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

by Andrej Mazur, Kristian Brat, Pavel Homolka, Zdenek Merta, Michal Svoboda, Monika Bratova, Vladimir Sramek, Lyle J. Olson, Ivan Cundrle

Introduction

Ventilatory efficiency (V_E/VCO₂ slope) has been shown superior to peak oxygen consumption (VO₂) for prediction of post-operative pulmonary complications in patients undergoing thoracotomy. V_E/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, V_E/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 V_E/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

V_E/VCO₂ slope is superior to peak VO₂ for prediction of post-operative cardiovascular complications in lung resection candidates.