Is Ventilatory Equivalent for Carbon Dioxide (VE/VCO2) Slope the Key to Reduce Mortality in Patients Undergoing...

Cardiopulmonary exercise testing (CPET) definition of peak oxygen uptake (VO2 peak) is useful in detecting patients with an acceptable risk for pneumonectomy. Nevertheless, postoperative mortality remains high. CPET allows to define another promising parameter, the ventilatory equivalent for carbon dioxide (VE/VCO2 slope) that could further improve patients selection. We tested the hypothesis that VE/VCO2 slope values may identify patients with a prohibitive risk.

A retrospective analysis was performed on a cohort of patients who underwent pneumonectomy for lung cancer from March 2000 to March 2024. Postoperative morbidity and mortality were analysed according to VO2 peak and VE/CO2 slope values, and their risk was compared to patients who did not underwent preoperative CPET.

Out of 277 patients who underwent pneumonectomy, preoperative CPET was performed in 144 cases (52%). In this group, mortality and respiratory morbidity were 4% and 15%, respectively, compared to 6% and 14% in patients who did not undergo preoperative CPET. VE/VCO2 slope would have been effective in detecting patients with prohibitive risk. In fact, using a slope cutoff value of 35, postoperative respiratory complications and mortality were 33% and 17%, respectively, in patients with a slope above 35 compared to 13% and 2% in those having a slope lower than 35 (P <.05).

When VO2 peak suggests that pneumonectomy is feasible, values of VE/VCO2 slope deserve attention, as the risk becomes prohibitive when excessive CO2 retention is recorded during the test. The study suggested that a slope cut-off value of 35% may be useful to reduce postoperative adverse events.