Abdomen release in prone position does not improve oxygenation in an experimental model of acute lung injury

Objective: To analyze the effect of abdomen release in the prone position o n oxygenation in an experimental model of acute lung injury. Design: Experimental randomized controlled study. Setting: Experimental laboratory of a tertiary university hospital. Participants: Mixed-breed adolescent pigs weighing between 25-31 kg. Interventions: Thirty minutes after pulmonary edema was produced with oleic acid, the animals were turned prone and randomized into two groups: group I or control (n = 9), lying directly on the operating table; and group II ( n = 11) with abdomen release, with positioning roils under the upper part o f the chest wall and the pelvis to allow free movement of the abdomen. Measurements and results: The gas exchange, respiratory mechanics, hemodyna mics, intra-abdominal pressure (IAP) and the extravascular lung water (EVLW ), determined by double indicator dilution method (DI), were recorded at ba seline (time 0) and at 30, 60, 90, 120 and 150 min. The PaO2/FIO2 increased in both groups at 30 min after the pigs were placed in the prone position (time 60) and then decreased progressively until the end of the experimenta l period, with no statistical differences between the groups at any time (7 3.1 +/- 14.5 vs 79.5 +/- 14.9 at 150 min). Abdomen release was not associat ed with changes in the respiratory mechanics, EVLW or intra-abdominal press ure. Conclusions: Abdomen release in prone position does not improve oxygenation in an experimental model of acute lung injury.