Cyanide poisoning presents in many forms. Industrial intoxications occur due to extensive use of
cyanide compounds as reaction products.
Smoke inhalation, a polyintoxication, is most often responsible for domestic
cyanide poisonings. Suicidal
poisonings are rare. Cyanogenic compounds may produce acute or subacute toxicity. Signs of
cyanide poisoning include
headache,
vertigo, agitation,
confusion,
coma, convulsions and death. Definitive laboratory confirmation is generally delayed. Elevated plasma
lactate, associated with cardiovascular collapse, should suggest
cyanide intoxication. Immediate treatment includes 100%
oxygen, assisted ventilation, decontamination, correction of
acidosis and blood pressure support. Antidotes include
oxygen,
hydroxocobalamin, di-
cobalt EDTA and methaemoglobin-inducers.
Hydroxocobalamin is an attractive
antidote due to its rapid
cyanide binding and its lack of serious side-effects, even in the absence of
cyanide intoxication.
Sodium thiosulphate acts more slowly than other antidotes and is indicated in subacute
cyanogen poisoning and as an adjunct to acute
cyanide poisoning. Initial evaluation of antidotal efficacy is based on correction of
hypotension and
lactic acidosis; the final analysis rests on the degree of permanent central nervous system injury.