Cardiopulmonary effects of matching positive end-expiratory pressure to abdominal pressure in concomitant abdominal hypertension and acute lung injury.

BACKGROUND

To evaluate the cardiopulmonary effects of positive end-expiratory pressure (PEEP) equalization to intra-abdominal pressure (IAP) in an experimental model of intra-abdominal hypertension (IAH) and acute lung injury (ALI).

METHODS

Eight anesthetized pigs were submitted to IAH of 20 mm Hg with a carbon dioxide insufflator for 30 minutes and then submitted to lung lavage with saline and Tween (2.5%). Pressure x volume curves of the respiratory system were performed by a low flow method during IAH and ALI, and PEEP was subsequently adjusted to 27 cm . H2O for 30 minutes.

RESULTS

IAH decreases pulmonary and respiratory system static compliances and increases airway resistance, alveolar-arterial oxygen gradient, and respiratory dead space. The presence of concomitant ALI exacerbates these findings. PEEP identical to AP moderately improved oxygenation and respiratory mechanics; however, an important decline in stroke index and right ventricle ejection fraction was observed.

CONCLUSIONS

Simultaneous IAH and ALI produce important impairments in the respiratory physiology. PEEP equalization to AP may improve the respiratory performance, nevertheless with a secondary hemodynamic derangement.