Noninvasive monitoring adult hemodynamic and oxygenation variables´ changes in response to sensory stimulation by near-infrared spectroscopy

Near-infrared spectroscopy was used to measure oxy-hemoglobin concentration ([HbO₂]), deoxy-hemoglobin concentration ([Hb]), total hemoglobin concentration ([HbT]), oxygen saturation of hemoglobin (SO₂), cerebral blood flow (CBF), and cerebral blood volume (CBV). The purpose of this study was to find how these parameters changed when adults were excited, scared or waked by sensory stimulations. The tests were made on 18 healthy adult volunteers. High- and low-level of each variable with mean flows for all 18 subjects in the sleeping state are showed as 70plusmn10 and 19plusmn2 muM/1 for [HbO₂], 18plusmn2 and 11plusmn2 muM/1 for [Hb], 88plusmn8 and 30plusmn2 muM/1 for [HbT], 77plusmn4% and 55plusmn5% for SO₂, 37plusmn2 and 13plusmn3 mlldr100g^-1ldr min^-1 for CBF, 2.3plusmn0.5 and 1.5plusmn0.13 ml/100g for CBV. Analysis of changes in these variables when adults waked from the sleep state or excited or scared in the wake state are given to prove brain activity has a close relationship with cerebral local oxygen metabolism and hemodynamic variables. This noninvasive technique may be a powerful tool for brain functional research.