To determine whether patients’ symptoms during thoracentesis correspond to changes in pleural pressure.
Data was collected prospectively during thoracenteses performed from 9/2002-12/2004. Of 468 patients, 169 had pleural manometry and were included in this study. Pleural pressures were measured with either a simple water manometer or an electronic transducer system. End expiratory pleural pressures were recorded after the withdrawal of 5cc of fluid (opening pressure), and until either there was no more fluid present or the patient developed chest discomfort (closing pressure).
Twenty eight of the 169 patients (16%) developed symptoms during thoracentesis: 10/169(5%) with cough, 18/169(11%) with chest discomfort. Total volume of pleural fluid removed was not different between the three groups (asymptomatic 1219±76ml, cough 1338±286ml, pain 1136±213ml), nor were opening pressures. Closing pleural pressures were significantly lower in patients with chest pain (-13±2.4cmH20) than in those without symptoms (-6.8±0.8cmH20) p=0.04, but not in those with cough (-6.8±3.2cmH20) p=0.1. The total change in pleural pressure (opening-closing pressure) was significantly greater in patients with chest pain (-20±1.7) than those without symptoms (-12.4±0.6) and those with cough (-9.5±2.2), p<0.001. There were no differences in pleural pressures between patients with cough and without symptoms.
This study is the first to demonstrate a relationship between patient symptoms and pleural pressure changes during thoracentesis. Chest discomfort was associated with large negative pleural pressure changes, which may increase risk for re-expansion pulmonary edema, and should be a signal to terminate thoracentesis. Cough was not associated with increased changes in pleural pressure and may be a sign of resolving atelectasis during volume removal. Manometry is recommended to prevent pressure-related complications and maximize volume of fluid removal during thoracentesis. However, if unavailable, patient symptoms may be a surrogate for pleural manometry.
Symptoms during thoracentesis correspond to pleural pressure changes. Cough is not related to high-risk negative pleural pressure. Chest discomfort is associated with large negative-pleural pressure changes and should lead to termination of thoracentesis.
Allan Walkey, None.