title: Analysis of pleural effusions in acute pulmonary embolism: radiological and pleural fluid data from 230 patients.
abstract: OBJECTIVE
  The aims of this study were to describe the frequency and radiographical characteristics of pleural effusions in a large population of patients with acute pulmonary embolism (PE) and characterize the pleural fluid biochemistry in those patients who underwent diagnostic thoracentesis.
  
  
  METHODS
  This was a retrospective observational single-centre study. A total of 230 consecutive patients with a diagnosis of PE over a 9-year period were enrolled. Spiral CT pulmonary angiography (52%) and high-probability ventilation and perfusion scans (42%) were used as the main reference methods.
  
  
  RESULTS
  Pleural effusions were observed in 32% and 47% of patients by CXR and CT, respectively. Typically, pleural effusions were small (90% occupied less than one third of the hemithorax) and unilateral (85%), but occasionally they reached more than a half of the hemithorax. On CT, 21% of pleural effusions showed loculation. In patients with loculated pleural fluid the diagnosis of PE had been delayed for a mean of 12.2 days after symptoms developed. The presence of pleural fluid was not related to infarction. Twenty-six of 93 (28%) patients with effusions on imaging underwent thoracentesis. All the fluids met Light's criteria for exudate, 58% contained erythrocyte counts >10,000/microL and 46% showed neutrophilic predominance.
  
  
  CONCLUSIONS
  Small pleural effusions, mostly unsuitable for diagnostic thoracentesis, were present in about one third of patients with PE. All the pleural effusions due to PE were exudates. If PE diagnosis was delayed the pleural effusion tended to become loculated.
authors.affiliation: Pleural Diseases Unit, Department of Internal Medicine, Arnau de Vilanova University Hospital, Lleida, Spain. jporcelp@yahoo.es
authors.forename: José M
authors.initials: JM
authors.lastname: Porcel
authors.forename: Ana B
authors.initials: AB
authors.lastname: Madroñero
authors.forename: Marina
authors.initials: M
authors.lastname: Pardina
authors.forename: Manuel
authors.initials: M
authors.lastname: Vives
authors.forename: Aureli
authors.initials: A
authors.lastname: Esquerda
authors.forename: Richard W
authors.initials: RW
authors.lastname: Light
mesh_terms: D000243:Adenosine Deaminase / Q000032:analysis*; D000368:Aged; D000792:Angiography; D005122:Exudates and Transudates / Q000737:chemistry / Q000166:cytology; D005260:Female; D005947:Glucose / Q000032:analysis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007770:L-Lactate Dehydrogenase / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D010996:Pleural Effusion / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism; D011655:Pulmonary Embolism / Q000150:complications* / Q000000981:diagnostic imaging; D013902:Radiography, Thoracic; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed
chemical_list: D007770:L-Lactate Dehydrogenase; D000243:Adenosine Deaminase; D005947:Glucose