1990 Fiscal Year Final Research Report Summary
Non-Invasive Study of Tissue Oxygen Metabolism Using Near Infrared laser Light ; Toward its Clinical Application
| Project/Area Number |
01480337
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Thoracic surgery
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| Research Institution | Asahikawa Medical College, Faculty of Medicine |
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Principal Investigator |
TAMURA Masahide MD Asahikawa Medical College First Dept. of Surgery Assistant Professor, 医学部 (30001887)
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| Co-Investigator(Kenkyū-buntansha) |
TAMURA Mamoru Ph. D Research Institute of Applied Electricity Hokkaido University Biophysics Divisio, 応用電気研究所, 教授 (80089888)
KUBO Yoshihiko MD Asahikawa Medical College First Dept. of Surgery Professor, 医学部, 教授 (70000990)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Near Infrared Light, / Laser Diodes, / Spectrophotometer, / Oxy-Hb Content, / Blood Volume, / Cytochrome Oxidase, / Non-invasive Measurement, / New Technique |
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| Research Abstract |
A new protable high performance apparatus for near infrared (NIR) laser spectrophotometry was developed to monitor the oxygenation state in human brain. Three different wavelengths of 780, 805 and 830nm of the NIR laser beam were used and each laser light illuminated alternatively the head through a fiber optic bundle. The amount of light reflected by or transmitted from the tissue was detected by the photomultiplier or silicone photodiode. The output signals of the photodiode were processed by a microcomputer, and the time course of calculated oxy, deoxy and total (oxy^+deoxy) hemoglobin (Hb) values were recorded in real time using the equations developed in our lavoratory. The calculation equations were verified in vivo with the rat head to confirm the reliability and acceptability of our methodology. NIR monitring was applied to 20 cases of cardiopulmonaly bypass patients in reflectance mode. The results demonstrated that in current CPB technique, the cerebral oxygenation levels during the bypass were maintained within the physiological range and the changes en the brain blood volume corresponded well to the pump flow balance. That is, the brain oxygenaation level was maintained roughly constant at a mean perfusion pressure of over 60mmHg during CPB, whereas below 50mmHg, a progressive decline in the Hb oxygenation was observed. These findings led us to conclude that non-invasive monitoring of cerebral oxygenation using NIR light can provide valuable data at the bed side about tissue metabolism and allow for the proper management of critical patients.
The problems that remain to be solved with this system include : 1) the absolute quantification of the changes in cerebral oxygenation and blood volume, 2) clinical introduction of a cytochrome oxidase redox measuring system to obtain information concerning ; the brain cell functions directory and 3) a further clinical evaluation of NIR informations obtained so far.
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