title: Implications of early versus late bilateral pulmonary infiltrates in patients with aneurysmal subarachnoid hemorrhage.
abstract: BACKGROUND
  Bilateral pulmonary infiltrates occur frequently following aneurysmal subarachnoid hemorrhage (SAH), and may be associated with worse outcomes. The etiology, natural history, and prognosis of infiltrates occurring soon after SAH may differ from the characteristics of infiltrates developing at a later time.
  
  
  METHODS
  We performed a retrospective cohort study involving 245 consecutive patients with a ruptured cerebral aneurysm to assess the association between "early" (< or = 72 h) or "late" (>72 h) bilateral pulmonary infiltrates and subsequent death or neurologic impairment. We used logistic regression models to adjust for baseline differences in age, level of consciousness, amount of blood on computed tomography, and the presence or absence of clinical vasospasm.
  
  
  RESULTS
  Sixty-seven patients (27%) developed bilateral pulmonary infiltrates. Of these, 36 (54%) had early infiltrates, 24 (36%) had late infiltrates, and 7 (10%) had both. Twenty-eight patients (11% of entire cohort) met criteria for acute respiratory distress syndrome (ARDS). Patients with early infiltrates were more likely to have presented with stupor or coma than patients who developed infiltrates later (64% vs. 29%, P < 0.01). In multivariable analysis, late pulmonary infiltrates were strongly predictive of poor outcome (OR 5.0, 95% CI 1.9-13.6, P < 0.01), while early infiltrates were not (OR 1.2, 95% CI 0.5-3.0, P = 0.66).
  
  
  CONCLUSIONS
  Bilateral pulmonary infiltrates after SAH most often occur within three days of aneurysm rupture. However, only infiltrates occurring beyond this time are independently associated with poor outcome. Increased emphasis on the prevention of late pulmonary complications has the potential to improve outcomes in SAH.
authors.affiliation: Department of Critical Care Medicine, Foothills Medical Center, University of Calgary, Room EG23J, 1403 29th St. NW, Calgary, AB, Canada, T2N 2T9. andreas.kramer@calgaryhealthregion.ca
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Kramer
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Bleck
authors.forename: Aaron S
authors.initials: AS
authors.lastname: Dumont
authors.forename: Neal F
authors.initials: NF
authors.lastname: Kassell
authors.forename: Claire
authors.initials: C
authors.lastname: Olson
authors.forename: Bart
authors.initials: B
authors.lastname: Nathan
mesh_terms: D015331:Cohort Studies; D003422:Critical Care; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications* / Q000628:therapy; D008171:Lung Diseases / Q000175:diagnosis / Q000209:etiology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000150:complications* / Q000628:therapy; D013997:Time Factors; D016896:Treatment Outcome