Histopathologic effects of lipid content of enteral solutions after pulmonary aspiration in rats

We compared the pulmonary histopathologic effects of different enteral formulas with various lipid contents during the subacute period of aspiration in rats.

Fifty Wistar albino rats, weighing 180 to 300 g, were randomly assigned to one of five groups (n = 10). Anesthesia was induced with an intraperitoneal injection of 100 mg/kg of ketamine hydrochloride, rats were intubated endotracheally with a 16-gauge angiocatheter, and 0.9% saline (group 1, control), Impact (group 2), Jevity (group 3), Biosorb Energy Plus (group 4), or Pulmocare (group 5) with a lipid content of 0, 28, 39.3, 58, or 93.3 g/L, respectively, was injected into the lungs in a volume of 3 mL/kg. Seven days later, rats were killed, and lungs with trachea were removed en bloc for histopathologic examination. For histopathologic assessment, slides were examined for the presence of peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar histiocytes, interstitial fibrosis, granuloma, and necrosis formation. The degree of severity was assessed by using a 4-point scale. One-way analysis of variance and Student-Newman-Keuls test were used for statistical analysis.

Peribronchial inflammatory cell infiltration was present in all groups but was significantly more severe in group 2 than in groups 1, 4, and 5 (P < 0.05). Alveolar edema was statistically higher in group 2 than in group 1 (P < 0.05). Alveolar septal infiltration was statistically higher in group 4 than in group 1. Alveolar histiocytes were statistically higher in groups 2 and 3 (P < 0.01) and groups 4 and 5 (P < 0.05) than in group 1. Alveolar exudate, interstitial fibrosis, granuloma, and necrosis formation were absent in all groups.

The pulmonary histopathologic effects of aspiration of Impact were severe peribronchial inflammatory cell infiltration (greater than aspiration of Biosorb and Pulmocare), abundant alveolar histiocytes, and alveolar edema in comparison with aspiration of saline, even though Impact had the lowest lipid content of all studied formulas. We concluded that the tissue damage occurring after pulmonary aspiration of Impact is more severe than after aspiration of Pulmocare.