Ventilatory efficiency in combination with peak oxygen uptake improves risk stratification in patients undergoing lobectomy

JTCVS Open. 2022 Jul 3;11:317-326. doi: 10.1016/j.xjon.2022.06.018. eCollection 2022 Sep.

Abstract

Objective: We aimed to evaluate whether or not using the slope of the increase in minute ventilation in relation to carbon dioxide (VE/VCo2-slope), with a cutoff value of 35, could improve risk stratification for major pulmonary complications or death following lobectomy in lung cancer patients at moderate risk (Vo2peak = 10-20 mL/kg/min).

Methods: Single center, retrospective analysis of 146 patients with lung cancer who underwent lobectomy and preoperative cardiopulmonary exercise testing in 2008-2020. The main outcome was any major pulmonary complication or death within 30 days of surgery. Patients were categorized based on their preoperative cardiopulmonary exercise testing as: low-risk group, peak oxygen uptake >20 mL/kg/min; low-moderate risk, peak oxygen uptake 10 to 20 mL/kg/min and VE/VCo2-slope <35; and moderate-high risk, peak oxygen uptake 10 to 20 mL/kg/min and VE/VCo2-slope ≥35. The frequency of complications between groups was compared using χ2 test. Logistic regression was used to calculate the odds ratio with 95% CI for the main outcome based on the cardiopulmonary exercise testing group.

Results: Overall, 25 patients (17%) experienced a major pulmonary complication or died (2 deaths). The frequency of complications differed between the cardiopulmonary exercise testing groups: 29%, 13%, and 8% in the moderate-high, low-moderate, and low-risk group, respectively (P = .023). Using the low-risk group as reference, the adjusted odds ratio for the low-moderate risk group was 3.44 (95% CI, 0.66-17.90), whereas the odds ratio for the moderate-high risk group was 8.87 (95% CI, 1.86-42.39).

Conclusions: Using the VE/VCo2-slope with a cutoff value of 35 improved risk stratification for major pulmonary complications following lobectomy in lung cancer patients with moderate risk based on a peak oxygen uptake of 10 to 20 mL/kg/min. This suggests that the VE/VCo2-slope can be used for preoperative risk evaluation in lung cancer lobectomy.

Keywords: CPET, cardiopulmonary exercise testing; DLCOc, carbon monoxide lung diffusion capacity corrected for hemoglobin; EqCo2 nadir, the lowest value (nadir) of the ventilation/VCO2 ratio during exercise; FEV1, forced expiratory volume in 1 second; MCPC, major cardiopulmonary complications; MITS, minimally invasive thoracic surgery; MPC, major pulmonary complications; VCo2, carbon dioxide elimination; VE, minute ventilation; VE/VCo2-slope, the slope of the increase in minute ventilation in relation to carbon dioxide output; Vo2peak, peak oxygen uptake; cardiopulmonary exercise testing; guidelines; lung cancer; peak oxygen uptake; risk stratification; ventilatory efficiency.