Monitoring of brain oxygen status using near-infrared spectroscopy

Research Project

Project/Area Number	12671486
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Anesthesiology/Resuscitation studies
Research Institution	Kagoshima University
Principal Investigator	KAKIHANA Yasuyuki Kagoshima University, University Hospital, Faculty of Medicine, Assistant Professor, 医学部附属病院, 講師 (20264426)
Project Period (FY)	2000 – 2001
Project Status	Completed (Fiscal Year 2001)
Budget Amount *help	¥3,500,000 (Direct Cost: ¥3,500,000) Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000) Fiscal Year 2000: ¥2,700,000 (Direct Cost: ¥2,700,000)
Keywords	Near-infrared spectroscopy / cytochrome oxidase / deep hypothermic circulatory arrest / Cardiopulmonary bypass / cerebral oxygenation / 近赤外分光法 / チトクロームオキシターゼ / 超低体温 / 完全循環停止 / 脳酸素化状態 / S-100b蛋白 / 内頸静脈酸素飽和度 / チトフロームオキシターゼ / S-100蛋白
Research Abstract	Although the signal obtained for cytochrome oxydase (cyt. ox.) by near-infrared spectroscopy (NIRS) should be a useful indicator of intracellular hypoxia, the cyt. ox. signal represents a small component of the total change, and is therefore vulnerable to artifact. Recently it has been reported that cyt. ox. signal measured by NIRS is highly dependent on hematocrit. We have developed a new approach to the measurement of cyt. ox. in the brain involving the use of our new algorithm. In this study, we used NIRS device with our algorithm to examine possible cross-talk between the cytochrome and Hb signals while a change was occurring in the hemodilution. In another experiments, deep hypothermic circulatory arrest (DHCA) was induced for 60 min under 25℃ or 15℃ and evaluated the relationship between the redox behavior of cyt. ox. during DHCA and postoperative neurological prognosis. After institution of cardiopulmonary bypass (CPB), dogs received sodium cyanide to uncouple cytochrome from Hb. The hematocrit was then decreased from 35 to 5% by hemodilution. In this study, the Hb concentration calculated by NIRS device showed a strong positive correlation with hematocrit values in the blood during hemodilution. However, there was no correlation between the hematocrit and the cyt. ox. signal, which indicate that the cyt. ox. signal calculated using our recently developed algorithm was not much influenced by hematocrit. Furthermore, there was a good correlation between the redox behavior of cyt. ox. in the brain during DHCA and postoperative brain injury. In conclusion, the cyt. ox. signal measured by NIRS is dependent on the algorithm employed. Therefore, provided an accurate algorithm is employed the cyt. ox. signal measured by NIRS should provide us with important information even under various changes in hematocrit and/or hypothermia.