Hemithorax Opacification & Large Volume Thoracentesis: A Novel Predictor of Re-Expansion Pulmonary Edema

Abstract

Introduction: Symptomatic pleural effusions are a common reason for hospital visits. Guidelines recommend draining < 1.5 L with large-volume thoracentesis (LVT) to avoid re-expansion pulmonary edema (REPE). Hemithorax opacification by pleural fluid on chest X-ray (CXR) has not been studied as predictor of REPE. We evaluated the incidence of REPE using hemithorax opacification on CXR. Methods: We reviewed LVTs with preand post-procedural chest CXR from 2008 to 2019 at a tertiary urban hospital. Image J software was used to calculate the percentage of hemithorax opacification before and after drainage. CXRs were independently reviewed by a radiologist and interventional pulmonologist-both blinded to clinical data. Clinical REPE was separately according to clinical signs and symptoms. Results: 198 LVTs with CXRs were reviewed. Median volume drained was 1.8 L (IQR 1.6 L-2.0 L) and median percent opacification drained was 26% (IQR 13-40%): 11.1% of cases drained > 50% opacification, and 17.7% had complete drainage. 177 post-procedural CXRs were amenable for evaluation and 20.3% had evidence of radiographic REPE. In those with radiographic REPE, 2.5% had clinical REPE. Multivariate regression analysis demonstrated that draining > 50% of the opacified hemithorax was associated with radiographic REPE (OR 3.51, 95% CI 1.09-11.26, p = 0.035) and clinical REPE (OR 11.22, 95% CI 1.67-75.16, p = 0.013). Conclusion: Radiographic REPE was relatively common, but often without symptoms. The reduction of > 50% of hemithorax opacification is a novel predictor of REPE. We suggest individualizing limitations of fluid removal according to hemithorax opacification and clinical scenario rather than an arbitrary cutoff of 1.5 L.