Cardiopulmonary exercise variables are associated with postoperative morbidity after major colonic surgery: a prospective blinded observational study

Abstract

Background: Postoperative complications are associated with reduced fitness. Cardiopulmonary exercise testing (CPET) has been used in risk stratification. We investigated the relationship between preoperative CPET and in-hospital morbidity in major colonic surgery.

Methods: We prospectively studied 198 patients undergoing major colonic surgery (excluding neoadjuvant cancer therapy), performing preoperative CPET (reported blind to clinical state), and recording morbidity (assessed blind to CPET), postoperative outcome, and length of stay.

Results: Of 198 patients, 62 were excluded: 11 had emergency surgery, 25 had no surgery, 23 had incomplete data, and three were unable to perform CPET. One hundred and thirty-six (89 males, 47 females) were available for analysis. The median age was 71 [inter-quartile range (IQR) 62-77] yr. Sixty-five patients (48%) had a complication at day 5 after operation. Measurements significantly lower in patients with complications than those without were O2 uptake (VO₂) at estimated lactate threshold (θ(L)) [median 9.9 (IQR 8.3-12.7) vs 11.2 (9.5-14.2) ml kg(-1) min(-1), P<0.01], VO₂ at peak [15.2 (12.6-18.1) vs 17.2 (13.7-22.5) ml kg(-1) min(-1), P=0.01], and ventilatory equivalent for CO2 (V(E)/VCO₂) at θ(L) [31.3 (28.0-34.8) vs 33.9 (30.0-39.1), P<0.01]. A final multivariable logistic regression model contained VO₂ at θ(L) {one-point change odds ratio (OR) 0.77 [95% confidence interval (CI) 0.66-0.89], P<0.0005; two-point change OR 0.61 (0.46-0.81) and gender [OR 4.42 (1.78-9.88), P=0.001]}, and was reasonably able to discriminate those with and without complications (AUC 0.71, CI 0.62-0.80, 68% sensitivity, 65% specificity).

Conclusions: CPET variables are associated with postoperative morbidity. A multivariable model with VO₂ at θ(L) and gender discriminates those with complications after colonic surgery.

Keywords: anaerobic threshold; cardiopulmonary exercise test; colorectal surgery; morbidity; postoperative complications.