Hydrogen Cyanide Poisoning Clinical Presentation

  • Author: Lewis S Nelson, MD, FACEP, FAACT, FACMT; Chief Editor: Robert G Darling, MD, FACEP   more...
 
Updated: Dec 9, 2011
 

History

Key historical features for suspected hydrogen cyanide (HCN) casualties include onset, severity, and time course of symptoms; time, nature, and route of exposure; presence of smoke; odors and colors of gas; effects on surroundings (eg, dead animals or other human casualties); and evidence of exposure to other chemicals or coingestants. As many as 50% of patients exposed to cyanide may describe an odor of bitter almonds.[12, 11]

Symptoms after exposure to high vapor concentrations may include the following:

  • Transient hyperpnea and hypertension 15 seconds after inhalation
  • Convulsions in 30-45 seconds
  • Loss of consciousness in 30 seconds
  • Respiratory arrest in 3-5 minutes
  • Bradycardia, hypotension, and cardiac arrest within 5-8 minutes of exposure

Symptoms after exposure to lower vapor concentrations or after ingestion or liquid exposure may include the following:

  • Delayed onset of symptoms of several minutes
  • Feelings of apprehension or anxiety
  • Vertigo
  • Feeling of weakness
  • Nausea, with or without vomiting
  • Muscular trembling
  • Loss of consciousness
  • Headache
  • Dyspnea

Patients exposed to cyanogen chloride experience severe eye and mucous membrane irritation.[13] Low-dose exposure results in rhinorrhea, bronchorrhea, and lacrimation. Inhalational exposure results in dyspnea, cough, and chest discomfort. Exposure to nitriles (acetonitrile and/or propionitrile) may be associated with a significant delay in onset of symptoms.

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Physical Examination

Physical findings are nonspecific and are similar to those of severe hypoxemia, including the following:

  • Altered mental status
  • Bradypnea followed by apnea
  • Cardiac dysrhythmias followed by cardiac arrest
  • Convulsions
  • Hypotension
  • Transient hyperpnea

Classically, the skin of a cyanide-poisoned patient is described as cherry red in color due to elevated venous oxygen content resulting from failure of tissues to extract oxygen. In addition, arterialization of the venous blood may also be noted during phlebotomy or examination of the retinal veins. Alternatively, patients may be cyanotic after prolonged respiratory failure and shock. Despite its name, cyanosis is not a prominent finding of cyanide poisoning.

Patients may demonstrate diaphoresis with normal or dilated pupils. Initial hypertension and compensatory bradycardia are followed by hypotension and tachycardia. Terminal hypotension is accompanied by bradyarrhythmias before asystole.

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Contributor Information and Disclosures
Author

Lewis S Nelson, MD, FACEP, FAACT, FACMT  Associate Professor, Department of Emergency Medicine, New York University School of Medicine; Attending Physician, Department of Emergency Medicine, Bellevue Hospital Center, New York University Medical Center and New York Harbor Healthcare System

Lewis S Nelson, MD, FACEP, FAACT, FACMT is a member of the following medical societies: American Academy of Clinical Toxicology, American College of Emergency Physicians, American College of Medical Toxicology, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Colleen M Rivers, MD  Senior Fellow in Medical Toxicology, New York City Poison Control Center, Bellevue Hospital Center

Disclosure: Nothing to disclose.

Erik D Schraga, MD  Staff Physician, Department of Emergency Medicine, Mills-Peninsula Emergency Medical Associates

Disclosure: Nothing to disclose.

Andre Pennardt, MD, FACEP, FAAEM, FAWM  Clinical Associate Professor of Emergency Medicine, Medical College of Georgia; Assistant Professor of Military and Emergency Medicine, Uniformed Services University of the Health Sciences; Consulting Staff, Departments of Emergency Medicine, Aviation Medicine and Dive Medicine, Womack Army Medical Center

Andre Pennardt, MD, FACEP, FAAEM, FAWM is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, Association of Military Surgeons of the US, International Society for Mountain Medicine, National Association of EMS Physicians, Special Operations Medical Association, and Wilderness Medical Society

Disclosure: Nothing to disclose.

Chief Editor

Robert G Darling, MD, FACEP  Adjunct Clinical Assistant Professor of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, F Edward Hebert School of Medicine; Associate Director, Center for Disaster and Humanitarian Assistance Medicine

Robert G Darling, MD, FACEP is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, American Telemedicine Association, and Association of Military Surgeons of the US

Disclosure: Nothing to disclose.

Additional Contributors

Rick Kulkarni, MD Attending Physician, Department of Emergency Medicine, Cambridge Health Alliance, Division of Emergency Medicine, Harvard Medical School

Rick Kulkarni, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: WebMD Salary Employment

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Suzanne White, MD Medical Director, Regional Poison Control Center at Children's Hospital, Program Director of Medical Toxicology, Associate Professor, Departments of Emergency Medicine and Pediatrics, Wayne State University School of Medicine

Suzanne White, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Clinical Toxicology, American College of Epidemiology, American College of Medical Toxicology, American Medical Association, and Michigan State Medical Society

Disclosure: Nothing to disclose.

References

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  2. Greenfield RA, Brown BR, Hutchins JB. Microbiological, biological, and chemical weapons of warfare and terrorism. Am J Med Sci. Jun 2002;323(6):326-40. [Medline].

  3. Rosenbloom M, Leikin JB, Vogel SN. Biological and chemical agents: a brief synopsis. Am J Ther. Jan-Feb 2002;9(1):5-14. [Medline].

  4. Baskin SI, Brewer TG. Cyanide poisoning. In: Medical Aspects of Chemical and Biological Warfare. 1997:271-286.

  5. Morocco AP. Cyanides. Crit Care Clin. Oct 2005;21(4):691-705, vi. [Medline].

  6. Sidell FR, Patrick WC, Dashiell TR. Cyanide. In: Jane's Chem-Bio Handbook. 1998:79-88.

  7. USACHPPM. Cyanide. In: USACHPPM Tech Guide 244: The Medical NBC Battlebook. 1999:V-36-37.

  8. Burda AM, Sigg T. Pharmacy preparedness for incidents involving weapons of mass destruction. Am J Health Syst Pharm. Dec 1 2001;58(23):2274-84. [Medline].

  9. Lynch EL, Thomas TL. Pediatric considerations in chemical exposures: are we prepared?. Pediatr Emerg Care. Mar 2004;20(3):198-208. [Medline].

  10. Baud FJ, Borron SW, Megarbane B. Value of lactic acidosis in the assessment of the severity of acute cyanide poisoning. Crit Care Med. Sep 2002;30(9):2044-50. [Medline].

  11. Musshoff F, Schmidt P, Daldrup T. Cyanide fatalities: case studies of four suicides and one homicide. Am J Forensic Med Pathol. Dec 2002;23(4):315-20. [Medline].

  12. Brennan RJ, Waeckerle JF, Sharp TW. Chemical warfare agents: emergency medical and emergency public health issues. Ann Emerg Med. Aug 1999;34(2):191-204. [Medline].

  13. Department of the Army. Blood agents (Cyanogens). In: Field Manual 8-285: Treatment of Chemical Agent Casualties and Conventional Military Chemical Injuries. 1995:VI-1-2.

  14. USAMRICD. Cyanide. In: Field Management of Chemical Casualties Handbook. 1996:37-40.

  15. USAMRICD. Cyanide. In: Medical Management of Chemical Casualties Handbook. 1999:38-58.

  16. Kirk MA, Gerace R, Kulig KW. Cyanide and methemoglobin kinetics in smoke inhalation victims treated with the cyanide antidote kit. Ann Emerg Med. Sep 1993;22(9):1413-8. [Medline].

  17. Borron SW, Baud FJ, Mégarbane B, Bismuth C. Hydroxocobalamin for severe acute cyanide poisoning by ingestion or inhalation. Am J Emerg Med. Jun 2007;25(5):551-8. [Medline].

  18. Martin CO, Adams HP. Neurological aspects of biological and chemical terrorism: a review for neurologists. Arch Neurol. Jan 2003;60(1):21-5. [Medline].

 
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