Prolonged oxygen debt after abdominal aortic surgery.

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 (VO2), carbon dioxide production (VCO2), 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, VO2 and VCO2 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, VO2 decreased with the postoperative increase of body temperature; whereas in the CABG patients, VO2 slightly increased.

CONCLUSIONS

The high VO2 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.