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The reason for cardiac output reduction after aortic cross-clamping
S Gelman1, H McDowell, P D Varner
1Department of Anesthesiology, University of Alabama at Birmingham 35294.
American Journal of Surgery
|April 1, 1988
Summary
Cardiac output decrease during aortic cross-clamping is linked to reduced tissue oxygen use, not heart function decline. Nitroglycerin did not alter oxygen consumption but improved oxygen delivery.
Area of Science:
- Cardiovascular Physiology
- Surgical Anesthesia
Background:
- Infrarenal aortic cross-clamping can decrease cardiac output.
- The exact cause of this decrease is debated, with theories including myocardial performance changes and altered tissue oxygen consumption.
Purpose of the Study:
- To test the hypothesis that decreased cardiac output during aortic cross-clamping is due to reduced tissue oxygen consumption (cross-clamp-adapted oxygen consumption).
- To evaluate the effect of nitroglycerin on cardiac output and oxygen metabolism during this procedure.
Main Methods:
- Twenty-two patients undergoing aortic aneurysm repair were randomized into two groups.
- Group 1 received nitroglycerin infusion during aortic cross-clamping; Group 2 did not.
- Cardiac output, oxygen consumption, mixed venous oxygen content, and arteriovenous oxygen difference were measured.
Main Results:
- Oxygen consumption decreased by 40-42% in both groups during cross-clamping.
- Cardiac output decreased by 17% in the control group but remained stable in the nitroglycerin group.
- Mixed venous oxygen content increased in both groups, with a further increase in the nitroglycerin group.
Conclusions:
- The findings support the hypothesis that reduced cardiac output during aortic cross-clamping is related to decreased tissue oxygen consumption, not impaired myocardial function.
- Nitroglycerin infusion during aortic cross-clamping improved oxygen delivery without increasing oxygen utilization.