Alterations in the course of acid-induced lung injury in rats after general anesthesia: volatile anesthetics versus ketamine.

UNLABELLED: Pulmonary aspiration of gastric acid is a complication that occurs during anesthesia. The effects of the often used anesthetics on the inflammatory response after aspiration of acid are not known. We examined the effects of three different inhaled anesthetics--halothane, enflurane, and isoflurane--as well as parenteral ketamine, on the associated immediate mortality, alveolar protein leakage, and morphometric changes after intrapulmonary instillation of acidic solution in rats. Animals in deep state of anesthesia had a higher mortality after the instillation of acidic solutions than those in lighter stages (82.5% vs 31.6%). Protein leakage over 5 h was greater in the animals receiving volatile anesthetics (range 0.9-1.2) compared with those receiving ketamine (0.6 +/- 0.05). Desferoxamine did not decrease protein leakage in acid-injured animals (1.1 +/- 0.06 vs 1.02 +/- 0.08). Furthermore, volatile anesthetics resulted in an increase in the acute inflammatory response and leukocytic infiltration compared with ketamine in acid-injured lungs. We conclude that the administration of inhaled anesthetics was associated with exacerbation of an acute inflammatory response after aspiration of acidic solution. Lung injury was not increased with ketamine anesthesia. This difference was the result of the hypotensive effects of inhaled anesthetics.

IMPLICATIONS: This study reveals that the use of inhaled anesthetics aggravates inflammation secondary to gastric aspiration and should be avoided on diagnosis of the situation.