Two measures of ventilatory efficiency from preoperative cardiopulmonary exercise testing can risk stratify patients before oesophageal cancer surgery

<bold>Aim:</bold> To study the association between two measures of ventilatory efficiency (VE/VCO2-slope and end tidal CO2 [etCO2]) obtained at preoperative cardiopulmonary exercise testing (CPET) and major cardiopulmonary complications (MCPC) or death following oesophageal cancer surgery. <bold>Methods:</bold> Retrospective analysis of 43 patients (81% male) who performed preoperative CPET 2008-2023. EtCO2 was measured at the end of five minutes steady state (submaximal workload), and VE/VCO2-slope was defined up to the respiratory compensation point during ramp exercise. Main outcome was MCPC during hospitalization or death ≤30 days of surgery. Receiver operating characteristics (ROC) analysis was used to derive a threshold corresponding to 90% specificity for each measure. <bold>Results:</bold> The mean value (range) of etCO2 and VE/VCO2 slope in 29 operated patients were 4.6 (3.2-5.6) and 33 (25-45). The correlation between etCO2 and VE/VCO2 slope was strong (Pearson r=-0.88). Subjects with a VE/VCO2 slope ≥39 (n=7, 24%) had a complication frequency of 86% vs. 37% in the low-risk group, p=0.02. An etCO2 threshold of 4.1 kPa (30.8 mmHg) identified a high-risk group were 100% (4/4) suffered main outcome. The area under the curve was similar for a model using VE/VCO2 slope (0.70, 95% confidence interval (CI) 0.50-0.89) as compared to a model using etCO2 (0.69, 95% CI 0.49-0-88) to predict MCPC or death. <bold>Conclusions:</bold> Both VE/VCO2-slope and etCO2 during submaximal exercise at preoperative CPET was useful to risk stratify oesophagus cancer patients. As etCO2 can be measured with simple, hand-held equipment, it could be an option in situations when CPET is not available.