Best indicator for beneficial effect of atropine in a patient with organophosphorous poisoning is: March 2012
**Question:** Best indicator for beneficial effect of atropine in a patient with organophosphorous poisoning is: March 2012
**Core Concept:**
Organophosphorus (OP) compounds are a class of chemicals that act as insecticides, and they inhibit the enzyme acetylcholinesterase (AChE), causing an excess of acetylcholine (ACh) at the neuromuscular junction and synaptic cleft. This leads to overstimulation of post-synaptic neurons, resulting in symptoms like increased salivation (sialorrhea), bronchorrhea (increased bronchial secretions), bronchoconstriction, hypertension, tachycardia, and respiratory failure. Atropine is a competitive antagonist of ACh at the muscarinic receptors, preventing the excess ACh from binding and reducing its effects.
**Why the Correct Answer is Right:**
Atropine is a valuable pharmacological agent in managing organophosphorus poisoning, as it helps counteract the effects of excess acetylcholine. In March 2012, the most appropriate indicator of its beneficial effect is the measurement of plasma AChE activity.
**Why Each Wrong Option is Incorrect:**
A. Salivary secretion: While salivation is a symptom of OP poisoning, measuring saliva output does not directly indicate the effectiveness of atropine treatment.
B. Bradycardia: Bradycardia (slow heart rate) is a side effect of atropine rather than a measure of its effectiveness.
C. Pupillary dilation: Assessing pupillary size does not directly evaluate atropine's impact on OP poisoning management.
D. Respiratory rate: Changes in respiratory rate may not accurately reflect atropine's effectiveness, as it can mask the respiratory depression caused by OP poisoning.
**Clinical Pearl:**
The measurement of plasma AChE activity is crucial for evaluating the effectiveness of atropine in OP poisoning management, as it directly indicates the inhibition of AChE, which is the primary target of OP compounds and the primary action of atropine. Ensuring a reduction in plasma AChE activity following atropine administration suggests the drug is effectively counteracting OP-induced AChE inhibition.