Hydrogen Sulfide Poisoning

Aka: Hydrogen Sulfide Poisoning, Hydrogen Sulfide Toxicity, Hydrogen Sulfide, Hydrogen Sulfide Gas

1. Background: Hydrogen Sulfide
   1. Hydrogen Sulfide is a Sulfur-Based Toxic Gas
      1. Flammable, colorless gas
      2. Poisonous
      3. Malodorous (rotten egg smell)
      4. Air Pollutant
   2. Manufacturing reagent
      1. Chemical manufacturing
      2. Petroleum processing
      3. Sewage processing
      4. Metallurgy
      5. Agriculture
      6. Analytical Chemistry
   3. Intentional Poisoning (Suicide attempt)
      1. Acid (e.g. toilet bowl cleaner) combined with sulfur-containing molecule (e.g. Pesticides, fungicide, lime sulfur)
      2. Results in release of Hydrogen Sulfide (H2S)
2. Pathophysiology: Hydrogen Sulfide Toxicity
   1. Toxicity
      1. Cytochrome C Oxidase inhibition
      2. Neuronal Potassium channels hyperpolarized
      3. Oxygen radicals form
      4. Corrosive at mucous membranes
   2. Concentrations <100 ppm will be detectable as a rotten egg smell
      1. Prolonged exposure at lower levels may result in loss of olfactory detection
   3. Concentrations >100 ppm result in Loss of Smell by olfactory paralysis (no rotten egg smell detected)
   4. Concentrations >500 ppm are rapidly lethal by inhalation
3. History
   1. Sudden collapse in an enclosed work area such as a sewer (esp. if rotten egg smell was reported)
4. Signs
   1. Ocular ("gas eye")
      1. Conjunctivitis
      2. Photophobia
      3. Lacrimation
   2. Cardiopulmonary
      1. Dyspnea
      2. Cyanosis
      3. Rales
      4. Acute Respiratory Distress Syndrome (ARDS)
   3. Gastrointestinal
      1. Nausea
      2. Vomiting
   4. Neurologic
      1. Headache
      2. Syncope
      3. Loss of consciousness ("Knockdown gas")
      4. Seizures
5. Labs
   1. See Poisoning
   2. Sulfide concentrations
      1. Blood sulfide concentration
      2. Blood and urine thiosulfate concentration
   3. Venous Blood Gas (or Arterial Blood Gas)
      1. Metabolic Acidosis (due to Lactic Acidosis)
6. Imaging
   1. Head MRI or Head CT
      1. As indicated for neurologic findings
7. Management
   1. Immediately remove patient from Hydrogen Sulfide source
      1. Patients may start to improve in open air once removed from source
   2. ABC Management
   3. Respiratory Management
      1. Nonrebreather 100% oxygen
      2. Noninvasive Positive Pressure Ventilation (e.g. BiPap) or Mechanical Ventilation with PEEP
   4. Hypotension management
      1. Intravenous Fluids
      2. Vasopressors
   5. Sulfide Antidotes
      1. Sodium Nitrite 3% 0.2 ml per kg (children) up to 10 ml or 300 mg in adults IV over 2-4 min
      2. Hydroxycobalamin (cyanokit) 2.8 ml/kg or 70 mg/kg (children) up to 200 ml or 5 g in adults over 15 min
         1. May reduce Hydrogen Sulfide Toxicity
         2. Also indicated if co-exposure to Cyanide is suspected
      3. Cobinamide (experimental)
   6. Disposition
      1. Admit all patients with respiratory of neurologic signs or symptoms
      2. Patients with only mild mucosal irritation (e.g. Conjunctivitis) may be discharged home
8. Complications
   1. Neurologic and psychiatric sequelae may be longstanding
9. Resources
   1. Hydrogen Sulfide (OSHA)
      1. https://www.osha.gov/hydrogen-sulfide
   2. Hydrogen Sulfide Toxicity (Stat Pearls)
      1. https://www.ncbi.nlm.nih.gov/books/NBK559264/
10. References
    1. Swadron and Nordt (2022) EM:Rap 22(6): 5-7
    2. Tomaszewski (2017) Crit Dec Emerg Med 31(10): 24