title: Pulmonary dead space fraction and pulmonary artery systolic pressure as early predictors of clinical outcome in acute lung injury.
abstract: OBJECTIVE
  The primary objective of this study was to test whether an elevated systolic pulmonary artery (PA) pressure or an elevated pulmonary dead space fraction (Vd/Vt) in early acute lung injury (ALI) is associated with poor clinical outcomes in the era of lung-protective ventilation.
  
  
  METHODS
  Prospective observational cohort study.
  
  
  METHODS
  ICUs of a university hospital.
  
  
  METHODS
  Forty-two patients with ALI receiving mechanical ventilation.
  
  
  METHODS
  PA pressure was measured noninvasively using transthoracic echocardiography. Vd/Vt was measured by volumetric capnography (NICO Cardiopulmonary Management System; Novametrix; Wallingford, CT).
  
  
  RESULTS
  There was no difference in the mean systolic PA pressure in patients who died compared to those who survived (43 +/- 9 mm Hg vs 41 +/- 9 mm Hg, p = 0.54) [mean +/- SD]. In contrast to the PA systolic pressure, Vd/Vt was significantly higher in patients who died compared to those who survived (0.61 +/- 0.09 vs 0.53 +/- 0.10, p = 0.02). Similarly, Vd/Vt was higher in patients with < 7 ventilator-free days during the first 28 days after enrollment compared to those with > 7 ventilator-free days (0.61 +/- 0.08 vs 0.52 +/- 0.11, p = 0.008).
  
  
  CONCLUSIONS
  In the era of lung-protective ventilation, systolic PA pressure early in the course of ALI is elevated but not predictive of outcome. However, elevated Vd/Vt in early ALI is associated with increased mortality and with fewer ventilator-free days.
authors.affiliation: Department of Anesthesia, University of California, San Francisco, San Francisco, CA, USA.
authors.forename: Magda
authors.initials: M
authors.lastname: Cepkova
authors.forename: Vineet
authors.initials: V
authors.lastname: Kapur
authors.forename: Xiushui
authors.initials: X
authors.lastname: Ren
authors.forename: Thomas
authors.initials: T
authors.lastname: Quinn
authors.forename: Hanjing
authors.initials: H
authors.lastname: Zhuo
authors.forename: Elyse
authors.initials: E
authors.lastname: Foster
authors.forename: Kathleen D
authors.initials: KD
authors.lastname: Liu
authors.forename: Michael A
authors.initials: MA
authors.lastname: Matthay
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011669:Pulmonary Wedge Pressure; D012121:Respiration, Artificial; D012126:Respiratory Dead Space; D012128:Respiratory Distress Syndrome / Q000401:mortality* / Q000503:physiopathology* / Q000628:therapy; D015996:Survival Rate; D013599:Systole; D016896:Treatment Outcome