Original Research The Acute Effectiveness and Safety of the Constant-Flow, Pressure-Volume Curve to Improve Hypoxemia in Acute Lung Injury

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. Design: A retrospective, cohort study. Setting: A surgical intensive care unit (ICU) of a tertiary, university hospital. Patients: Fifty consecutive ventilated patients diagnosed with ALI undergoing the PVC maneuver from 1999 to 2003. Interventions: Titration of PEEP based on the lower inflection point of the constant-flow, pressure-volume curve. Measure-ments and Main Results: Patients were divided into 2 groups based on PVC-guided PEEP changes of <3 cm H2O (PVC-NC or ‘‘no change’’) or3 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