Objective: To evaluate patient-related and procedure-related risk factors for thoracentesis-related pneumothorax.
Design: Prospective, nonrandomized cohort study.
Setting: Pulmonary Special Procedures Unit of a university medical center.
Methods: Thoracentesis using either a 22-gauge, a Boutin, or a Cope needle (depending on availability and operator preference) was performed by the pulmonary faculty or by pulmonary physicians-in-training under faculty supervision. In order to control for effusion size and the presence of loculations, chest radiography and pleural ultrasonography were performed prior to each thoracentesis. Potential patient-related and procedure-related risk factors for pneumothorax were analyzed at the procedure level using the presence or absence of pneumothorax on the postprocedure chest radiograph as the sole outcome variable.
Results: Two hundred fifty-five thoracenteses were performed in 205 adult patients (113 men and 92 women; mean age, 58.8+/-18 years) over a 3(1/2)-year period. One hundred fifty procedures were performed for diagnostic purposes, 28 procedures were performed for therapeutic purposes, and 77 procedures were performed for both diagnostic and therapeutic purposes. Based on the radiographic criteria, 152 effusions (60%) were small. Loculations were present in 76 patients (30%). Pneumothoraces occurred in 14 instances (5.4%), and chest tube drainage was required in 2 instances (0.78%). Hospitalization status, critical illness, effusion size or type, presence of loculations, operator, needle type, amount of fluid withdrawn, occurrence of dry tap, and type of thoracentesis were not associated with an increased frequency of pneumothorax. The only predictor variable demonstrating statistical significance was repeated thoracentesis.
Conclusion: The results of a bivariate analysis suggest that pneumothorax following thoracentesis is a rare event that is not easily predictable when the procedure is performed by experienced operators in a controlled setting.