Hydrogen sulfide toxicity
Revision as of 17:26, 6 March 2016 by Neil.m.young (talk | contribs)
Background
General Information
- Colorless, flammable gas
- Encountered in following industries: oil, gas, organic decomposition (sewer and manure), roofing asphalt tanks
- Most common fatal gas exposure
- “Rotten egg” smell which diminishes with high concentrations or prolonged low concentration exposure
- Often used in suicide attempts: acidic detergent (toilet bowl cleaner) is mixed with bath salts or pesticides[1]
Mechanisms of toxicity
- Highly lipid soluble
- Disrupts oxidative phosphorylation by inhibiting cytochrome oxidase aa3 (toxicity through cellular asphyxia and impairs ATP production) => lactate accumulation and metabolic acidosis
- Causes hyperpolarization of potassium-mediated channels in neurons
- Potentiates neuronal inhibitory mechanisms
- Alters brain neurotransmitter content and release
Clinical Features
- Respiratory: dyspnea, cyanosis, hemoptysis, rales, delayed pulmonary edema
- Ophthalmic: conjunctivitis, corneal ulceration, corneal scarring
- Central nervous system: headache, weakness, disequilibrium, intention tremor, muscle rigidity, loss of consciousness, seizures, coma
- Gastrointestinal: green-gray line on gingiva, nausea, vomiting
- Cardiovascular: chest pain, bradycardia
- Neuropsychiatric: amnesia, lack of insight, disorientation, delirium, dementia
- Death
Differential Diagnosis
- Carbon Monoxide Toxicity
- Cyanide Toxicity
- Hydrocarbons Toxicity
- Smoke Inhalation Injury
Diagnosis
- No single test to verify exposure or levels
- ABG Interpretation: metabolic acidosis and normal oxygen saturation (unless pulmonary edema present)
- Elevated lactate
- Discolored copper coins found on patient may be helpful in diagnosis
Management
- Removal from source
- 100% oxygen
- Can give nitrite component of cyanide antidote kit (do NOT give the thiosulfate portion):
- Theoretically increasing methemoglobin formation in blood will cause conversion of sulfide to sulfmethemoglonin (less toxic)
- Amyl nitrite
- Sodium nitrite (3% NaNO2) IV over 2-4 minutes; adult dose 10 mL
- Obtain methemoglobin level 30 minutes after dose (desired level < 30%)
- Hyperbaric oxygen therapy (though not proven to have any benefit)[2]
Disposition
- Admission, likely to MICU
- Toxicology consult