Ver el código de «Hydrogen sulfide toxicity»

==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<ref>Tintinalli et. al. Hydrogen Sulfide. In: Tintinalli et. al. Emergency Medicine A Comprehensive Study Guide. New York, NY: McGraw Hill. 2011. 1320.</ref>
===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==
{{Toxic gas exposure DDX}}

==Evaluation==
*No single test to verify exposure or levels
*[[ABG|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
*[[Hydroxocobalamin]] (Cyanokit)
**5 g over 15 min to start, followed by a second dose PRN
**If given as early as possible, has been shown in animal models to prevent PEA<ref>Haouzi P et al. High-dose hydroxocobalamin administered after H2S exposure counteracts sulfide-poisoning-induced cardiac depression in sheep. Clin Toxicol (Phila). 2015 Jan;53(1):28-36.</ref>
**[[Cobinamide]], a vitamin B12 analog, shows promise as first line for H2S toxicity<ref>Jiang J et al. Hydrogen Sulfide—Mechanisms of Toxicity and Development of an Antidote. Nature. Scientific Reports 6, Article number: 20831 (2016).</ref><ref>Brenner M et al. The vitamin B12 analog cobinamide is an effective hydrogen sulfide antidote in a lethal rabbit model. Clin Toxicol (Phila). 2014 Jun;52(5):490-7.</ref>
*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)<ref>Goldfrank et. al. Hydrogen Sulfide Poisoning. In: Goldfrank et. al. Goldfrank’s Toxicologic Emergencies. New York, NY: McGraw Hill. 2002. 1504-1507. </ref>

==Disposition==
*Admission, likely to MICU
*Toxicology consult

==References==
<references/>

[[Category:Toxicology]]