26 - Clinical features of Organophosphorous poisoning

*Since organophosphorous compounds are powerful inhibitors of cholinesterase, their poisoning manifests as cholinergic symptoms.

*The clinical features of Organophosphorous poisoning are :

A. MUSCARINIC ACTIONS :
1. Bronchoconstriction and increased bronchial secretion - simulates bronchial asthma. Other symptoms are dyspnea, cough, pulmonary edema and cyanosis.
2. Increased sweating
3. Increased salivation
4. Increased lacrimation - tears may be red
5. Slightly bradycardia
6. Miosis, Blurring/Dimness of vision
7. Increased frequency of micturition and involuntary micturition.
8. Abdominal cramps, diarrhea, epigastric/substernal tightness

B.NICOTINIC ACTIONS :
1. On striated muscles - easy fatigue, fasciculations, cramps, dyspnea (weakness of respiratory muscles and cyanosis)
2. On sympathetic ganglia - Pallor, Occasional elevation of B.P

C. CNS ACTIONS :
1. Restlessness, irritability, apprehension
2. Fine fibrillary tremors of hands, eye lids, tongue
3. Mental confusion, convulsions
4. Coma with absence of reflexes and depression of respiratory and circulatory centres. Death usually occurs due to paralysis of respiratory muscles.

Parikh' Textbook of Medical Jurisprudence Forensic Medicine and Toxicology

19 - organophosphorous poisoning mcqs

1q: a 5 year old child presents with confusion, increased salivation, lacrimation, fasciculations, miosis, tachycardia and hypertension. Which of the following poisons can cause these manifestations ?

a. opium
b. organophosphorous insecticide
c. dhatura
d. organochlorine pesticide

answer b. organophosphorous insecticide

explanation : only opium and organophosphorous insecticides out of the above 4 options cause miosis . it is to be noted that dhatura ( atropine ) and organochlorine cause mydriasis .

organsophosphate poisoning : organophosphate poisons irreversibly inhibit acetylcholinesterase and cause accumulation of acetylcholine at muscarinic and nicotinic receptors .

Muscarinic effects of organosphosphorous poisons are :

1. miosis and blurred vision
2. increased sweating, salivation, lacrimation
3. increased bronchial secretions, bronchoconstriction
4. abdominal cramps, diarrhea, nausea, vomiting
5. urinary frequency and incontinence

Nicotinic effects of organophosphorous poisons are :

1. on striated muscles – twitching, fasciculations, cramps and muscle paralysis
2. on sympathetic ganglia – hypertension and tachycardia

CNS effects of organophosphorous poisons are :

1. anxiety , restlessness and confusion
2. seizures and coma

- this child presents with tachycardia and hypertension which are nicotinic manifestations. Sometimes the presentation can vary due to the muscarinic effect on cardiovascular system which causes bradycardia and hypotension , but this occurs due to severe organosphosphorous poisoning .

This question was asked in the november 2002 AIIMS question paper .