Re-expansion Pulmonary Edema (RPE) is a well described, but rare complication after large volume thoracentesis. The creation of excessive negative pleural pressures (Ppl) has been postulated as a mechanism for the development of RPE. Previous studies in animal models have suggested that RPE is not seen when Ppl is kept greater than -20 cmH20. Similarly, an arbitrary cut-off of 1L has been suggested as a volume limit to minimize the risk of RPE. To date, no large series has examined the safety of large volume thoracentesis and risk of RPE in humans.
Data was collected prospectively during thoracentesis performed by the division of Interventional Pulmonology at Beth Israel Deaconess Medical Center from October 2001 to April 2005. Thoracentesis was performed using Pleura-Seal thoracentesis kit (Arrow-Clark) and pleural pressures were recorded either by simple water manometer or electronic transducer system (Biobench, National Instruments). Complications of thoracentesis were evaluated by medical record review and analysis of post-thoracentesis radiographic examinations.
Of the 602 patients in the database, 245 had greater than or equal to 1L of pleural fluid removed (range 1000-6550mL) and were included in analysis. Of those, 55 had greater than or equal to 2L removed and 12 had greater than 3L removed. Closing Ppl ranged from +15.6 to -29 cmH20. Nine cases (3.7%) had closing pleural pressures equal to -20 cmH20, and 10 cases (4.0%) had a closing Ppl less than -20 cmH20. One case (0.4%) of RPE was described radiographically, however, the patient suffered no adverse clinical outcomes, and specific treatment for RPE was not required. No case of hemodynamic instability was noted post-thoracentesis. Pneumothorax occurred in only 5 of 245 cases (2.0%).
Pleural fluid in excess of 6L has been safely removed without hemodynamic compromise or clinically significant RPE. The previously suggested pleural pressure cut-off of -20 cmH20 appears to confer a very low risk for RPE.
Large volume thoracentesis may be safely performed as long as attention is paid to pleural pressures.
David Berkowitz, None.