Prediction of Postoperative Complications: Ventilatory Efficiency and Rest End-tidal Carbon Dioxide.

Background: Cardiopulmonary exercise testing parameters including ventilatory efficiency (V _E /VCO ₂ slope) are used for risk assessment of lung resection candidates. However, many patients are unable or unwilling to undergo exercise. V _E /VCO ₂ slope is closely related to the partial pressure of end-tidal carbon dioxide (P _ET CO ₂ ). We hypothesized P _ET CO ₂ at rest predicts postoperative pulmonary complications.
Methods: Consecutive lung resection candidates were included in this prospective multicenter study. Postoperative respiratory complications were assessed from the first 30 postoperative days or from the hospital stay. Student t test or Mann-Whitney U test was used for comparison. Multivariate stepwise logistic regression analysis was used to analyze association with the development of postoperative pulmonary complications. The De Long test was used to compare area under the curve (AUC). Data are summarized as median (interquartile range).
Results: Three hundred fifty-three patients were analyzed, of which 59 (17%) developed postoperative pulmonary complications. P _ET CO ₂ at rest was significantly lower (27 [24-30] vs 29 [26-32] mm Hg; P < .01) and V _E /VCO ₂ slope during exercise significantly higher (35 [30-40] vs 29 [25-33]; P < .01) in patients who developed postoperative pulmonary complications. Both rest P _ET CO ₂ with odds ratio 0.90 (95% confidence interval [CI] 0.83-0.97); P = .01 and V _E /VCO ₂ slope with odds ratio 1.10 (95% CI 1.05-1.16); P < .01 were independently associated with postoperative pulmonary complications by multivariate stepwise logistic regression analysis. There was no significant difference between AUC of both models (rest P _ET CO ₂ : AUC = 0.79 (95% CI 0.74-0.85); V _E /VCO ₂ slope: AUC = 0.81 (95% CI 0.75-0.86); P = .48).
Conclusions: P _ET CO ₂ at rest has similar prognostic utility as V _E /VCO ₂ slope, suggesting rest P _ET CO ₂ may be used for postoperative pulmonary complications prediction in lung resection candidates.
(Copyright © 2023 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)