title: Predictors of an intermediate ventilation/perfusion lung scan in patients with suspected acute pulmonary embolism.
abstract: BACKGROUND
  An intermediate ventilation/perfusion (V/Q) lung scan lacks diagnostic utility in excluding acute pulmonary embolism (PE).
  
  
  OBJECTIVE
  To identify the potential predictors of an intermediate V/Q lung scan in patients with suspected acute PE.
  
  
  METHODS
  A review of the medical records of 306 consecutive patients with suspected acute PE, in whom a V/Q lung scan was performed (interpretation using modified Prospective Investigation of Pulmonary Embolism Diagnosis criteria).
  
  
  RESULTS
  A total of 274 patients (89.5%) had a non-intermediate V/Q lung scan: 88 (28.8%) high probability, 149 (48.7%) low probability, and 37 (12.1%) near normal/normal. Thirty-two patients (10.5%) had an intermediate V/Q lung scan. Patients with an intermediate V/Q lung scan presented a significantly greater frequency of age greater than 70 years (81.2 versus 50.4%, P=0.01), previous cardiopulmonary disease (75 versus 46.3%, P=0.003), chronic obstructive pulmonary disease (34.4 versus 15.7%, P=0.01), and chest radiograph evidence of emphysema (18.7 versus 4.7%, P=0.008). We found no other significant differences in the rest of the characteristics studied between patients with an intermediate and a non-intermediate V/Q lung scan.
  
  
  CONCLUSIONS
  The possibility of an intermediate V/Q lung scan is higher in elderly patients and in patients with previous cardiopulmonary disease (especially with chronic obstructive pulmonary disease). Emphysema is the only chest radiograph abnormality associated with a greater possibility of an intermediate V/Q lung scan.
authors.affiliation: Department of Internal Medicine, Hospital de Zafra, Zafra, Badajoz, Spain. jmcromero@eresmas.com
authors.forename: José María
authors.initials: JM
authors.lastname: Calvo-Romero
authors.forename: Esther María
authors.initials: EM
authors.lastname: Lima-Rodríguez
authors.forename: Pedro
authors.initials: P
authors.lastname: Bureo-Dacal
authors.forename: Manuel
authors.initials: M
authors.lastname: Pérez-Miranda
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D011237:Predictive Value of Tests; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011859:Radiography; D012189:Retrospective Studies; D014692:Ventilation-Perfusion Ratio