Ventilatory efficiency for CO2 and rest end-tidal CO2 are similar predictors of post-operative pulmonary complications

Abstract

<b>Aims and Objectives:</b> Cardiopulmonary exercise testing (CPET) is used for preoperative risk assessment in lung resection candidates. Ventilatory efficiency for carbon dioxide (VE/VCO2) slope was proposed better predictor of postoperative pulmonary complications (PPC) than maximal oxygen uptake (peakVO2). However, a substantial number of patients are unable to undergo CPET. VE/VCO2 is closely related to the partial pressure of end-tidal carbon dioxide (PETCO2). We hypothesized PETCO2 at rest may predict PPC. <b>Methods:</b> Consecutive lung resection candidates able to undergo CPET were included in this prospective multicenter study. PPC were assessed from the first 30 post-operative days. Student t-test or Mann-Whitney U test was used for comparison. Multivariate logistic regression analysis was used to analyze association of respiratory parameters with the development of PPC. De Long test was used to compare AUCs. Data are shown as median (IQR). p values &lt;0.05 were considered significant. <b>Results:</b> 353&nbsp;subjects were included, of these 59 (17%) developed PPC. PETCO2 at rest was significantly lower (27 vs. 29 mmHg; p&lt;0.01) and VE/VCO2 slope significantly higher (35 vs. 29; p&lt;0.01) in patients who developed PPC compared to those who did not. In the multivariate analysis, both rest PETCO2 with OR=0.90 (95%CI 0.83; 0.97), p=0.01 and VE/VCO2 slope with OR=1.10 (95%CI 1.05; 1.16), p&lt;0.01 were independently associated with PPC. There was no difference between AUCs of both parameters (rest PETCO2: 0.79; VE/VCO2 slope 0.81; p=0.48). <b>Conclusion:</b> PETCO2 at rest had similar prognostic power as VE/VCO2 slope, suggesting rest PETCO2 may be used as a surrogate of VE/VCO2 slope for PPC prediction.