CONTINUOUS MONITORING OF CEREBRAL BLOOD VOLUME IN CATS USING REFLECTANCE SPECTROPHOTOMETER Shinzo Yoshida 1 , Hajime Handa 1 , Masatsune Ishikawa 1 , Osamu Hirai 1 , Soo-Ho Kim 1 1Department of Neurosurgery, Faculty of Medicine, Kyoto University pp.187-192
Published Date 1985/2/1
DOI https://doi.org/10.11477/mf.1406205465
  • Abstract
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The importance of cerebral blood volume (CBV) as a physiological parameter has been well recog-nized, especially in its relation to the intracranial pressure (ICP). Although various methods have been applied to measure CBV, several problems and difficulties still remain to be settled. In the present study, noninvasive monitoring of CBV on the cortical surface was done with organ reflec-tance spectrophotometry.

Through the cranial window, the cat brain was illuminated by the white light via optical fibers and reflected light was analized by spectrophoto-meter equipped with microcomputer and image-sensor (Sumitomo Elec. Co., Spectrum analyzer TS-200), which enables to estimate CBV on real time as the absorbance value at the isobestic point of the spectral curve of hemoglobin (Hb).

In order to ascertain the reliability and repro-ducibility, the change of CBV was examined by 5% & 10% CO2 inhalation, 5% O2 inhalation and bilateral jugular vein occlusion. A linear correla-tion was found between PaCO2 and Hb absorb-ance value on CO2 inhalation. By the bilateral ju-gular vein occlusion, Hb increased concomitantly with ICP, while cerebral blood flow (CBF) decrea-sed. On 5% O2 inhalation, absorbance spectral pat-tern of tissue Hb changed from that of oxy-Hb to deoxy-Hb without change of absorbance value at the isobestic point. Thus, the Hb absorbance va-lue obtained by this spectrophotometer was consi-dered to be reliable for the estimation of CBV on the cortical surface.

Using this, the change of CBV was examined on the drug-induced seizure and post-decompres-sion state after sustained intracranial hypertension.

After administration of bemegride in 3 cats, the CBV increased markedly and its change synch-ronized well with the epileptic burst of EEG in association with increase of CBF, ICP and blood pressure.

The change of CBV on the post-decompression state after sustained intracranial hypertension for 2 hours was also examined. In 6 of 8 cats, ICP gradually increased within 30 minutes after de-compression. Among them, continuous decrease of CBV was noted in 3 cats, in which large epidural hematomas were found. In the remaining 3 cats of no hematoma, CBV did not show any decrease, but even slight increase was noted. This finding well corresponded to the acute brain swelling where the increase of CBV might be the cause of increased ICP.

Thus, spectrophotometer used in this study enabled noninvasive, real time measurement of CBV on the cortical surface. This is quite useful to study the pathomechanism related to the cere-bral circulation and intracranial pressure. It will be also useful clinically to monitor CBV on the cortical surface during the operation.

Copyright © 1985, Igaku-Shoin Ltd. All rights reserved.


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