title: Etiologies of bilateral pleural effusions.
abstract: BACKGROUND
  To evaluate the safety, etiology and outcomes of patients undergoing bilateral thoracentesis.
  
  
  METHODS
  This is a prospective cohort study of 100 consecutive patients who underwent bilateral thoracenteses in an academic medical center from July 2009 through November 2010. Pleural fluid characteristics and etiologies of the effusions were assessed. Mean differences in levels of fluid characteristics between right and left lungs were tested. Associations between fluid characteristics and occurrence of bilateral malignant effusions were evaluated. The rate of pneumothorax and other complications subsequent to bilateral thoracentesis was determined.
  
  
  RESULTS
  Exudates were more common than transudates, and most effusions had multiple etiologies, with 83% having two or more etiologies. Bilateral malignant effusions occurred in 19 patients, were the most common single etiology of exudative effusions, and were associated with higher levels of protein and LDH in the pleural fluid. Among 200 thoracenteses performed with a bilateral procedure, seven resulted in pneumothoraces, three of which required chest tube drainage and four were ex vacuo.
  
  
  CONCLUSIONS
  More often than not, there are multiple etiologies that contribute to pleural fluid formation, and of the combinations of etiologies observed congestive heart failure was the most frequent contributor. Exudative effusions are more common than transudates when bilateral effusions are present. Malignancy is a common etiology of exudative effusions. This study suggests that the overall complication rate following bilateral thoracentesis is low and the rate of pneumothorax subsequent to bilateral thoracentesis is comparable to unilateral thoracentesis.
authors.affiliation: Yale University, Section of Pulmonary and Critical Care Medicine, United. jonathan.puchalski@yale.edu
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Puchalski
authors.forename: A Christine
authors.initials: AC
authors.lastname: Argento
authors.forename: Terrence E
authors.initials: TE
authors.lastname: Murphy
authors.forename: Katy L B
authors.initials: KL
authors.lastname: Araujo
authors.forename: Isabel B
authors.initials: IB
authors.lastname: Oliva
authors.forename: Ami N
authors.initials: AN
authors.lastname: Rubinowitz
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Pisani
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005122:Exudates and Transudates; D005260:Female; D006333:Heart Failure / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D019152:Paracentesis / Q000009:adverse effects* / Q000379:methods; D010996:Pleural Effusion / Q000209:etiology*; D016066:Pleural Effusion, Malignant / Q000209:etiology; D011030:Pneumothorax / Q000209:etiology; D011446:Prospective Studies; D016896:Treatment Outcome