Stroke, Vol 25, 403-407, Copyright © 1994 by American Heart Association
H Endoh and K Shimoji
BACKGROUND AND PURPOSE: We evaluated the utility of blood flow velocity
measurements by transcranial Doppler ultrasonography as a tool to
indirectly measure cerebral perfusion during cardiopulmonary bypass.
METHODS: We simultaneously measured blood flow velocity in the middle
cerebral artery and physiological variables in 18 patients undergoing
cardiac surgery under hypothermic cardiopulmonary bypass in which pH and
PaCO2 were managed with the alpha-stat acid-base strategy. We expressed
blood flow velocity as a relative value of control obtained under
normothermia and normocarbia before bypass. We also developed an original
index, modified cerebral metabolic rate for oxygen, to estimate cerebral
metabolic rate for oxygen. RESULTS: Relative velocity was significantly (P
< .01) reduced during stable aortic cross-clamp compared with before
bypass and was significantly (P < .01) increased during rewarming
compared with at aortic cross-clamp. Modified cerebral metabolic rate for
oxygen significantly correlated with nasopharyngeal temperature during
cooling, aortic cross-clamp, and rewarming (r = .756, P < .0001; r = .4,
P < .01; r = .725, P < .0005, respectively). Calculated temperature
coefficient for modified cerebral metabolic rate of oxygen was 2.7 +/- 1.4
(mean +/- SD, n = 10) during cooling. Only nasopharyngeal temperature and
PaCO2 were significant determinants of relative velocity during aortic
cross-clamp. CONCLUSIONS: We can monitor cerebral perfusion and metabolism
by measurements of relative velocity and modified cerebral metabolic rate
for oxygen during hypothermic cardiopulmonary bypass.
ARTICLES
Changes in blood flow velocity in the middle cerebral artery during nonpulsatile hypothermic cardiopulmonary bypass
Department of Anesthesiology, Niigata City General Hospital, Japan.
This article has been cited by other articles:
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L. J. Saidman Anesthesiology JAMA, June 19, 1996; 275(23): 1795 - 1797. [Abstract] [PDF] |
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