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Cyanide

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Poisoning can occur from. Occupation, accidental ingestion of pre-metabolites ... Biochemical Toxicology. Inhibits final step of oxydative phosphorylation ... – PowerPoint PPT presentation

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Title: Cyanide


1
Cyanide
  • By Jack Hay
  • 3/2/06

2
Introduction
  • Potent cellular toxin with nefarious history
  • Poisoning can occur from
  • Occupation, accidental ingestion of
    pre-metabolites
  • Sodium nitroprusside infusion
  • Cyanogenic glycoside plant ingestion
  • Inhalation of burning plastics

3
Sources of Exposure
  • Industrial
  • Hydrogen cyanide gas and cyanide salts
  • Smoke inhalation
  • Fires or Burning of vinyl or wool
  • Chronic
  • Workers have higher thyroid dz and B12 deficiency
  • Other
  • Suicides, homicides, acetonitrile-containing
    cosmetics

4
Sources of Biodegradation
5
Biochemical Toxicology
  • Inhibits final step of oxydative phosphorylation
  • Pyruvate ? lactate (anaerobically) ? severe
    metabolic acidosis
  • Alters calcium homeostasis
  • Constricts pulmonary and coronary vessels

6
Clinical Time CourseRoutes of Exposure
  • Inhalation ? immediate symptoms
  • Ingestion ? within minutes
  • Delayed if requires metabolic activation
  • Acetonitrile nail remover releases HCN after
    hepatic oxidative metabolism

7
Did I Just Take Cyanide?
8
Cyanide Clinical Features
  • History
  • Watch for delayed toxicity with ingestion
  • CNS
  • Headache
  • Drowsiness
  • Seizures
  • Coma

9
Cyanide Clinical Features
  • Cardiovascular
  • Tachycardia
  • HTN
  • Collapse/asystole
  • Pulmonary
  • Dyspnea
  • Tachypnea
  • Apnea

10
Cyanide Clinical Features
  • Smell of bitter almonds on exam
  • Laboratory
  • Severe metabolic acidosis
  • Absence of met acidosis precludes cyanide
    toxicity
  • Toxic levels correlate with lactate levels gt 10
    mmol/L independent of CO level
  • in smoke inhalation

11
Differential Diagnosis
  • Consider in a poisoned pt with normal Pao2 and
    high anion gap metabolic acidosis

12
Cyanide Tanks in Brooklyn Mines, CA
13
Treatment
  • Antidote kit
  • Amyl nitrate ampule (for inhalation)
  • Sodium nitrite 3
  • 10mL (300mg)
  • Sodium thiosulfate 25
  • 50mL (12.5g)

14
Nitrites
  • Methemoglobin-formation ability may not be the
    key to their effectiveness
  • Side effects include hypotension
    methemoglobinemia
  • Adjust pediatric dose according to hemoglobin
    level

15
Sodium Thiosulfate
  • Given after nitrite
  • Enhances enzymatic thiocyanate formation
  • Form of cyanide excreted by kidneys
  • Limited toxicity makes it safe empirically
  • Helpful as sole inhalation therapy where
    subsequent CO exposure is of concern

16
Oxygen
  • Enhances therapeutic efficacy of antidotes
  • Hyperbaric oxygen works only with concomittant CO
    poisoning

17
Other Therapies
  • Dicobalt edetate (Kelocyanor)
  • First line in UK
  • Toxicity great if cyanide not present
  • DMAP
  • German alternative
  • Hydroxocobalamin (Vit B12a)
  • Choice in France
  • Used in combination with sodium thiosulfate

18
Supportive Care
  • 100 oxygen by mask
  • Cardiac monitoring
  • IV line placement
  • Treat hypotension with IVF and pressors
  • Treat seizures with benzodiazepines

19
Decontamination
  • Gastric lavage/charcoal AFTER resuscitation
  • Topical exposures require copious water irrigation

20
Cyanide Carboxyhemoglobin
  • Hypotension in a bradycardic, comatose patient is
    not a contraindication for sodium nitrite
  • Empiric nitrite administration to patients with
    elevated carboxyhemoglobin, however, is
    relatively contraindicated
  • Potential for methemoglobinemia which further
    decreases oxygen-carrying capacity

21
Laboratory Evaluation
22
Laboratory Evaluation
  • ABG (confirm gap metabolic acidosis)
  • Check for carboxyhemoglobin
  • Cant wait for other tests before treating
  • Whole-blood cyanide can be tested for later
    review
  • Fatal at gt 2.5 mcg/mL
  • Serum lactate gt 10 mmol/L in smoke inhalation
    correlates with cyanide toxicity

23
Disposition
  • ADMIT if treated with antidote
  • ADMIT if chance for delayed presentation
  • ADMIT for cardiac monitoring
  • ADMIT for risk of cardiac arrest
  • ADMIT you slept through this lecture

24
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