Ventilatory efficiency is superior to peak oxygen uptake for prediction of lung resection cardiovascular complications

INTRODUCTION: Ventilatory efficiency (V(E)/VCO(2) slope) has been shown superior to peak oxygen consumption (VO(2)) for prediction of post-operative pulmonary complications in patients undergoing thoracotomy. V(E)/VCO(2) slope is determined by ventilatory drive and ventilation/perfusion mismatch whereas VO(2) is related to cardiac output and arteriovenous oxygen difference. We hypothesized pre-operative VO(2) 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 VO(2) 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, V(E)/VCO(2) 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 V(E)/VCO(2) slope [OR = 1.06; 95%CI (1.01–1.11); P = 0.01; AUC = 0.74], but not peak VO(2) to be independently associated with post-operative cardiovascular complications. CONCLUSION: V(E)/VCO(2) slope is superior to peak VO(2) for prediction of post-operative cardiovascular complications in lung resection candidates.