Cyanide and methemoglobin kinetics in smoke inhalation victims treated with the cyanide antidote kit.

STUDY OBJECTIVE: To evaluate serial cyanide, methemoglobin, and carbon monoxide levels in smoke inhalation patients.

SETTING: Regional poison center and regional toxicology treatment center.

PARTICIPANTS: Seven critically ill smoke inhalation patients referred to the regional poison center.

INTERVENTIONS: Peak level and half-life were determined by obtaining serial carboxyhemoglobin, cyanide, and methemoglobin levels.

RESULTS: The mean observed half-life of cyanide was 3.0 +/- 0.6 hours. Methemoglobinemia was evaluated in four patients after sodium nitrite administration. The peak measured methemoglobin levels (mean, 10.5% +/- 2%; range, 7.9% to 13.4%) did not occur until a mean of 50 minutes (range, 35 to 70 minutes) following administration of sodium nitrite. The total oxygen-carrying capacity reduced by the combination of carboxyhemoglobin and methemoglobin was never more than 21% (range, 10% to 21%) in this series.

CONCLUSION: The administration of sodium nitrite to smoke inhalation patients in the presence of concomitant carbon monoxide poisoning may be relatively safe.