title: Pneumothorax following thoracentesis: a systematic review and meta-analysis.
abstract: 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.
authors.affiliation: Renal Section, Department of Medicine, Boston University Medical Center, Boston, MA 02118, USA. craig.gordon@bmc.org
authors.forename: Craig E
authors.initials: CE
authors.lastname: Gordon
authors.forename: David
authors.initials: D
authors.lastname: Feller-Kopman
authors.forename: Ethan M
authors.initials: EM
authors.lastname: Balk
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Smetana
mesh_terms: D000367:Age Factors; D002983:Clinical Competence; D004322:Drainage / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D019152:Paracentesis / Q000009:adverse effects*; D035422:Pleural Cavity / Q000601:surgery*; D011030:Pneumothorax / Q000453:epidemiology*; D012307:Risk Factors; D012737:Sex Factors