Pneumothorax Following Thoracentesis

BACKGROUND: Little is known about the factors related to the development of pneumothorax following thoracentesis. We aimed to determine the mean pneumothorax rate following thoracentesis and to identify risk factors for pneumothorax through a systematic review and meta-analysis. METHODS: We reviewed MEDLINE-indexed studies from January 1, 1966, through April 1, 2009, and included studies of any design with at least 10 patients that reported the pneumothorax rate following thoracentesis. Two investigators independently extracted data on the pneumothorax rate, risk factors for pneumothorax, and study methodological quality. RESULTS: Twenty-four studies reported pneumothorax rates following 6605 thoracenteses. The overall pneumothorax rate was 6.0% (95% confidence interval CI, 4.6%-7.8%), and 34.1% of pneumothoraces required chest tube insertion. Ultrasonography use was associated with significantly lower risk of pneumothorax (odds ratio OR, 0.3; 95% CI, 0.2-0.7). Lower pneumothorax rates were observed with experienced operators (3.9% vs 8.5%, P = .04), but this was nonsignificant within studies directly comparing this factor (OR, 0.7; 95% CI, 0.2-2.3). Pneumothorax was more likely following therapeutic thoracentesis (OR, 2.6; 95% CI, 1.8-3.8), in conjunction with periprocedural symptoms (OR, 26.6; 95% CI, 2.7-262.5), and in association with, although nonsignificantly, mechanical ventilation (OR, 4.0; 95% CI, 0.95-16.8). Two or more needle passes conferred a nonsignificant increased risk of pneumothorax (OR, 2.5; 95% CI, 0.3-20.1). CONCLUSIONS: Iatrogenic pneumothorax is a common complication of thoracentesis and frequently requires chest tube insertion. Real-time ultrasonography use is a modifiable factor that reduces the pneumothorax rate. Performance of thoracentesis for therapeutic purposes and in patients undergoing mechanical ventilation confers a higher likelihood of pneumothorax. Experienced operators may have lower pneumothorax rates. Patient safety may be improved by changes in clinical practice in accord with these findings.