A new method for performing continuous manometry during pleural effusion drainage.

BACKGROUND Pleural manometry can predict the presence of trapped lung and guide large-volume thoracentesis. The current technique for pleural manometry transduces pressure from the needle or intercostal catheter, necessitating intermittent cessation of fluid drainage at the time of pressure recordings. OBJECTIVES To develop and validate a technique for performing continuous pleural manometry, where pressure is transduced from an epidural catheter that is passed through the drainage tube to sit within the pleural space. METHODS Pleural manometry was performed on 10 patients undergoing thoracentesis of at least 500 ml, using the traditional intermittent and new continuous technique simultaneously, and pleural pressures were recorded after each drainage of 100 ml. The pleural elastance (PEL) curves and their 95% confidence intervals (CIs), derived using measurements from each technique, were compared using the analysis of covariance and Student's paired t test, respectively. RESULTS There was no significant difference in PEL calculated using each method (p > 0.1); however, there was a trend towards the CI for the PEL derived from the continuous method being narrower (p = 0.08). Fully automated measurement of drainage volume and pleural pressure, with real-time calculation and display of PEL, was achieved by connecting the system to a urodynamics machine. CONCLUSIONS Pleural manometry can be transduced from an epidural catheter passed through the drainage tube into the pleural space, which gives continuous recording of the pleural pressure throughout the procedure. This allows for automated calculation and display of the pleural pressure and PEL in real time, if the system is connected to a computer with appropriate software.