Increased minute ventilation to carbon dioxide slope during cardiopulmonary exercise test is associated with poor postoperative outcome following lung cancer resection

Abstract

Abstract OBJECTIVES Ventilatory efficiency (VE/VCO2 slope) can be measured at sub-maximal workload during cardiopulmonary exercise test. The aim of this study is to assess the association between VE/VCO2 slope and outcome after lung cancer resections. METHODS Retrospective, single centre analysis on all patients undergoing lung resection for cancer (April 2014-August 2022) and with a preoperative cardiopulmonary exercise test (CPET). VE/VCO2 slope >40 was chosen as high-risk threshold. Logistic regression analysis was used to test the association of VE/VCO2 slope and several patient- and surgery-related factors with 90-day mortality. RESULTS 552 patients were included (374 lobectomies, 81 segmentectomies, 55 pneumonectomies and 42 wedge resections). 74% were minimally invasive procedures. Cardiopulmonary morbidity was 32%, in-hospital/30-day mortality 6.9% and 90-day mortality 8.9%. 137 patients (25%) had a slope > 40. These patients were older (72 years vs 70, p = 0.012), had more frequently coronary artery disease (17% vs.10%,p = 0.028), lower DLCO (57% vs.68%,p < 0.001), lower BMI (25.4 kg/m2 vs.27.0 kg/m2, p = 0.001) and lower peak VO2 (14.9 mL/kg/min vs 17.0 mL/kg/min, p < 0.001) than those with a lower slope. The cardiopulmonary morbidity amongst patients with a slope >40 was 40% vs.29% in those with lower slope(p = 0.019). 90-day mortality was 15% vs.6.7% (p = 0.002). The 90-day mortality of elderly patients with slope > 40 was 21% vs.7.8%(p = 0.001). After adjusting for peak VO2 value, extent of operation and other patient-related variables in a logistic regression analysis, VE/VCO2 slope retained a significant association with 90-day mortality. CONCLUSIONS VE/VCO2 slope was strongly associated with morbidity and mortality following lung resection and should be included in the functional algorithm to assess fitness for surgery.