Bile aspiration; An experimental study in rats

It is well known that aspiration of gastric contents causes severe pneumonitis either clinically or experimentally. Though gastric juice is often contaminated with bile regurgitated from the duodenum, the effects of bile on the large airways and lungs have not been well studied. To evaluate the effects of bile, cholic acid was used as the experimental solution. Fifteen female Wistar rats were anesthetized with ether and experimental solution (1 ml/kg) was injected intratracheally. Animals were divided into 4 groups: Group I (n=4) ether anesthesia without aspiration; Group II (n=2) received normal saline at a pH of 6.20; Group III (n=6) received cholic acid in 1% solution at a pH of 6.32; Group IV (n=3) received cholic acid in 0.5% solution at a pH of 6.28. The animals were killed 6 hours after aspiration. Examination of the tracheas by scanning electron microscopy in Group III and IV showed desquamation of the superficial cell layer with incomplete loss of ciliated cells. Examination of the lungs by light microscopy revealed severe pulmonary edema, atelectasis and focal hemorrhages in the same groups, Group I and II showed normal tracheas and lungs. We conclude that bile can cause marked damage to the tracheal mucosa and pulmonary parenchyma.