A patient arrives to your ED who was involved in a house fire. EMS states that the patient made it outside when he realized his dog was still in his room. He ran back into the heavily involved home & emerged 1 minute later, alert, but coughing. The patient has no external burns, no evidence of singed facial/nasal hair, & the airway appears clear. After an initial assessment, the patient becomes altered & complains of dizziness. What is a major consideration that is often overlooked? Cyanide poisoning.
That’s right, cyanide poisoning doesn’t just occur to spies in the movies, but is actually a direct product of burning polymers &vinyl…ie. carpet & furniture. Cyanide poisoning is quite serious & will kill a patient in mere minutes if not addressed. Antidotes used to consist of a multi-step process of inhalants & IV drugs, but now is mainly treated with just one… Hydroxocobalamin! Hydroxocobalamin is the natural form of B12 & to understand why a precursor to B12 is an antidote, we must first explore how cyanide poisoning works.
Cyanide inhibits cytochrome oxidase & ATP production, which ceases aerobic cellular respiration (the use of oxygen). If cells cannot use oxygen, then they must begin anerobic (non-oxygen) metabolism. This results in lactate production, hypoxia & acidosis, which if allowed to continue, will result in death.
Hydroxocobalamins role is in its ability for each of its ions to directly bind to cyanide ions & convert it to cyanocobalamin, which is much less toxic & is excreted by the kidneys forming one of its well-known side effects, dark red urine.
Other SE include hypertension, red skin & secretions, nausea, vomiting & headache…but hey its better than death.
Today the most common way to give the Antidote is in the commercially available Cyanokit. The dark red medication consists of two glass vials that must be constituted with 100ml NS & given over 7.5 minutes each.
Some facilities still use the old kits of inhaled Amyl nitrate, followed by IV sodium nitrite, finally followed by IV sodium thiosulfate but the complexity of this administration has led to wide adoption of the Cyanokit, especially by prehospital providers!