Improved Risk Stratification Prior to Major Pulmonary Resection by Combining Peak Oxygen Uptake and Ventilatory Efficiency in a 9-Field Matrix

<h3>Background</h3> Cardiopulmonary exercise testing (CPET) has a pivotal role in preoperative evaluation of patients before lung cancer surgery. As surgical and perioperative practice and functional diagnostics continuously evolve, it may be time to reevaluate and refine the use of CPET in this setting. <h3>Research Question</h3> Can risk assessment with CPET before lung cancer surgery be improved by combining 2 established CPET variables (percent predicted peak oxygen uptake [Vo₂peak], and ventilatory efficiency, measured by minute ventilation [<mml:math><mml:mrow><mml:mi>V</mml:mi><mml:mo>˙</mml:mo><mml:mi>E</mml:mi></mml:mrow></mml:math>]/carbon dioxide elimination [Vco₂] slope) while using recently suggested optimal threshold values for these variables? <h3>Study Design and Methods</h3> Single-center, retrospective analysis of 208 patients with lung cancer who underwent preoperative CPET in 2008 to 2020. The main outcome was any major pulmonary complication (MPC) or death within 30 days of surgery. We combined previously suggested threshold values of percent predicted Vo₂peak and <mml:math><mml:mrow><mml:mi>V</mml:mi><mml:mo>˙</mml:mo><mml:mi>E</mml:mi></mml:mrow></mml:math>/Vco₂ slope, defined with a focus on high sensitivity and specificity. For each measure, patients were categorized into 3 groups based on these thresholds, yielding a proposed 9-field matrix for risk assessment. The frequency of complications between groups was compared using the χ² test. <h3>Results</h3> Overall, 29 patients (14%) suffered an MPC and 3 died. The frequency of complications differed between groups based on the 9-field matrix in patients who underwent lobectomy or pulmectomy (<i>P</i> < .001). No patient with both favorable percent predicted Vo₂peak and <mml:math><mml:mrow><mml:mi>V</mml:mi><mml:mo>˙</mml:mo><mml:mi>E</mml:mi></mml:mrow></mml:math>/Vco₂ slope values experienced MPC or death, whereas worsening values in both percent predicted Vo₂peak and <mml:math><mml:mrow><mml:mi>V</mml:mi><mml:mo>˙</mml:mo><mml:mi>E</mml:mi></mml:mrow></mml:math>/Vco₂ slope were associated with an increasing frequency of adverse outcomes. <h3>Interpretation</h3> The proposed 9-field matrix for risk assessment was able to demonstrate a synergistic effect between <mml:math><mml:mrow><mml:mi>V</mml:mi><mml:mo>˙</mml:mo><mml:mi>E</mml:mi></mml:mrow></mml:math>/Vco₂ slope and percent predicted Vo₂peak for identifying patients who suffered major pulmonary complications or death within 30 days of cancer lobectomy or pulmectomy. These results further improve and help nuance risk assessment in these patients.