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.
Young
W L
WL
Department of Anesthesiology, Columbia University College of Physicians and Surgeons, New York, New York 10032.
Prohovnik
I
I
Ornstein
E
E
Ostapkovich
N
N
Matteo
R S
RS
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