CYANIDE POISONING

  • Sources
    1. Ingestion – chemists, photographers, jewelers, lab techs have access to cyanide salts
    2. Smoke inhalation – release of cyanide from combustion of wool, silk, synthetic rubber
    3. Occupational exposure – many industrial processes involve CN (jewelers, mining, fumigation, photography)
    4. Medicinal sources – nitroprusside
    5. Food sources – pits of apricots, bitter almonds, cherry, peaches
    6. Smoking
  • Pathophys – NO ATP!
    1. Inhibition of cytochrome a3 of ETC –> hydrogen unable to combine with oxygen at terminal end of chain –> no ATP can be made –> cellular hypoxia
  • Clinical presentation
    1. CNS – HA, anxiety, agitation, confusion, lethargy, coma, seizure, “knocked down quickly”
    2. Cardiac – abnormalities of BP and HR
    3. Resp – tachypnea –> bradypnea
    4. Skin – cherry red skin color
  • Diagnosis
    1. Bitter almond smell – only detected by 60% of pop
    2. Severe metabolic acidosis with increased AG and significant lactic acidosis (>7 mmol/L)
    3. VBG looks like ABG
    4. Unexplained coma and acidosis = THINK CYANIDE
  • Tx
    1. Supportive care – ABCs
    2. Cyanide antidote kit
      • Amyl nitrite pearls
        1. Use until IV established
        2. Inhaled for 30 sec to 1 min
        3. Induces about 5% MetHb
      • Sodium nitrite
        1. Peds dose – 0.33 mL/kg
        2. Adult dose – 10 mL
        3. Infuse over 2-4 minutes
        4. Adv effects – vasodilation, hypotension, tachycardia
        5. Induces 7-14% MetHb
      • Sodium thiosulfate
        1. Peds dose: 1.65 mL/kg
        2. Adult dose: 50 mL
      • Mechanisms of kit
        • Nitrite –> methemoglobinemia
          • CN has higher affinity for MetHb
          • MetHb of about 20-30% can be tolerated without sig adv effects
        • Thiosulfate
          • CN transferred from cyanomethemoglobin to thiosulfate –> thiocyanate –> peed out

3. Hydroxocobalamin

      • MOA – chelates CN to form cyanocobalamin (vit B12) –> eliminated in urine
      • Dose
        • 2.5 gm for dilution in 100 cc NS
        • Starting dose
          • Adult – 5 gram (2 vials)
          • Peds – 70 mg/kg
        • Give further doses of 5 gm (up to 15 gm total) recommended for incomplete or transient result
      • To know
        • Red color of hydroxocobalamin –> chromaturia and red skin for up to 2 weeks
        • Interferes with colorimetric lab tests; if given pre-hospital, EMS should draw labs first
        • Do not give in same IV as thiosulfate

4. So if concomitant CO and CN poisoning:

      • Do not have nitrites – CO poisoning + MetHb = BADNESS
      • Suggested mgmt
        • Sodium thiosulfate +/- hydroxocobalamin
        • HBO
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Jay Khadpe MD

  • Editor in Chief of "The Original Kings of County"
  • Assistant Professor of Emergency Medicine
  • Assistant Residency Director
  • SUNY Downstate / Kings County Hospital

Latest posts by Jay Khadpe MD (see all)


Jay Khadpe MD

  • Editor in Chief of “The Original Kings of County”
  • Assistant Professor of Emergency Medicine
  • Assistant Residency Director
  • SUNY Downstate / Kings County Hospital

1 Comment

Mark Silverberg · March 30, 2012 at 11:24 pm

Excellent reviews. Remember too that the CO-Hgb will alter your pulse ox reading making it unreliable. It alters the light absorption of regular hemoglobin. In the CO poisoned pt it should gravitate towards 85-87%.

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