Ventilatory efficiency is superior to peak oxygen uptake for prediction of lung resection cardiovascular complications
Andrej Mazur, Kristián Brat, Pavel Homolka, Zdeněk Merta, Michal Svoboda, Monika Bratová, Vladimír Šrámek, Lyle J. Olson, Ivan Čundrle
Abstract
INTRODUCTION: Ventilatory efficiency (VE/VCO2 slope) has been shown superior to peak oxygen consumption (VO2) for prediction of post-operative pulmonary complications in patients undergoing thoracotomy. VE/VCO2 slope is determined by ventilatory drive and ventilation/perfusion mismatch whereas VO2 is related to cardiac output and arteriovenous oxygen difference. We hypothesized pre-operative VO2 predicts post-operative cardiovascular complications in patients undergoing lung resection. METHODS: Lung resection candidates from a published study were evaluated by post-hoc analysis. All of the patients underwent preoperative cardiopulmonary exercise testing. Post-operative cardiovascular complications were assessed during the first 30 post-operative days or hospital stay. One-way analysis of variance or the Kruskal-Wallis test, and multivariate logistic regression were used for statistical analysis and data summarized as median (IQR). RESULTS: Of 353 subjects, 30 (9%) developed pulmonary complications only (excluded from further analysis), while 78 subjects (22%) developed cardiovascular complications and were divided into two groups for analysis: cardiovascular only (n = 49) and cardiovascular with pulmonary complications (n = 29). Compared to patients without complications (n = 245), peak VO2 was significantly lower in the cardiovascular with pulmonary complications group [19.9 ml/kg/min (16.5-25) vs. 16.3 ml/kg/min (15-20.3); P<0.01] but not in the cardiovascular only complications group [19.9 ml/kg/min (16.5-25) vs 19.0 ml/kg/min (16-23.1); P = 0.18]. In contrast, VE/VCO2 slope was significantly higher in both cardiovascular only [29 (25-33) vs. 31 (27-37); P = 0.05] and cardiovascular with pulmonary complication groups [29 (25-33) vs. 37 (34-42); P<0.01)]. Logistic regression analysis showed VE/VCO2 slope [OR = 1.06; 95%CI (1.01-1.11); P = 0.01; AUC = 0.74], but not peak VO2 to be independently associated with post-operative cardiovascular complications. CONCLUSION: VE/VCO2 slope is superior to peak VO2 for prediction of post-operative cardiovascular complications in lung resection candidates.