Effects of hypoxia and normocarbia on cerebral blood flow and metabolism in conscious man.

Publisher Website
Google Scholar
Abstract
Cerebral blood flow (CBF) and carbohydrate metabolism were examined in 9 conscious male volunteers during a steady state of hypoxia produced by the inhalation of 6.9-7.5% O2, while hypocarbia was prevented by the addition of CO2 to the inspired gas. During hypoxia, PaO2 decreased from 89.4 to 34.6 torr, CBF increased from 45.0 to 77.1 ml/100 g/min, and cerebral vascular resistance decreased from 1.8 to 1.0 torr/ml/100 g/min. The increased CBF accompanying hypoxia did not completely compensate for the reduced PaO2, and a number of statistically significant metabolic alterations appeared. Cerebral glucose uptake increased from 4.48 to 5.73 mg/100 g/min, while cerebral lactate production increased more than 4-fold. During hypoxia, the fraction of glucose consumption that could be related to O2 uptake was lower than normal, a greater than normal proportion of glucose appeared as lactate, and cerebral O2 consumption did not change. Arterial and cerebral venous excess lactate did not appear during hypoxia in all subjects. Electroencephalographic changes occurred in only 2 of 7 subjects. Evaluation of the variables studied suggests that the most sensitive metabolic indices of cerebral hypoxia are changes in the rate of glucose uptake and in the relative amounts of glucose accounted for by lactate production and by O2 consumption.

This publication has 3 references indexed in Scilit: