Impact of large-volume thoracentesis on transpulmonary thermodilution-derived extravascular lung water in medical intensive care unit patients

PURPOSE: The purpose of this study was to investigate the impact of large-volume thoracentesis (>1000 mL) on transpulmonary thermodilution (TPTD)-derived cardiopulmonary parameters with special regard to extravascular lung water index (EVLWI).

MATERIALS AND METHODS: Retrospective analysis of a prospectively maintained database including TPTD measurements of patients treated in a medical intensive care unit of a German university hospital between January 2009 and September 2010. Data of 17 patients treated with large-volume thoracentesis were analyzed.

RESULTS: A median of 1350 (25%-75% interquartile range [IQR], 1200-1590) mL of pleural fluid was removed. Extravascular lung water index was statistically significantly higher after thoracentesis compared with baseline (9.0 [IQR, 8.0-13.0] vs 8.0 [IQR, 7.0-13.0] mL/kg) (P = .039). Pulmonary vascular permeability index (PVPI) also increased significantly after thoracentesis (1.7 [IQR, 1.3-2.4] vs 1.4 [IQR, 1.1-2.1]) (P = .019). When determined 2 and 6 hours after thoracentesis, EVLWI and PVPI even further increased. Six hours after removal of pleural fluid, we observed a median EVLWI of 11.0 (IQR, 8.0-15.0) mL/kg (P = .048 compared with baseline) and a median PVPI of 2.0 (IQR, 1.5-2.7) (P = .040 compared with baseline).

CONCLUSIONS: Large-volume thoracentesis results in a statistically significant increase in TPTD-derived EVLWI. Because EVLWI was higher after removal of pleural fluid, we conclude that pleural effusions do not take part in single-indicator TPTD as a part of the pulmonary thermovolume and do not increase TPTD-derived EVLWI.