The effect of temperature on cerebral metabolism and blood flow in adults during cardiopulmonary bypass.

Published

Journal Article

The effect of temperature on cerebral blood flow and metabolism was studied in 41 adult patients scheduled for operations requiring cardiopulmonary bypass. Plasma levels of midazolam and fentanyl were kept constant by a pharmacokinetic model-driven infusion system. Cerebral blood flow was measured by xenon 133 clearance (initial slope index) methods. Cerebral blood flow determinations were made at 27 degrees C (hypothermia) and 37 degrees C (normothermia) at constant cardiopulmonary bypass pump flows of 2 L/min/m2. Blood gas management was conducted to maintain arterial carbon dioxide tension (not corrected for temperature) 35 to 40 mm Hg and arterial oxygen tension of 150 to 250 mm Hg. Blood gas samples were taken from the radial artery and the jugular bulb. With decreased temperature there was a significant (p less than 0.0001) decrease in the arterial venous-oxygen content difference, suggesting brain flow in excess of metabolic need. For each patient, the cerebral metabolic rate of oxygen consumption at 37 degrees C and 27 degrees C was calculated from the two measured points at normothermia and hypothermia with the use of a linear relationship between the logarithm of cerebral metabolic rate of oxygen consumption and temperature. The temperature coefficient was then computed as the ratio of cerebral metabolic rate of oxygen consumption at 37 degrees C to that at 27 degrees C. The median temperature coefficient for man on nonpulsatile cardiopulmonary bypass is 2.8. Thus reducing the temperature from 37 degrees to 27 degrees C reduces cerebral metabolic rate of oxygen consumption by 64%.

Full Text

Duke Authors

Cited Authors

  • Croughwell, N; Smith, LR; Quill, T; Newman, M; Greeley, W; Kern, F; Lu, J; Reves, JG

Published Date

  • March 1992

Published In

Volume / Issue

  • 103 / 3

Start / End Page

  • 549 - 554

PubMed ID

  • 1545554

Pubmed Central ID

  • 1545554

Electronic International Standard Serial Number (EISSN)

  • 1097-685X

International Standard Serial Number (ISSN)

  • 0022-5223

Language

  • eng