Cardiopulmonary exercise testing predicts postoperative outcome in patients undergoing gastric bypass surgery.
BACKGROUND
For several types of non-cardiac surgery, the cardiopulmonary exercise testing (CPET)-derived variables anaerobic threshold (AT), peak oxygen consumption (VO2 peak), and ventilatory equivalent for CO(2) (VE/VCO2 ) 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 (n=121). Fifteen patients did not complete CPET. CPET variables (VO2 peak, AT, and VE/VCO2 ) 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), P=0.049] 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), P=0.023]. ROC curve analysis identified AT as a significant predictor of LOS>3 days (AUC 0.640, P=0.030). The VO2 peak and VE/VCO2 were not associated with postoperative outcome.


CONCLUSIONS
AT, determined using CPET, predicts LOS after gastric bypass surgery.
Portex Unit, UCL Institute of Child Health, London, UK. p.hennis@ucl.ac.uk
P J
PJ
Hennis
P M
PM
Meale
R A
RA
Hurst
A F
AF
O'Doherty
J
J
Otto
M
M
Kuper
N
N
Harper
P A
PA
Sufi
D
D
Heath
H E
HE
Montgomery
M P W
MP
Grocott
D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D019540:Area Under Curve; D001835:Body Weight / Q000502:physiology; D005080:Exercise Test / Q000379:methods*; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D007902:Length of Stay; D008297:Male; D010359:Patient Readmission; D010809:Physical Fitness; D011183:Postoperative Complications / Q000453:epidemiology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D016896:Treatment Outcome