Cardiopulmonary exercise testing predicts postoperative outcome in patients undergoing gastric bypass surgery

Abstract

Background For several types of non-cardiac surgery, the cardiopulmonary exercise testing (CPET)-derived variables anaerobic threshold (AT), peak oxygen consumption (peak), and ventilatory equivalent for CO2 () are predictive of increased postoperative risk: less physically fit patients having a greater risk of adverse outcome. We investigated this relationship in patients undergoing gastric bypass surgery.Methods All patients (<190 kg) who were referred for CPET and underwent elective gastric bypass surgery at the Whittington Hospital NHS Trust between September 1, 2009, and February 25, 2011, were included in the study (n121). Fifteen patients did not complete CPET. CPET variables (peak, AT, and) were derived for 106 patients. The primary outcome variables were day 5 morbidity and hospital length of stay (LOS). The independent t-test and Fisher's exact test were used to test for differences between surgical outcome groups. The predictive capacity of CPET markers was determined using receiver operating characteristic (ROC) curves.Results The AT was lower in patients with postoperative complications than in those without [9.9 (1.5) vs 11.1 (1.7) ml kg-1 min-1, P0.049] and in patients with a LOS>3 days compared with LOS≤3 days [10.4 (1.4) vs 11.3 (1.8) ml kg-1 min-1, P0.023]. ROC curve analysis identified AT as a significant predictor of LOS>3 days (AUC 0.640, P0.030). The peak and were not associated with postoperative outcome.Conclusions AT, determined using CPET, predicts LOS after gastric bypass surgery. © The Author [2012]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved.