The International Programme on Chemical Safety (IPCS)—a cooperative program of the World Health Organization (WHO), the International Labour Organization (ILO), and the United Nations Environment Programme (UNEP)—designates cyanide a priority chemical in relation to the potential impact on human health and the environment. Like other IPCS priority chemicals, cyanide is highly toxic, is a transboundary safety concern, is a target for risk management in multiple countries, is produced in large quantities, has dispersive use, and poses a risk for human exposure (Table 1). Acute exposure to cyanide has caused significant morbidity and mortality in household and industrial accidents, as well as in suicides and attempted genocides, wars, and acts of terrorism. The most common, but perhaps least recognized source of cyanide in cases of acute poisoning is from smoke caused by fires. This review is the product of a collaboration among experts in prehospital emergency medicine, public health and safety, and disaster preparedness. Current understanding of the causes, consequences, and management of cyanide poisoning are described as a potential advancement in antidotal therapy that could transform the provision of prehospital care to cyanide-poisoned victims.

Effective management of cyanide poisoning from chemical terrorism, inhalation of fire smoke, and other causes constitutes a critical challenge for the pre-hospital care provider. The ability to meet the challenge of managing cyanide poisoning in the prehospital setting may be enhanced by the availability of the cyanide antidote hydroxocobalamin, currently under development for potential introduction in the United States. This paper discusses the causes, recognition, and management of acute cyanide poisoning in the prehospital setting with emphasis on the emerging profile of hydroxocobalamin, an antidote that may have a risk:benefit ratio suitable for empiric, out-of-hospital treatment of the range of causes of cyanide poisoning. If introduced in the US, hydroxocobalamin may enhance the role of the US prehospital responder in providing emergency care in a cyanide incident.

The contribution of smoke inhalation to cyanide-attributed morbidity and mortality arguably surpasses all other sources of acute cyanide poisoning. Research establishes that cyanide exposure is: (1) to be expected in those exposed to smoke in closed-space fires; (2) cyanide poisoning is an important cause of incapacitation and death in smoke-inhalation victims; and (3) that cyanide can act independently of, and perhaps synergistically with, carbon monoxide to cause morbidity and mortality. Effective prehospital management of smoke inhalation-associated cyanide poisoning is inhibited by: (1) a lack of awareness of fire smoke as an important cause of cyanide toxicity; (2) the absence of a rapidly returnable diagnostic test to facilitate its recognition; and (3) in the United States, the current unavailability of a cyanide antidote that can be used empirically with confidence outside of hospitals. Addressing the challenges of the prehospital management of smoke inhalation-associated cyanide poisoning entails: (1) enhancing the awareness of the problem among prehospital responders; (2) improving the ability to recognize cyanide poisoning on the basis of signs and symptoms; and (3) expanding the treatment options that are useful in the prehospital setting.

The potential for domestic or international terrorism involving cyanide has not diminished and in fact may have increased in recent years. This paper discusses cyanide as a terrorist weapon and the current state of readiness for a cyanide attack in the United States. Many of the factors that render cyanide appealing to terrorists are difficult to modify sufficiently to decrease the probability of a cyanide attack. For example, the relative ease with which cyanide can be used as a weapon without special training, its versatile means of delivery to intended victims, and to a large degree, its ready availability cannot be significantly modified through preparedness efforts. On the other hand, the impact of an attack can be mitigated through preparedness measures designed to minimize the physical, psychological, and social consequences of cyanide exposure. Although the nation remains ill-equipped to manage a cyanide disaster, significant progress is being realized in some aspects of preparedness. Hydroxocobalamin—a cyanide antidote that may be appropriate for use in the prehospital setting for presumptive cases of cyanide poisoning—currently is under development for potential introduction in the US. If it becomes available in the US, hydroxocobalamin could enhance the role of the prehospital emergency responder in providing care to victims of a cyanide disaster. Additional progress is required in the areas of ensuring local and regional availability of antidotal treatment and supportive interventions, educating emergency healthcare providers about cyanide poisoning and its management, and raising public awareness of the potential for a cyanide attack and how to respond.