Prophylactic and delayed treatment with high-dose methylprednisolone in a porcine model of early ARDS induced by endotoxaemia

Abstract

The effects of prophylactic and delayed treatment with high-dose methylprednisolone were evaluated in a porcine model of early adult respiratory distress syndrome induced by endotoxaemia. Spontaneously breathing pigs under ketamine anaesthesia were infused i.v. with E. coli endotoxin (10 micrograms . h-1 . kg-1) over 6h. Twenty animals received endotoxin without treatment. Eight animals were pretreated with methylprednisolone i.v., 60 mg . kg-1, followed by an i.v. infusion at a rate of 10 mg . h-1 . kg-1. Ten animals received the same dosage of methylprednisolone beginning 2 h after the start of endotoxin infusion. Pretreatment with methylprednisolone prevented the endotoxin-induced impairment in pulmonary gas exchange and the development of pulmonary oedema. The pulmonary hypertension was counteracted. Cardiac output (Qt) and O2 delivery were improved. Mean arterial blood pressure (MAP) increased and was higher than in the untreated endotoxin group. The profound fall in PMN count was inhibited, while the accumulation of these cells in the lung was still substantial. Survival was improved. Delayed methylprednisolone treatment prevented further deterioration in pulmonary gas exchange and tended to restore it towards baseline. The pulmonary oedema and pulmonary hypertension were reduced. Qt and O2 delivery did not improve. MAP was higher than in the untreated endotoxin group towards the end of the observation period. The decline in PMN count and the pulmonary accumulation of these cells were not significantly influenced. Survival was improved. These results indicate that high-dose methylprednisolone, when given early in the course of sepsis, might be of clinical value in prevention of the devastating pulmonary and circulatory complications of this disease.