Value of lactic acidosis in the assessment of the severity of acute cyanide poisoning.

OBJECTIVE: To test the hypothesis that plasma lactate concentrations could be of confirmatory value in patients with histories consistent with acute pure cyanide poisoning because immediate laboratory confirmation of suspected cyanide poisoning is rarely possible and because clinicians must rapidly decide whether to administer specific antidotes, which may have severe side effects. DESIGN: Retrospective clinical study. SETTING: An intensive care unit in a university-affiliated teaching hospital. PATIENTS: All acute cyanide-poisoned patients admitted to our intensive care unit, excluding fire victims, from 1988 to 1999. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Eleven patients were studied. Before antidotal treatment, the median plasma lactate concentration was 168 mg/dL, the median blood cyanide concentration was 4.2 mg/L. Using Spearman's test, there was a significant correlation between plasma lactate and blood cyanide concentrations ( =.74, =.017). Before antidotal treatment, plasma lactate concentration correlated positively with anion gap and inversely with systolic blood pressure, spontaneous respiratory rate, and arterial pH. During the course of cyanide poisonings, a plasma lactate concentration of >or=72 mg/d/L (8 mmol/L) was sensitive (94%) and moderately specific (70%) for a toxic blood cyanide concentration (>or=1.0 mg/L). The specificity was substantially improved in patients not receiving catecholamines (85%). CONCLUSIONS: The immediate and serial measurement of plasma lactate concentrations is useful in assessing the severity of cyanide poisoning.

Assessment of erythrocyte cholinesterase activity in victims of smoke inhalation.

BACKGROUND: The nature of the toxic gases that cause death from smoke inhalation is incompletely understood, and the mechanisms leading to incapacitation remain to be determined. Thermal degradation products of various compounds, including phosphorous-based fire retardants, are suspected capable of impairing human cholinesterase activity. The aim of this study was to measure the erythrocyte cholinesterase activity in victims of smoke inhalation. METHODS: We prospectively measured the erythrocyte cholinesterase activity in blood samples obtained at the scene of residential fires from 49 fire victims. We compared the results with those in an unmatched group of 45 persons with acute drug poisoning. RESULTS: The median (25th-75th percentiles) erythrocyte cholinesterase activity in the 49 fire victims, 1968 IU/L (1660-2276), was significantly lower than in the 45 control subjects 2460 IU/mL (1968-2890), (p = 0.0004). There was no significant difference of the red blood cell counts or plasma protein levels between the 2 groups, while the hematocrit was significantly greater in the fire victims than in the drug-poisoned patients. There was a significant correlation between blood cyanide and carbon monoxide concentrations in the fire victims (r = 0.494, p = 0.002). There was no correlation between erythrocyte cholinesterase activity and either blood cyanide (r = 0.11, p = 0.44) or blood carbon monoxide concentrations (r = 0.04, p = 0.78). CONCLUSIONS: We found a significantly lower level of erythrocyte cholinesterase activity in victims of residential fires, when compared with a convenience sample of hospitalized poisoned patients. Despite the limitations of the study, investigations of the toxic gases potentially responsible for impairment of cholinesterase activity and the clinical significance of this lower enzymatic activity merit further investigation.

Rapid quantitative determination of cyanide in biological fluids from coyotes killed with a coyote getter.

A number of methods for the determination of cyanide in biological fluids have been published. Many are not really rapid or else rely on elaborate specialized equipment. The method reported here is rapid, uses only inexpensive disposable, and produces a quantitative result within 1 minute on as little as a few drops of blood. Cyanide concentrations found by this method in the blood of coyotes killed by sodium cyanide blasted into the mouth with a snub-nosed gun concealed in bait are given and discussed. Cyanide levels in blood from the left ventricle of the heart were always much higher than those from the right ventricle, and concentrations in the right ventricle were always very close to 700 micrograms/L.