Nocturnal Desaturation in the Stroke Unit Is Associated With Wake-Up Ischemic Stroke

Abstract

Background and Purpose-Wake-up stroke (WUS) represents a quarter of all ischemic strokes and may be a specific subgroup. Nocturnal desaturation secondary to sleep-disordered breathing is an independent risk factor for stroke, but the association between nocturnal desaturation and WUS remains unclear. We investigated the relationship between nocturnal desaturation using oxygen desaturation index and WUS in patients with acute stroke in the stroke unit. Methods-A total of 298 patients admitted for acute ischemic stroke to the stroke unit between July 2013 and May 2015 were enrolled. The oxygen desaturation index was calculated using pulse oximetry data sampled every 1 minute during 9 hours on the first night (10:00 PM-7:00 AM) of the stroke unit admission, and nocturnal desaturation was defined as an oxygen desaturation index of 5 at least per hour. We compared the clinical characteristics and nocturnal desaturations between patients with and without WUS. Results-Among all patients (age, 67.7±12.6 years; male, 54.4%), 26.5% patients had WUS. The proportion of nocturnal desaturation was significantly greater in patients admitted with WUS (29.1% versus 12.3%, P=0.001). The age, sex, risk factors except for hyperlipidemia, stroke severity, and stroke mechanisms were similar between the 2 groups. After adjustment for covariates, it was found that nocturnal desaturation was significantly more common in the WUS group (odds ratio, 3.25; 95% confidence interval, 1.63-6.46). Conclusions-Nocturnal desaturation was more frequently observed in patients admitted with WUS during the first night in the stroke unit. This suggests that nocturnal desaturation is a possible modifiable risk factor for the occurrence of WUS. Baseline and Clinical AssessmentBaseline characteristics, including demographic data (age and sex) and vascular risk factors (hypertension, diabetes mellitus, hyperlipidemia, smoking history [current or past regular smoking], body mass index [BMI], and a past history of stroke/transient ischemic attack) were evaluated. Hypertension was defined as a history of antihypertensive treatment, a systolic blood pressure ≥140 mm Hg, or a diastolic blood pressure ≥90 mm Hg. 14 Hyperlipidemia was defined as a history of lipid-lowering medication, a serum total cholesterol level of >240 mg/dL, or a serum level of low-density lipoprotein cholesterol >160 mg/dL.15 Diabetes mellitus was defined as a hemoglobin A1C level of ≥6.5%, fasting blood glucose level of ≥7.0 mmol/L, nonfasting blood glucose level of ≥11.1 mmol/L, or the use of insulin or oral hypoglycemic drugs. 16 All of the patients were initially evaluated for stroke severity based on the National Institutes of Health Stroke Scale (NIHSS) neurological examination at SU admission. Ischemic strokes were categorized as large-artery atherosclerosis (LAA), small-vessel occlusion, cardioembolism, other determined, and undetermined based on the Trial of Org 10172 in Acute Stroke Treatment criteria. 17The ischemic lesion locations were divided into anterior circulation (ante...

Clinical Characteristics and Functional Outcomes of Wake-Up Stroke in the Chinese Population

“…To our knowledge, this is the first report to describe the proportion of WUS cases and examine differences in clinical characteristics and functional outcomes between WUS and non-WUS patients in the Chinese population. The finding that WUS accounted for 27.9% of ischemic strokes is consistent with conclusions from the International Stroke Trial and Canadian Stroke Registry [12] and other previous series [7,11,30]. Although controversy remains, our findings were also consistent with previous studies that reported similar distributions of risk factors, stroke severity, and TOAST classifications between cases of WUS and non-WUS [10,11,17,30,31].…”

“…The finding that WUS accounted for 27.9% of ischemic strokes is consistent with conclusions from the International Stroke Trial and Canadian Stroke Registry [12] and other previous series [7,11,30]. Although controversy remains, our findings were also consistent with previous studies that reported similar distributions of risk factors, stroke severity, and TOAST classifications between cases of WUS and non-WUS [10,11,17,30,31]. Lundholm et al [31] reported that WUS patients more frequently had previous stroke, which is also in accordance with our conclusion.…”

Pathophysiologic mechanisms, neuroimaging and treatment in wake-up stroke

“…A study in a South Korean stroke unit showed that nearly 30% of persons with WUS compared to just 12% of those with non-WUS had frequent nocturnal desaturation. 22 Patients with WUS appear to have similar age and gender distribution as those with non-WUS. 6 Mechanisms of WUS Analysis of International Stroke Trial data of over 17,000 acute ischemic strokes showed that WUS was more likely to occur by a lacunar mechanism and less likely to occur through a large vessel anterior circulation mechanism.…”

“…85 Evidence further suggests that severe OSA and severe hypoxemia occur with increased frequency in patients with WUS compared non-WUS. 18,22 In WUS, OSA may be directly related to the mechanism of stroke and it may be particularly important in these patients to conduct polysomnography to rule out OSA. Furthermore, severe hypoxemia in OSA can only be detrimental in the setting of a new stroke and may in part account for neurologic worsening and poor functional and cognitive outcomes, which are known to occur at higher rates when OSA co-occurs with stroke.…”

Increased Risk of Ischemic Stroke during Sleep in Apneic Patients

“…There are several reports of dyslipidemia being more frequent in WUS. 13 14 15 Lower blood pressure was suggested as a risk factor for WUS, 11 but this finding has not been replicated in other studies. Four 12 15 16 17 of six 11 12 13 15 16 17 studies that assessed OSA as a stroke risk factor found that habitual snoring or a higher apnea-hypopnea index in poststroke polysomnography (PSG) was more frequent among WUS patients ( Supplementary Table 1 in the online-only Data Supplement).…”