Elevated Blood Cyanide Concentrations in Victims of Smoke Inhalation

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BackgroundThe nature of the toxic gases that cause death from smoke inhalation is not known. In addition to carbon monoxide, hydrogen cyanide may be responsible, but its role is uncertain, because blood cyanide concentrations are often measured only long after exposure.MethodsWe measured cyanide concentrations in blood samples obtained at the scene of residential fires from 109 fire victims before they received any treatment. We compared the results with those in 114 persons with drug intoxication (40 subjects), carbon monoxide intoxication (29 subjects), or trauma (45 subjects). The metabolic effect of smoke inhalation was assessed by measuring plasma lactate at the time of admission to the hospital in 39 patients who did not have severe burns.Results.The mean (±SD) blood cyanide concentrations in the 66 surviving fire victims (21.6±36.4 μmol per liter, P<0.001) and the 43 victims who died (116.4±89.6 μmol per liter, P<0.001) were significantly higher than those in the 114 control subjects (5.0±5.5 μmol per liter). Among the 43 victims who died, the blood cyanide concentrations were above 40 μmol per liter in 32 (74 percent), and above 100 μmol per liter in 20 of these (46 percent). There was a significant correlation between blood cyanide and carbon monoxide concentrations in the fire victims (P<0.001). Plasma lactate concentrations at the time of hospital admission correlated more closely with blood cyanide concentrations than with blood carbon monoxide concentrations. Plasma lactate concentrations above 10 mmol per liter were a sensitive indicator of cyanide intoxication, as defined by the presence of a blood cyanide concentration above 40 μmol per liter.ConclusionsResidential fires may cause cyanide poisoning. At the time of a patient's hospital admission, an elevated plasma lactate concentration is a useful indicator of cyanide toxicity in fire victims who do not have severe burns. (N Engl J Med 1991;325:1761–6.)SMOKE inhalation has been well established as a cause of death in fire victims.123 The identity of the toxic gases leading to death is uncertain, however. In addition to carbon monoxide, hydrogen cyanide is a major source of concern. The thermal decomposition of various nitrogen-containing materials, either natural (such as wool and silk) or synthetic (such as polyurethane and polyacrylonitrile), can produce toxic levels of hydrogen cyanide.345678 For example, the thermal degradation of 1 g of polyacrylonitrile in a 15.6-liter combustion chamber produces a hydrogen cyanide concentration of 1500 ppm.6 Bertol et al. estimated that a lethal concentration of hydrogen …

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