Associação entre a gravidade da apneia obstrutiva do sono e índice de vasorreatividade cerebral em pacientes com acidente vascular cerebral: estudo observacional transversal

Abstract

Obstructive Sleep Apnea (OSA) is common among patients with cardiovascular and cerebrovascular events and is being considered an independent risk factor for stroke. Despite this, the scientific understanding and documentation of this pathophysiological relationship is still under development. Transcranial Doppler is a non-invasive method of assessing cerebral blood flow and its possible changes. BHI (breath-holding index) is a method of assessing cerebral vasoreactivity, understood as the response of cerebral blood vessels to changes in the partial pressure of CO2 (carbon dioxide) and O2 (oxygen), through transcranial Doppler. Cerebral vasoreactivity is considered an adaptation to metabolic changes in cerebral vessels, and its impairment is a marker of stroke risk. Some studies have documented changes in cerebral vasoreactivity in patients with an increased risk of OSA or with OSA confirmed by polysomnography, in the general population. Cerebral vasoreactivity in patients with stroke and OSA confirmed by polysomnography has not yet been studied and may contribute to better understanding of the pathophysiology of cerebrovascular disease in the OSA population, allowing planning of possible therapeutic interventions. Aimed to identify a possible association between cerebral vasoreactivity - measured by BHI during transcranial Doppler - and the severity of OSA - measured by the AHI (Apnea Hypopnea Index) recorded in type 2 sleep monitoring (portable polysomnography), was evaluated a group of 83 patients with a confirmed diagnosis of stroke; aged over 18 years; with increased AHI (>5/h) in type 2 sleep monitoring; underwent assessment of cerebral vasoreactivity by transcranial Doppler, through BHI; who agreed to participate in the study through the Informed Consent Form (ICF). The mean age of the patients studied was 60.2 years, of which 62 (74.7%) were male. 48 (57.8%) patients had mild to moderate OSA (AHI<30/h) and 38 (45.8%) had altered cerebral vasoreactivity (BHI<0.69). A negative correlation was observed between the cerebral vasoreactivity index and the severity of OSA specifically during non-REM sleep (NREM sleep), with Spearman correlation = -0.23, p=0.036. In the linear regression adjusted for age and sex, however, this association was not maintained (effect = -0.01; 95% CI = -0.01 to 0.002, p=0.134). In the present study, therefore, changes in cerebral vasoreactivity were associated with OSA severity specifically during NREM sleep.