Growth-arrest-specific 6 (GAS6) protein in ARDS patients: determination of plasma levels and influence of PEEP setting.

BACKGROUND: Growth-arrest-specific protein 6 (GAS6) is a vitamin K-dependent protein expressed by endothelial cells and leukocytes participating in cell survival, migration and proliferation and involved in many pathological situations. The aim of our study was to assess its implication in ARDS and its variation according to PEEP setting, considering that different cyclic stresses could alter GAS6 plasma levels. METHODS: Our subjects were enrolled in the ExPress study comparing a minimal alveolar distention (low-PEEP) ventilatory strategy to a maximal alveolar recruitment (high-PEEP) strategy in ARDS. Plasma GAS6, interleukin-8 (IL-8), and vascular endothelial growth factor (VEGF) levels were measured at day 0 and day 3 by enzyme-linked immunosorbent assay in blood samples prospectively collected during the study for a subset of 52 subjects included in 8 centers during year 2005. RESULTS: We found that GAS6 plasma level was elevated in the whole population at day 0: median 106 ng/mL IQR 77-139 ng/mL, with significant correlations with IL-8, the Simplified Acute Physiology Score II and the Organ Dysfunction and Infection scores. Statistically significant decreases in GAS6 and IL-8 plasma levels were observed between day 0 and day 3 in the high-PEEP group (P = .02); while there were no differences between day 0 and day 3 in the low-PEEP group. CONCLUSIONS: GAS6 plasma level is elevated in ARDS patients. The high-PEEP strategy is associated with a decrease in GAS6 and IL-8 plasma levels at day 3, without significant differences in day 28 mortality between the 2 groups. (Clinicaltrials.gov NCT00188058).

Positive end-expiratory pressure setting in adults with acute lung injury and acute respiratory distress syndrome: a randomized controlled trial.

CONTEXT: The need for lung protection is universally accepted, but the optimal level of positive end-expiratory pressure (PEEP) in patients with acute lung injury (ALI) or acute respiratory distress syndrome remains debated. OBJECTIVE: To compare the effect on outcome of a strategy for setting PEEP aimed at increasing alveolar recruitment while limiting hyperinflation to one aimed at minimizing alveolar distension in patients with ALI. DESIGN, SETTING, AND PATIENTS: A multicenter randomized controlled trial of 767 adults (mean [SD] age, 59.9 [15.4] years) with ALI conducted in 37 intensive care units in France from September 2002 to December 2005. INTERVENTION: Tidal volume was set at 6 mL/kg of predicted body weight in both strategies. Patients were randomly assigned to a moderate PEEP strategy (5-9 cm H(2)O) (minimal distension strategy; n = 382) or to a level of PEEP set to reach a plateau pressure of 28 to 30 cm H(2)O (increased recruitment strategy; n = 385). MAIN OUTCOME MEASURES: The primary end point was mortality at 28 days. Secondary end points were hospital mortality at 60 days, ventilator-free days, and organ failure-free days at 28 days. RESULTS: The 28-day mortality rate in the minimal distension group was 31.2% (n = 119) vs 27.8% (n = 107) in the increased recruitment group (relative risk, 1.12 [95% confidence interval, 0.90-1.40]; P = .31). The hospital mortality rate in the minimal distension group was 39.0% (n = 149) vs 35.4% (n = 136) in the increased recruitment group (relative risk, 1.10 [95% confidence interval, 0.92-1.32]; P = .30). The increased recruitment group compared with the minimal distension group had a higher median number of ventilator-free days (7 [interquartile range {IQR}, 0-19] vs 3 [IQR, 0-17]; P = .04) and organ failure-free days (6 [IQR, 0-18] vs 2 [IQR, 0-16]; P = .04). This strategy also was associated with higher compliance values, better oxygenation, less use of adjunctive therapies, and larger fluid requirements. CONCLUSIONS: A strategy for setting PEEP aimed at increasing alveolar recruitment while limiting hyperinflation did not significantly reduce mortality. However, it did improve lung function and reduced the duration of mechanical ventilation and the duration of organ failure. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00188058.