IM22.7 | Phosphide Poisoning — Summary & Reflection

KEY TAKEAWAYS

Aluminium phosphide (AlP/Celphos) and zinc phosphide poisoning:

• Mechanism: AlP + H₂O → PH₃ (phosphine gas); phosphine inhibits cytochrome c oxidase (Complex IV) and other ETC complexes → ATP depletion + oxidative membrane damage; irreversible mitochondrial injury; NO specific antidote
• Clinical features: vomiting (garlic/fishy odour), epigastric pain (0–4 hours) → tachycardia, hypotension, arrhythmias (4–12 hours) → refractory shock, ARDS, multi-organ failure (12–24+ hours); metabolic acidosis (lactic acidosis)
• Why heart is primary target: highest mitochondrial density + no anaerobic reserve → energy failure causes contractility loss, arrhythmias, cardiomyocyte death
• Investigations: ABG (pH, lactate — most important severity markers), serial ECG (arrhythmia monitoring), serum electrolytes, echo (LV function), CXR
• Poor prognosis markers: >1 tablet ingested, pH < 7.2, lactate > 8 mmol/L, early cardiovascular collapse, VT/VF on ECG
• Management: NO antidote; aggressive supportive care — IV fluids + vasopressors (noradrenaline), mechanical ventilation, sodium bicarbonate for pH < 7.1, anti-arrhythmics, IABP/mechanical circulatory support in refractory cardiogenic shock; NO gastric lavage routinely; coconut oil early (observational evidence only)
• Prognosis: Case fatality rate 60–90% for 2+ tablets; honest early family counselling is mandatory
• Zinc phosphide: identical mechanism, lower potency per gram, somewhat better prognosis

REFLECT

The farmer in the opening hook represents one of the most challenging situations a young doctor will face: a patient who is rapidly dying, no antidote exists, and the family is in the room asking what you are doing to save their son. How do you have that conversation — at 3 am, in a district hospital, in the farmer's local language — honestly, compassionately, and without abandoning clinical rigour? Think about how you would explain the concept of 'no antidote' to a family who believes that hospitals have medicines for every problem. Think about how you would balance vigorous resuscitation (which can extend the time window for potential recovery) with honest prognostication (which allows the family to prepare). Aluminium phosphide poisoning is not just a toxicology case — it is a test of communication, humanity, and clinical honesty under pressure. The physicians who navigate it best are those who understand both the biochemistry and the humanity of what they are witnessing.