Effect of ventilation with positive end-expiratory pressure on the development of lung damage in experimental acid aspiration pneumonia in the rabbit.

Sixteen anaesthetized rabbits were subjected to tracheostomy and lung damage produced by the instillation of 4.5 ml/kg hydrochloric acid (pH 1.5) into the trachea. Half of the animals were ventilated with a positive end-expiratory pressure (PEEP) of 3 cmH2O and half with a PEEP of 10 cmH2O for 5 h, the mean airway pressure being kept at 12 cmH2O by adjustment of the end-inspiratory pause time. Pressure-volume curves were recorded every hour. Although the arterial PO2 values and compliance above the inflection point on the pressure-volume curve were greater in the group submitted to 10 cmH2O PEEP, there were no significant differences between the groups in terms of survival and histological findings.