Background: Studies of preoperative cardiopulmonary exercise testing (CPET) have shown that a reduced oxygen uptake at anaerobic threshold (AT) and elevated ventilatory equivalent for carbon dioxide (VE/VCO(2)) were associated with reduced short- and medium-term survival after major surgery. The aim of this study was to determine the relative values of these, and also clinical risk factors, in identifying patients at risk of death after major intra-abdominal, non-vascular surgery.
Methods: Patients aged >55 yr, undergoing elective colorectal resection, radical nephrectomy, or cystectomy between June 2004 and May 2009 had CPET during their routine pre-assessment clinic visit. We performed a retrospective analysis of known clinical risk factors and data from CPET to assess their relationship to all-cause mortality after surgery.
Results: Eight hundred and forty-seven patients underwent surgery, of whom 18 (2.1%) died. A clinical history of ischaemic heart disease (RR 3.1, 95% CI 1.3-7.7), a VE/VCO(2) >34 (RR 4.6, 95% CI 1.4-14.8), and an AT < or =10.9 ml kg(-1) min(-1) (RR 6.8, 95% CI 1.6-29.5) were all significant predictors of all-cause hospital and 90 day mortality. The effect of reduced AT was most pronounced in patients with no history of cardiac risk factors (RR 10.0, 95% CI 1.7-61.0).
Conclusions: The routine measurement of AT and VE/VCO(2) using CPET for patients undergoing high-risk surgery can accurately identify the majority of high-risk patients, while the use of clinical risk factors alone will only identify a relatively small proportion of at-risk patients.