Corticosteroid treatment of experimental smoke inhalation

The effect of four corticosteroid analogs was evaluated in the treatment of smoke inhalation injury. Rats were exposed to white pine smoke for 15 minutes at 25 C, in a specially designed smoke apparatus. Methylprednisolone, 10 mg bid x 2d, starting one hour post exposure, was most effective in reducing expectant mortality (22.6%). A single injection of methylprednisolone, 20 mg, at one hour, resulted in a 76.7% reduction. There was no significant difference between the single injection of methylprednisolone and dexamethasone, 4 mg, but the administration of analogs with primarily mineralocorticoid activity, cortisone and hydrocortisone, actually increased mortality. In the control rats, marked interstitial edema occurred by 24 hours, the absence of which following treatment correlated closely with the results of the mortality study. This suggests that post exposure death due to white pine smoke is a result of direct lung injury, with increased endothelial and alveolar membrane permeability and edema, and that administration of glucosteroids in massive doses was effective in reducing this permeability and resultant edema.