Pretreatment with methylprednisolone shortens survival in a canine model of pseudomonas pneumonia

Abstract

The effectiveness of steroids in reducing the pulmonary damage of aspiration or endotoxemia is controversial. The following study was undertaken to test the hypothesis that steroid pretreatment beneficially influences cardiopulmonary function and survival in a standardized model for canine pseudomonas pneumonia. Thirty mongrel dogs were anesthetized (pentobarbital, pancuronium), intubated, and ventilated (16 cc/kg × 10/min) for 24 hr with 50% O 2/50% N 2O. Fourteen of the dogs were pretreated with methylprednisolone (30 mg/kg). The remaining 16 dogs received no steroids. Half of the animals in each group were ventilated with positive end expiratory pressure (10 cm H 2O) (PEEP), and half with zero end expiratory pressure (ZEEP). Sixteen of the animals received and endotracheal inoculation of pseudomonas. Statistically significant deterioration of physiological parameters was evident in infected, steroid-treated animals as early as 2 hr. These pronounced changes were delayed until 8 hr in the animals managed without steroids. The administration of steroids did not appear to enhance the integrity of the alveolar capillary membrane. The overall mortality for the infected animals was 75% with steroid treatment versus 38% without steroid. We conclude that methylprednisolone (30 mg/kg) offers no advantage in terms of cardiopulmonary performance or survival in this experimental model of canine pseudomonas pneumonia and endotoxemia. In fact, this evidence suggests that steroid pretreatment may be detrimental.