Respiratory failure caused by intratracheal saline: additive effect of xanthine oxidase.

Administration of physiological saline or drugs together with saline into the airways is becoming common clinical practice. However, there are few studies on possible side effects. We have studied the effects of saline, saline plus xanthine oxidase, and saline plus xanthine oxidase plus superoxidase dismutase on lung-thorax compliance and on arterial blood gases in anesthetized, paralyzed guinea pigs, ventilated for 2.5 h. Saline bolus (2-3 ml isotonic saline/kg body weight) into the airways reduced the compliance within 20 min to a mean of 39% of the pretreatment levels, and necessitated as increase in the respirator pressure. Saline plus xanthine oxidase decreased the compliance to 16% of the pretreatment levels. The xanthine oxidase-induced (but not saline-induced) decrease in lung compliance was relieved by superoxide dismutase. According to the present results xanthine oxidase induces a lung injury possible by production of free oxygen radicals. Superoxide dismutase can be valuable in prevention of free oxygen radical-mediated lung damage. Saline alone can be harmful when applied to the airways. This should be considered in clinical trials and in clinical practice.