Carbon monoxide and cyanide are highly lethal toxic compounds that can cause significant morbidity and mortality. Smoke inhalation victims present a unique challenge because they can be exposed to both substances. This article will review the most recent literature on carbon monoxide and cyanide diagnostic evaluation and treatment options for each poisoning. Practitioners need to maintain a high index of suspicion to identify and treat carbon monoxide and cyanide poisonings in smoke inhalation victims. Carbon monoxide poisoning can be identified with detection of carboxyhemoglobin levels in blood or bedside co-oximetry. Initial treatment is the administration of 100% normobaric oxygen. Hyperbaric oxygen is a treatment adjunct, although the benefits of this modality are controversial. For cyanide poisoning, there is no quick bedside or laboratory confirmatory test, and it remains a clinical diagnosis. Fire victims with soot in their mouth, altered mental status, and metabolic acidosis with extremely high lactate levels suggest cyanide poisoning. Treatment options are hydroxycobalamin, sodium thiosulfate, and amyl/sodium nitrite. Both hydroxycobalamin and sodium thiosulfate can be given in suspected cyanide and concomitant carbon monoxide poisonings. Amyl and sodium nitrites can cause methemoglobinemia and hypotension and therefore are not recommended if carbon monoxide poisoning is also suspected. Several papers advocate the superiority of hydroxycobalamin due to its quicker onset of action, but to date there exists no well-designed randomized, controlled trial comparing its efficacy to sodium thiosulfate and amyl/sodium nitrite.
— Ann M. Dietrich, MD, Editor