We aim to develop a novel kind of instrument for the non-invasive study of cerebral oxygenation during sleep apnea. Chronic, recurrent hypoxia during sleep leads to brain injury, which causes neuropsychological deficits and decline of cognitive function. Cerebrovascular accidents, including fatal strokes are not uncommon. Conventional polysomnography, a relatively expensive test, detects sleep apnea at various sleep stages and determines arterial oxygen saturation. However, current clinical methods do not provide information on brain oxygenation, which is important especially in subjects with preexisting anatomical or functional vascular pathology. We propose the development of instrumentation and experimental protocols to monitor cerebral hemodynamics during sleep apnea. The instrument will use near-infrared light, which penetrates several centimeters into tissues, passing through bony structures. Near-infrared Spectroscopy (NIRS) enables continuous real time measurements of changes in the hemoglobin oxygenation state and blood volume thus providing information on tissue oxygenation and hemodynamics. The instrumentation is based on two sensors, to allow differential measurements and the collection of optical data from both cerebral hemispheres. The measurements will be performed during rest, diurnal napping, and induced hypoxia on subjects with sleep apnea and on healthy volunteers. Our goal is the development of a reliable, cost efficient tool for early detection of cerebral hemodynamic abnormalities related to sleep apnea, for the screening and prevention of hypoxic brain damage.
The Absolute Near-Infrared Brain Oximeter developed for Sleep Apnea Syndrome Diagnosis can be utilized (a.) in the hospital environment as a complementary tool for polysomnographic studies; (b.) by the health provider, as a tool for assessing the neuropsychological conditions of people engaged in activities where the risks of the illness are extreme (drivers, pilots, soldiers, etc.); and, (c.) by the surgeon for monitoring brain oxygenation during open-heart surgery.