Suspected cyanide poisoning in smoke inhalation: complications of sodium nitrite therapy

A 78 year old man was found comatose, apneic, and asystolic after closed-space smoke inhalation. He was successfully resuscitated to pulse and blood pressure at the scene. A cyanide component to the poisoning was suspected and two 300 mg doses of sodium nitrite were administered, resulting in significant hypotension. Although high methemoglobin levels were not induced, when added to simultaneously obtained carboxyhemoglobin levels, the total amount of non-oxygen transporting hemoglobin remained nearly constant for about 4-1/2 hours before hyperbaric oxygen (HBO) therapy could be administered. The patient later died in multi-organ system failure. Admission whole blood cyanide level was only 0.34 mcg/mL. These sodium nitrite adverse effects can be avoided by slow intravenous infusion and by administering only recommended doses. In smoke inhalation victims with suspected cyanide poisoning, sodium thiosulfate should be administered first, and sodium nitrite withheld until after the patient is receiving HBO therapy. When available, hydroxocobalamin (which neither induces methemoglobinemia nor causes hypotension) may be the specific cyanide antidote of choice for victims of smoke inhalation.