Cerebral blood flow reactivity to changes in carbon dioxide calculated using end-tidal versus arterial tensions.
We retrospectively examined arerial and end-tidal estimations of CO2 tension used to calculate cerebrovascular reactivity in 68 anesthetized patients. CBF was measured using the intravenous 133Xe technique at mean +/- SD PaCO2 values of 28.2 +/- 5.2 and 38.8 +/- 4.8 mm Hg. The correlation between all PaCO2 and end-tidal PCO2 (PetCO2) values was y = 0.85x - 0.49 (r = 0.93, p = 0.0001). There was a moderate correlation between age and the difference between PaCO2 and PetCO2 (y = 0.11x + 0.79; r = 0.73, p = 0.0001). Cerebrovascular reactivity to changes in CO2 (ml 100 g-1 min-1 mm Hg-1) was similar (p = 0.358) when calculated by using either PaCO2 (1.9 +/- 0.8) or PetCO2 (1.8 +/- 0.8) and highly correlated (y = 0.86x + 0.23; r = 0.91, p = 0.0001). The CBF response to changes in CO2 tension can be reliably estimated from noninvasive measurement of PetCO2.
Department of Anesthesiology, Columbia University College of Physicians and Surgeons, New York, New York 10032.
W L
WL
Young
I
I
Prohovnik
E
E
Ornstein
N
N
Ostapkovich
R S
RS
Matteo
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D001158:Arteries; D002245:Carbon Dioxide / Q000097:blood*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D010313:Partial Pressure; D012119:Respiration; D012189:Retrospective Studies; D013990:Tidal Volume
D002245:Carbon Dioxide