In acute organophosphorus poisoning, death is most often due to which mechanism?

• A. Respiratory arrest
• B. Cardiac failure
• C. Diaphragmatic failure
• D. Hepatic failure

Answer: (C)

In acute organophosphorus poisoning the crucial event is inhibition of acetylcholinesterase, which causes an excess of acetylcholine at neuromuscular junctions. This leads to overstimulation of nicotinic receptors on skeletal muscles, producing weakness and eventual paralysis of the diaphragm and other respiratory muscles. When the diaphragm cannot contract effectively, ventilation collapses, causing respiratory failure and death. While cardiac effects and other organ problems can occur, they are not the primary immediate cause of death; death most often results from diaphragmatic (respiratory muscle) failure that leads to respiratory arrest unless ventilatory support is provided.