Hydrogen Sulphide (H2S) Flashcards
1
Q
•Hydrogen sulphide (H2S) is
A
- a colorless gas with an irritating odor of rotten eggs.
- It is highly lipid soluble (allowing easy penetration through biological membranes).
2
Q
Sources Of H2S
A
- Bacterial decomposition of proteins (decay of organic matter)
- From mixture involving sulphur acids
- Industrial activities: pulp paper mills, petroleum distillation, leather industry, oil and natural gas production.
3
Q
Mechanism of toxicity
A
•Inhibition of cytochrome oxidase enzyme even with higher affinity than cyanide but spontaneously reversible.
4
Q
Clinical picture Of H2S
A
- Scenario: Unconscious in closed space + odor of rotten eggs
- The primary target organs are CNS & respiratory system.
- CNS :Headache, dizziness, convulsions, and coma.
- Cardiovascular ↓ BP +↑HR + arrhythmia→↓ HR +arrest.
- Gastrointestinal :NV
- Respiratory :Dyspnea, respiratory depression, cyanosis +/- pulmonary edema.
- Dermal Erythema ,cyanosis
- Delayed neuropsychiatric sequelae:
- Memory failure, disorientation, delirium, dementia, transient hearing impairment, visual loss, and anosmia.
- Motor symptoms : ataxia, tremors and muscle rigidity (BG damage)
5
Q
Investigations of H2S
A
1.Arterial blood gases (ABG)
- Blockade of aerobic metabolism. →→metabolic acidosis (elevated lactate)
- Oxygen saturation altered only when respiratory failure occurs.
- Elevated venous oxygen saturation
2.Sulphide determination in the blood not usually rapidly available.
> 0.05 mg /l is considered abnormal.
- Imaging Studies
- Chest x ray: initially may be normal, 20% of patients acute lung injury→ ARDS
- CT scan or MRI delayed findings e.g. basal ganglia lesions
6
Q
Treatment of H2S
A
1.First aid: focus attention to airway patency, ventilation and oxygenation 100% oxygen.
•Removal from site to fresh air
- Antidote:
•Nitrites as methemoglobin inducer to dissociate H2S from cytochrome oxidase
- Specific treatment of complications
7
Q
A
