Multichannel Monitoring of Cerebral Circulatory and Oxygenation Status Using Optical Topography during Deep Hypothermic Retrograde Cerebral Perfusion

Abstract

In this study, we evaluated changes in the cerebral circulatory and oxygenation status during deep hypothermic total circulatory arrest (TCA) and retrograde cerebral perfusion (RCP) using optical topography, a form of multichannel near-infrared spectrophotometry, to monitor the broad area perfused by the middle cerebral artery. Seven patients underwent thoracic aortic surgery with TCA and RCP via the superior vena cava. Pressure-regulated RCP was performed under pH-stat. No postoperative neurologic complications occurred. Using optical topography, the relative changes in oxy-, deoxy-, and total hemoglobin (oxy-Hb, deoxy-Hb, total Hb) were simultaneously measured from 24 points in both hemispheres. Deoxy-Hb was used for evaluating the regional oxygenation status under RCR The values of deoxy-Hb at the beginning of RCP were regarded as the basal values, and the rate of increase in deoxy-Hb per minute (deoxy-Hb/min) was calculated at each site. Deoxy-Hb/min during TCA was also calculated. In every case, both oxy-Hb and total Hb decreased and deoxy-Hb increased during TCA. When RCP was initiated, the decrease in oxy-Hb and the increase in deoxy-Hb were attenuated. Deoxy-Hb/min was significantly lower under RCP than during TCA in all portions. There was no significant difference of deoxy-Hb/min between any portions during RCP Our results showed that the status of circulation and oxygenation might be uniform in the brain during RCP and better than that under TCA.