Cyanide Toxicity Workup

  • Author: Inna Leybell, MD; Chief Editor: Asim Tarabar, MD   more...
 
Updated: Nov 1, 2011
 

Approach Considerations

Arterial and venous blood gases

Metabolic acidosis, often severe, combined with a reduced arterial-venous oxygen saturation difference (< 10%) suggests diagnosis. Apnea may result in combined metabolic and respiratory acidosis.

Blood lactate level

A plasma lactate concentration of greater than 10 mmol/L in smoke inhalation or greater than 6mmol/L after reported or strongly suspected pure cyanide poisoning suggests significant cyanide exposure.

Red blood cell and plasma cyanide concentration

Cyanide blood concentrations are not generally available in time to aid in the treatment of acute poisoning. In cyanogen exposures, these tests provide documentation for therapeutic use, which may last several days.

Blood cyanide concentrations may artificially increase after sodium nitrite (antidote) administration, because of in vitro release of cyanide from cyanomethemoglobin during the analytical procedure by strong acid used in analysis.

Carboxyhemoglobin level

Carboxyhemoglobin (HbCO) level (by co-oximetry) or blood carbon monoxide concentration (by infrared spectroscopy) may be obtained in patients with smoke inhalation to rule out concurrent exposure. HbCO measurements may be artificially elevated in blood samples drawn after hydroxocobalamin administration.[5]

Evaluation of metabolic acidosis

Blood concentrations of methanol, ethylene glycol, iron, ketones, and salicylates may be useful in the evaluation of unexplained metabolic acidosis. Pending results should not delay the treatment if cyanide exposure is suspected.

Methemoglobin level

Methemoglobin concentrations provide a guide for continued therapy after the use of methemoglobin-inducing antidotes, such as sodium nitrite.

The presence of methemoglobin suggests little or no free cyanide for binding because methemoglobin vigorously binds cyanide to form cyanomethemoglobin (not measured as methemoglobin).

Elevated levels of methemoglobin (>10%) indicate that further nitrite therapy is not indicated and, in fact, may be dangerous.

Imaging studies

No imaging studies are indicated acutely for cyanide exposure, but magnetic resonance imaging (MRI) may be useful during the evaluation of postexposure neurologic sequelae.

Electrocardiography

Electrocardiography may show nonspecific changes, including the following[6] :

  • Atrioventricular blocks
  • Supraventricular or ventricular arrhythmias
  • Ischemic electrocardiographic changes and eventual asystole
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Contributor Information and Disclosures
Author

Inna Leybell, MD  Clinical Assistant Professor, Department of Emergency Medicine, NYU Langone Medical Center

Inna Leybell, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Student Association/Foundation, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Coauthor(s)

Stephen W Borron, MD, MS, FAAEM, FACEP, FAACT, FACMT  Professor of Emergency Medicine and Medical Toxicology, Division of Medical Toxicology, Department of Emergency Medicine, Paul L Foster School of Medicine, Texas Tech University Health Sciences Center; Associate Medical Director, West Texas Regional Poison Center

Stephen W Borron, MD, MS, FAAEM, 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, American College of Occupational and Environmental Medicine, American Industrial Hygiene Association, and European Association of Poisons Centres and Clinical Toxicologists

Disclosure: Meridian Pharmaceuticals Consulting fee Consulting

Carlos J Roldan, MD, FAAEM  Assistant Professor, Department of Emergency Medicine, University of Texas Health Science Center at Houston Medical School; Consulting Staff, Department of Emergency Medicine, Memorial Hermann Hospital and Lyndon Baines General Hospital

Carlos J Roldan, MD, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American Pain Society, American Society of Regional Anesthesia and Pain Medicine, International Association for the Study of Pain, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Chief Editor

Asim Tarabar, MD  Assistant Professor, Director, Medical Toxicology, Department of Emergency Medicine, Yale University School of Medicine; Consulting Staff, Department of Emergency Medicine, Yale-New Haven Hospital

Disclosure: Nothing to disclose.

Additional Contributors

Frederic J Baud, MD Director, Professor, Toxicological and Medical Intensive Care Unit, Hôpital Lariboisiere of Paris, France

Disclosure: Nothing to disclose.

John G Benitez, MD, MPH, FACMT, FAACT, FACPM, FAAEM, Associate Professor, Department of Medicine, Medical Toxicology, Vanderbilt University Medical Center; Managing Director, Tennessee Poison Center

John G Benitez, MD, MPH, FACMT, FAACT, FACPM, FAAEM, is a member of the following medical societies: American Academy of Clinical Toxicology, American Academy of Emergency Medicine, American College of Medical Toxicology, American College of Preventive Medicine, Society for Academic Emergency Medicine, Undersea and Hyperbaric Medical Society, and Wilderness Medical Society

Disclosure: Nothing to disclose.

Robert S Hoffman, MD, FAACT, FACMT Associate Professor, Departments of Emergency Medicine and Medicine, Clinical Pharmacology, New York University School of Medicine, Consulting Staff, Department of Emergency Services, Bellevue and New York University Hospital

Robert S Hoffman, MD, 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, American College of Physicians, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

David C Lee, MD Research Director, Department of Emergency Medicine, Associate Professor, North Shore University Hospital and New York University Medical School

David C Lee, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American College of Medical Toxicology, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

John T VanDeVoort, PharmD Regional Director of Pharmacy, Sacred Heart & St. Joseph's Hospitals

John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists

Disclosure: Nothing to disclose.

References

  1. Akyildiz BN, Kurtoglu S, Kondolot M, Tunc A. Cyanide poisoning caused by ingestion of apricot seeds. Ann Trop Paediatr. 2010;30(1):39-43. [Medline].

  2. National Cancer Institute. Cancer topics: Laetrile/Amygdalin. 11/21/2005;[Full Text].

  3. Bronstein AC, Spyker DA, Cantilena LR Jr, Green JL, Rumack BH, Heard SE. 2007 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 25th Annual Report. Clin Toxicol (Phila). Dec 2008;46(10):927-1057. [Medline]. [Full Text].

  4. Bronstein AC, Spyker DA, Cantilena LR Jr, Green JL, Rumack BH, Giffin SL. 2008 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 26th Annual Report. Clin Toxicol (Phila). Dec 2009;47(10):911-1084. [Medline].

  5. Lee J, Mukai D, Kreuter K, et al. Potential interference by hydroxocobalamin on co-oximetry hemoglobin measurements during cyanide and smoke inhalation treatments. Ann Emerg Med. 2007;49(6):802-805. [Medline].

  6. Fortin JL, Desmettre T, Manzon C, Judic-Peureux V, Peugeot-Mortier C, Giocanti JP, et al. Cyanide poisoning and cardiac disorders: 161 cases. J Emerg Med. May 2010;38(4):467-76. [Medline].

  7. 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].

  8. Borron SW, Baud FJ, Barriot P, Imbert M, Bismuth C. Prospective study of hydroxocobalamin for acute cyanide poisoning in smoke inhalation. Ann Emerg Med. Jun 2007;49(6):794-801, 801.e1-2. [Medline].

  9. Bebarta VS, Tanen DA, Lairet J, Dixon PS, Valtier S, Bush A. Hydroxocobalamin and sodium thiosulfate versus sodium nitrite and sodium thiosulfate in the treatment of acute cyanide toxicity in a swine (Sus scrofa) model. Ann Emerg Med. 2010;55(4):345-51. [Medline].

  10. Curry SC, Connor DA, Raschke RA. Effect of the cyanide antidote hydroxocobalamin on commonly ordered serum chemistry studies. Ann Emerg Med. Jul 1994;24(1):65-7. [Medline].

  11. Sutter M, Tereshchenko N, Rafii R, Daubert GP. Hemodialysis Complications of Hydroxocobalamin: A Case Report. J Med Toxicol. Mar 30 2010;[Medline].

  12. Hall AH, Saiers J, Baud F. Which cyanide antidote?. Crit Rev Toxicol. 2009;39(7):541-52. [Medline].

 
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