Prolonged oxygen debt after abdominal aortic surgery

Abstract

Objective: The aim of the study was to investigate whether oxygen consumption and carbon dioxide production changed in the early postoperative period in the same manner in patients who underwent coronary artery bypass graft (CABG) surgery or abdominal aortic surgery (AAS). Design: Prospective clinical study. Setting: Single community hospital. Participants: Twenty-four patients (ASA II to III) who underwent elective abdominal aortic surgery and 49 patients (NYHA II, III) who underwent elective CABG surgery. Interventions: In the ICU, oxygen consumption (Vo 2), carbon dioxide production (VCO 2), and respiratory quotient (RQ) were continuously monitored with an indirect calorimetric device. Hemodynamic and metabolic parameters were measured during the first 3 hours. Measurements and Main Results: In the early postoperative course, Vo 2 and VCO 2 in the AAS group were significantly higher ( p < 0.001), and the RQ was significantly lower during the first 90 minutes ( p < 0.001). In the AAS patients, Vo 2 decreased with the postoperative increase of body temperature; whereas in the CABG patients, Vo 2 slightly increased. Conclusions: The high Vo 2 in the AAS patients observed during the early postoperative course can be explained by an oxygen debt that occurred as a result of clamping the aorta. It was presumed that the repayment of the debt was delayed and extended to the ICU stay because of thermoregulatory vasoconstriction. Abnormally low RQ values are probably a clue to repayment of an oxygen debt.