common among acute TIA patients. It appears feasible to provide auto-CPAP in the acute TIA period. Larger studies should evaluate whether a strategy of diagnosing and treating sleep apnea can reduce recurrent vascular events after TIA.