Increased minute ventilation-to-carbon dioxide slope during cardiopulmonary exercise test is associated with poor postoperative outcome following lung cancer resection
Amr Rushwan, Demetrios Stefanou, Javeria Tariq, Polivious Drosos, Nilanjan Chaudhuri, Richard Milton, Peter Tcherveniakov, Kostas Papagiannopoulos, Alessandro Brunelli
Abstract
OBJECTIVES: Ventilatory efficiency [minute ventilation-to-carbon dioxide output slope (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. 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: A total of 552 patients were included (374 lobectomies, 81 segmentectomies, 55 pneumonectomies and 42 wedge resections). Seventy-four percent were minimally invasive procedures. Cardiopulmonary morbidity was 32%, in-hospital/30-day mortality 6.9% and 90-day mortality 8.9%. A total of 137 patients (25%) had a slope of >40. These patients were older (72 vs 70 years, P = 0.012), had more frequently coronary artery disease (17% vs 10%, P = 0.028), lower carbon monoxide lung diffusion capacity (57% vs 68%, P < 0.001), lower body mass index (25.4 vs 27.0 kg/m2, P = 0.001) and lower peak VO2 (14.9 vs 17.0 ml/kg/min, P < 0.001) than those with a lower slope. The cardiopulmonary morbidity among patients with a slope of >40 was 40% vs 29% in those with lower slope (P = 0.019). Ninety-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.