title: The acute effectiveness and safety of the constant-flow, pressure-volume curve to improve hypoxemia in acute lung injury.
abstract: OBJECTIVE
  To investigate the effectiveness of the constant-flow, pressure-volume curve (PVC) to prescribe positive end-expiratory pressure (PEEP) in acute lung injury (ALI) and risk of cardiopulmonary deterioration during the PVC process.
  
  
  METHODS
  A retrospective, cohort study.
  
  
  METHODS
  A surgical intensive care unit (ICU) of a tertiary, university hospital.
  
  
  METHODS
  Fifty consecutive ventilated patients diagnosed with ALI undergoing the PVC maneuver from 1999 to 2003.
  
  
  METHODS
  Titration of PEEP based on the lower inflection point of the constant-flow, pressure-volume curve.
  
  
  RESULTS
  Patients were divided into 2 groups based on PVC-guided PEEP changes of <3 cm H2O (PVC-NC or "no change") or ≥3 cm H2O (PVC-CHG or "change") from the initial empiric prescription. There was a greater increase in partial pressure of arterial oxygen (PaO2)/fractional concentration of inspired oxygen (FiO2) in the PVC-CHG group, with a mean change of 80 ± 50 (95% confidence interval [CI] 61, 98) versus 42 ± 54 (95% CI 17, 67) in the PVC-NC group. Eighty-two percent of patients (41/50) showed an increase in ratio of partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2) by 20% within 6 to 24 hours after the PVC test-greater in the PVC-CHG group (OR 1.44, 95% CI 1.02, 2.01). Thirteen percent (4/30) within the PVC-CHG group and none within the PVC-NC group (0/20) required a 25% increase in vasoactive infusion rates (P = .089) in relation to the procedure. Univariate logistic regression showed that PVC-CHG was significantly associated with a 20% change in PaO2/FiO2 (OR 7.54, 95% CI 1.37, 41.41). Multivariate logistic modeling showed that PVC-guided PEEP changes of ≥3 cm H2O, age ≤65 years, and pre-PVC FiO2 ≥ .85 were significantly associated with a 20% increase in PaO2/FiO2 (receiver operator area under the curve = .86).
  
  
  CONCLUSIONS
  In the setting of acute lung injury, use of the constant-flow, pressure-volume curve to prescribe PEEP appears associated with improvement in oxygenation with limited risk of acute, process-related, cardiopulmonary deterioration.
authors.affiliation: Center for Critical Care, Departments of General Anesthesiology and Outcomes Research, Cleveland Clinic Foundation, Cleveland, OH 44122, USA. hataj@ccf.org
authors.forename: J Steven
authors.initials: JS
authors.lastname: Hata
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Simmons
authors.forename: Avinash B
authors.initials: AB
authors.lastname: Kumar
authors.forename: John H
authors.initials: JH
authors.lastname: Rickelman
authors.forename: Ellen J
authors.initials: EJ
authors.lastname: Nickel
authors.forename: Shawn T
authors.initials: ST
authors.lastname: Simmons
authors.forename: James
authors.initials: J
authors.lastname: Torner
mesh_terms: D055371:Acute Lung Injury / Q000150:complications* / Q000628:therapy; D001811:Blood Volume Determination; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000209:etiology* / Q000517:prevention & control*; D000860:Hypoxia / Q000209:etiology / Q000628:therapy*; D007362:Intensive Care Units; D007385:Intermittent Positive-Pressure Ventilation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration