Prediction of Total Lung Capacity and Residual Volume Eligibilities for Endobronchial Valve Treatment Using Measurements by the Helium Dilution Technique, CT ‐Based Lung Volume Analysis, and Spirometry

ABSTRACT Background and Objective Endobronchial valve (EBV) placement reduces hyperinflation in patients with severe COPD. Eligibility criteria of EBV include total lung capacity (TLC pleth ) ≥ 100% and residual volume (RV pleth ) ≥ 175% by body plethysmography. In this study, we evaluated the performance of alternative modalities for predicting EBV criteria in clinical settings where body plethysmography is unavailable. Methods This is a single centre observational study. We recruited 41 patients with COPD at St. Marianna University Hospital. The participants underwent spirometry for VC, FVC, and FEV 1 , body plethysmography for TLC pleth and RV pleth , and the helium dilution technique for TLC He and RV He as well as CT scanning at full inspiration and expiration to calculate air volume (AV) and total lung volume (TLV), which includes both air and tissue volumes. We also estimated TLV pleth and RV pleth by using previously proposed formulas from the University of Groningen (TLC Groningen and RV Groningen ) and from the University of Pittsburgh (RV Pittsburgh ). Results The alternative measurements, that is, TLC He , AV inspiratory CT , TLV inspiratory CT , TLC Groningen , RV He , AV inspiratory CT – VC, AV expiratory CT , TLV inspiratory CT – VC, TLV expiratory CT , RV Groningen , and RV Pittsburgh , correlated well with TLC pleth and RV pleth . Receiver operating characteristic analysis to predict TLC pleth ≥ 100%, RV pleth ≥ 175%, or RV pleth ≥ 150% by these alternatives yielded high area under the curve (AUC) values around 0.924–0.937. We also determined the threshold values for sensitivity = 100% (Rule‐out threshold) and specificity = 100% (Rule‐in threshold) to predict TLC pleth ≥ 100%, RV pleth ≥ 175%, or RV pleth ≥ 150%. Conclusion Our findings indicate that, when body plethysmography is not feasible, these measurements may help identify patients likely or unlikely to meet plethysmography‐defined EBV eligibility criteria.