Plasma Catalase and Glutathione Levels Are Decreased in Response to Inhalation Injury

We determined the effect of a severe smoke exposure on plasma oxidant and antioxidant activity. Adult sheep were given a smoke exposure while under anesthesia that produced a carboxyhemoglobin level of 45% +/- 3%. Twelve sheep were studied; six were given smoke alone and volume-resuscitated with sufficient lactated Ringer's solution to maintain baseline hemodynamics. This response was compared with six control sheep during a 6-hour period. The smoke inhalation injury produced a significant increase in plasma hydrogen peroxide and a significant decrease in plasma lipid peroxidation. Circulating lipid peroxidation did not correlate with tissue lipid peroxidation because lung and liver lipid peroxidation were significantly increased. The plasma antioxidants glutathione, catalase, and vitamin E were significantly reduced in response to the injury. Vitamin C remained unchanged from control. Circulatory failure is not a key element in this study, because lactate levels were controlled with volume resuscitation. The degree of smoke inhalation to the airway produced distant organ lipid peroxidation and a decrease in circulating antioxidants--without producing an increase in circulating lipid peroxidation. Maintaining circulating antioxidants may prevent distant organ lipid peroxidation and may be of clinical use in devising treatment strategies for smoke inhalation injury with the availability of antioxidants.