Measuring changes in cerebral oxygenation and hemodynamics during obstructive sleep apnea by functional near infrared spectroscopy

Abstract

One of the most important integral part of human existence is sleep. It has beenthought that sleep has a recovery function for brain. This importance opens a new area ofresearch about sleep disorders. Obstructive sleep apnea occurs with the absence of airflow for more than ten seconds despite continuing ventilatory efforts, several times during sleepwith a reduction of arterial oxygen saturation (SaO2).Sleep apnea can clinically be detected by overnight polysomnography studies, butthese studies do not give information about brain hemodynamics and tissue oxygenation. Functional imaging of brain by near infrared spectroscopy (fNIRS), gives chance tomeasure specific biochemical markers. It is also possible to continuously andnoninvasively measure cerebral oxygenation by NIRS.In this study, by using functional near infrared spectroscopy synchronously with polysomnography; cerebral tissue oxygenation and hemodynamics of six obstructive sleepapnea (OSA) patients were measured with the certain polysomnography parameters, likeSaO2 and respiratory signal.During apneic events, cerebral tissue deoxygenation was not as significant as deoxygenation in peripheral tissues. In this study, during apneic events, increase in deoxyhemoglobinand total hemoglobin were observed in combination with a lesser increase inoxy-hemoglobin in cerebral tissue Phase differences between breathing, arterial oxygensaturation and cerebral tissue hemodynamics were also observed during this study.|Keywords: Sleep, Apnea, Functional near infrared spectroscopy, Brain hemodynamics.