Saturday April 12, 2008
High PEEP doesn't decrease mortality though improve oxygenation !

Role of PEEP (positive-end–expiratory pressure) in ARDS (acute respiratory distress syndrome) is well known but what level of PEEP is beneficial is still not known. Here is a very important study of 983 consecutive patients with ALI(acute lung injury) and a P/F ratio not exceeding 250 - published recently in JAMA. (85% of the 983 study patients met criteria for ARDS at enrollment).

Objective: To compare an established low-tidal-volume ventilation strategy with an experimental strategy based on the original "open-lung approach," combining low tidal volume, lung recruitment maneuvers, and high positive-end–expiratory pressure.

Interventions
The control strategy (n=508) included

• target tidal volumes of 6 mL/kg of predicted body weight,
• plateau airway pressures not exceeding 30 cm H2O, and
• conventional levels of positive end-expiratory pressure

The experimental strategy (n=475) included

• target tidal volumes of 6 mL/kg of predicted body weight, plateau pressures not exceeding 40 cm H2O,
• recruitment maneuvers, and
• higher positive end-expiratory pressures

Main Outcome Measure: All-cause hospital mortality

Results

• Tidal volumes remained similar in the 2 groups,
• Mean positive end-expiratory pressures were 14.6 cm H2O in the experimental group vs 9.8 cm H2O among controls during the first 72 hours.
• All-cause hospital mortality rates were 36.4% and 40.4%, respectively
• Barotrauma rates were 11.2% and 9.1%
• The experimental group had lower rates of refractory hypoxemia (4.6% vs 10.2%), death with refractory hypoxemia (4.2% vs 8.9%), and previously defined eligible use of rescue therapies (5.1% vs 9.3%)

Conclusions: For patients with acute lung injury and acute respiratory distress syndrome, a multifaceted protocolized ventilation strategy designed to recruit and open the lung resulted in no significant difference in all-cause hospital mortality or barotrauma compared with an established low-tidal-volume protocolized ventilation strategy. This "open-lung" strategy did appear to improve secondary end points related to hypoxemia and use of rescue therapies.


Reference: click to get abstract

Ventilation Strategy Using Low Tidal Volumes, Recruitment Maneuvers, and High Positive End-Expiratory Pressure for Acute Lung Injury and Acute Respiratory Distress Syndrome, A Randomized Controlled Trial, JAMA. 2008;299(6):637-645, Feb. 2008