Effects of manganese superoxide dismutase, when given after inhalation injury has been established.

Abstract

To determine whether treatment with manganese superoxide dismutase (MnSOD), given intravenously after inhalation injury has been established, improves oxygenation and lung fluid balance. Randomized, controlled intervention trial. University research laboratory. Twenty-four chronically instrumented awake ewes with lung lymph fistulas. After smoke inhalation with 48 breaths of cotton smoke, the animals were assigned randomly to a control group (n = 6) or a treatment group, receiving 1000 units of MnSOD/kg (n = 6), 3000 units of MnSOD/kg (n = 6), or 9000 units of MnSOD/kg (n = 6) intravenously 1 hr after smoke inhalation. Different from the other three groups, in the group that received 3000 units of MnSOD, cardiac output and Pao2/Fio2 ratio did not significantly decrease throughout the experimental period. Apart from higher oxygen consumption in the group receiving 3000 units of MnSOD 24 hrs after smoke inhalation (263 +/- 44 mL/min vs. 182 +/- 36 mL/min; p < 0.05), no significant differences between treatment groups and control group were observed. Treatment with MnSOD given after smoke inhalation seems to be less effective then pretreatment with MnSOD, which was reported in previous studies to reduce the degree of inhalation injury.