Aspiration pneumonia: treatment with osmotically active agents

Utilizing the ex vivo perfused ventilated canine pulmonary lobe, we evaluated the effects of three osmotically active agents on pulmonary function after acid aspiration. Control lobes were stable during a 44-hour perfusion with minimal weight gain, stable pulmonary artery and end-inspiratory pressures, and no increase in intrapulmonary shunting. After acid aspiration during a 44-hour perfusion period, massive weight gain occurred (228 gm), pulmonary artery and end-inspiratory pressure increased, and marked intrapulmonary shunting (44%) developed. When mannitol (molecular weight 182) or dextran 40 (molecular weight 40,000) were added to the perfusate of the acid-instilled lobes, no significant modifications of the acid-induced response were seen during the 44-hour perfusion. The administration of albumin (molecular weight 69,000), however, markedly modified the acid-induced response. Weight gain (53 gm) was almost completely eliminated, pulmonary artery and end-inspiratory pressures were stable, and intrapulmonary shunting increased only minimally (10%). It is concluded that despite the permeability change in the capillary-alveolar membrane produced by acid aspiration, albumin is retained within the vascular space and is effective in reducing the injury response.