Evaluation of patient-related and procedure-related factors contributing to pneumothorax following thoracentesis

Objective: To evaluate patient-related and procedure-related risk factors f or 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, ol a Cope needle (depending on availability and operator preference) was performed by the pu lmonary faculty or by pulmonary physicians-in-training under faculty superv ision. In order to control for effusion size and the presence of loculation s, chest radiography and pleural ultrasonography were performed prior to ea ch thoracentesis. Potential patient-related and procedure-related risk fact ors for pneumothorax were analyzed at the procedure le cel using the presen ce 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 p atients (113 men and 92 women; mean age, 58.8 +/- 18 years) over a 3 1/2-ye ar period. One hundred fifty procedures were performed for diagnostic purpo ses, 28 procedures were performed for therapeutic purposes, and 77 procedur es were performed for both diagnostic and therapeutic purposes. Based on th e radiographic criteria, 152 effusions (60%) were small, Loculations were p resent in 76 patients (30%). Pneumothoraces occurred in 14 instances (5.4%) , and chest tube drainage was required in 2 instances (0.78%). Hospitalizat ion status, critical illness, effusion size or type, presence of loculation s, operator, needle type, amount of fluid withdrawn, occurrence of dry tap, and type of thoracentesis were not associated with an increased frequency of pneumothorax.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 sign ificance was repented thoracentesis. Conclusion: The results of a bivariate analysis suggest that pneumothorax f ollowing thoracentesis is a rare event that is not easily predictable when the procedure is performed by experienced operators in a controlled setting .