Stroke, Vol 21, 278-282, Copyright © 1990 by American Heart Association
WL Young, I Prohovnik, JW Correll and N Ostapkovich
Regional cerebral blood flow studies with xenon-133 are useful in the
functional assessment of cerebrovascular diseases. Conventional models for
cerebral blood flow calculation employ 11 minutes of data collection.
However, in many circumstances it is not possible to maintain steady-state
physiologic conditions for 11 minutes. We compared a monocompartmental
model that requires only 3 minutes of data collection with the
bicompartmental model that requires 11 minutes of data collection. The
correlation between the absolute values for global cerebral blood flow
(initial slope index, intravenous method) in 72 anesthetized patients was r
= 0.88; for 54 awake patients inhaling xenon-133, the correlation was r =
0.77. Cerebral blood flow was determined with intravenous xenon-133 at
baseline and during a CO2 challenge in 50 patients during cerebrovascular
surgery under general anesthesia. Reactivity to a 10-mm Hg rise in PaCO2
was calculated in absolute terms and as a percentage change from baseline
using both the 3-minute and the 11-minute models. The correlation of CO2
reactivity calculated with the two models was r = 0.9 for the absolute
values and r = 0.8 for the relative change. Cerebral blood flow calculated
with the two models correlated well in both awake and anesthetized
patients. In addition, there was a good correlation between CO2 reactivity
calculated with the two models. In situations in which physiologic
conditions cannot be held stable for 11 minutes, the 3-minute initial slope
index may be used to quantitatively assess cerebrovascular reserve with a
CO2 challenge.
ARTICLES
Three-minute blood flow index for assessment of cerebrovascular reserve
Department of Anesthesiology, Columbia University College of Physicians and Surgeons, New York, New York.
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