title: 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.
authors: Colorectal Surgery Research Group, 3rd Floor Clinical Sciences Building, Aintree University Hospitals NHS Foundation Trust, Lower Lane, Liverpool L9 7AL, UK.
authors: M A
authors: MA
authors: West
authors: D
authors: D
authors: Lythgoe
authors: C P
authors: CP
authors: Barben
authors: L
authors: L
authors: Noble
authors: G J
authors: GJ
authors: Kemp
authors: S
authors: S
authors: Jack
authors: M P W
authors: MP
authors: Grocott
mesh_terms: D000368:Aged; D015308:Anaerobic Threshold / Q000502:physiology; D003106:Colon / Q000601:surgery*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D011183:Postoperative Complications; D011300:Preoperative Care / Q000379:methods*; D011379:Prognosis; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods; D016037:Single-Blind Method
keywords: anaerobic threshold; cardiopulmonary exercise test; colorectal surgery; morbidity; postoperative complications