Abdominal aortic cross-clamping. Metabolic and hemodynamic consequences.

We address the question of whether an oxygen debt develops during a period of abdominal aortic cross-clamping that may explain observed hemodynamic changes. Group 1 received morphine sulfate (1 mg/kg) during induction of anesthesia. Group 2 received same dose of morphine sulfate. Group 3 received 4 mg/kg of morphine sulfate. We measured the oxygen consumption (VO2) and the carbon dioxide production levels (VCO2), as well as hemodynamic and biochemical parameters. In groups 1 and 3, VO2 and VCO2 decreased 10% to 13% following abdominal aortic cross-clamping compared with values measured before cross-clamping. In group 2, VO2 and VCO2 decreased 3% and 7%, respectively. On unclamping, the greatest increase in VO2 was observed in group 3 (26%), while in groups 1 and 2, VO2 rose 18% and 5%, respectively. In all three groups, metabolic changes were not paralleled by hemodynamic or temperature changes. Results indicate that oxygen debt developed during abdominal aortic cross-clamping, but this has no effect on hemodynamic changes seen after unclamping. Higher dosage of narcotic administered during anesthetic induction did not temper increase in metabolic rate observed after unclamping.