To obtain emergency consultation with a medical toxicologist, in the United States, call 1-800-222-1222 for the nearest regional poison control center. Contact information for poison control centers around the world is available at the WHO website and in the UpToDate topic on regional poison control centers (society guideline links). |
General information |
Cyanide poisoning is rapidly lethal unless treated with antidote |
Clinical features |
History |
Ascertain if patient has access to cyanide, or if patient was part of a high-risk event (eg, fire, industrial exposure) |
Initial symptoms are nonspecific: headache, anxiety, confusion, abdominal pain |
Physical examination |
Vital signs: initial hypertension/tachycardia/tachypnea progresses to respiratory and circulatory collapse |
Skin: may be flushed with "cherry red" color |
Neurologic: seizures and coma as poisoning progresses |
Laboratory evaluation |
Obtain the following: |
Fingerstick glucose, acetaminophen and salicylate levels, electrocardiogram, and pregnancy test (when appropriate) |
Basic chemistries and serum lactate - Elevated anion gap acidosis, with elevated lactate, expected in cyanide poisoning
- Venous blood appears bright red
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Central venous blood gas with concomitant arterial blood gas - Narrowed venous-arterial PO2 gradient supports cyanide toxicity
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Carboxyhemoglobin and methemoglobin levels - Rule out dyshemoglobinemias
- Use nitrites (refer below) cautiously or not at all in presence of dyshemoglobinemias
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Cyanide poisoning can cause: renal failure, hepatic failure, rhabdomyolysis, pulmonary edema; obtain relevant studies as indicated |
General treatment |
Secure airway, breathing, and circulation. Intubation is usually required. Administer high-flow oxygen by nonrebreather face mask regardless of pulse oximetry reading. |
Do NOT perform mouth to mouth resuscitation in cases of suspected cyanide toxicity. Patients with dermal exposure must be decontaminated using proper precautions. |
Give a single dose of activated charcoal if the airway is adequately protected (50 g in adults; 1 g/kg in children with maximum dose of 50 g) |
Treat hypotension with rapid IV boluses of isotonic fluid and vasopressors as needed. Treat seizures with a benzodiazepine (eg, diazepam 5 mg IV). |
Obtain assistance from medical toxicologist or poison control center |
Antidotal treatment |
Administer cyanide antidote when cyanide poisoning is clinically suspected. Hydroxocobalamin is the preferred antidote. |
If hydroxocobalamin is available, give the following: - Hydroxocobalamin 70 mg/kg up to 5 g IV (5 g is standard adult dose)
- Sodium thiosulfate (25%): 1.65 mL/kg up to 50 mL IV; may repeat once (maximum dose 12.5 g)
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If hydroxocobalamin is not available, cyanide toxicity is known or strongly suspected, and there are no contraindications to nitrites, give the following: - Sodium nitrite 10 mg/kg – up to 300 mg – by slow IV infusion; may repeat once
- Sodium thiosulfate (25%) 1.65 mL/kg up to 50 mL IV; may repeat once
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If hydroxocobalamin is not available and cyanide toxicity is possible but not certain, or the patient has contraindications to nitrites, give the following: - Sodium thiosulfate (25%) 1.65 mL/kg up to 50 mL IV; may repeat once
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Refer to UpToDate topic for details about nitrite treatment for children and patients with anemia, and for treatment in cases of unlikely cyanide poisoning |