The Impact of Continuous Positive Airway Pressure upon Pleural Fluid Pressures during Thoracentesis

Background: Excessive drop of pleural pressure (Ppl) during therapeutic thoracentesis may be related to adverse events and/or to repeated procedures due to incomplete drainage. Objective: This was a pilot study of the impact of the application of continuous positive airway pressure (CPAP) at +5 cm H2O upon the Ppl profile during thoracentesis. Methods: This was a prospective, controlled study of 49 consecutive adults who underwent thoracentesis. Enrollment was via alternation on a one-to-one basis. Pleural manometry was used to compare serial Ppl in patients using CPAP at +5 cm H2O (CPAP group) with Ppl in patients without CPAP (control group). Results: Mean volumes drained were comparable between CPAP and control groups (1,380 vs. 1,396 mL). Patients in the CPAP group had a significantly greater change in volume per centimeter water column pressure (p = 0.0231, 95% confidence interval 6.41-82.61). No patient in the CPAP group had a Ppl less than -20 cm H2O at termination of the procedure, while 8 (33%) control group patients developed a pressure lower than -20. No patient in either group developed re-expansion pulmonary edema. Conclusion: The application of CPAP at +5 cm H2O mitigates the decreases in Ppl caused by thoracentesis via an increase in pleural compliance. The clinical implications of this finding merit study.