**Question:** All true about accidental intra-aerial injection of Thiopentone except:-

A. It causes immediate respiratory distress and hypoxia
B. It induces unconsciousness
C. It results in severe hypertension
D. It leads to immediate cardiac arrest

**Core Concept:**
Thiopentone is a barbiturate anesthetic drug used for rapid induction of general anesthesia. When administered intra-aerially, it can lead to immediate respiratory distress and hypoxia due to its effect on the respiratory center in the brainstem. However, the drug does not cause severe hypertension, cardiac arrest, or anesthesia.

**Why the Correct Answer is Right:**
Option A is correct because Thiopentone, when administered intra-aerially, causes respiratory depression and hypoxia due to its effect on the respiratory center. This immediate respiratory distress is a direct consequence of the drug's action on the central respiratory center.

Option B is incorrect because Thiopentone is a sedative-hypnotic drug used for anesthesia induction, not for inducing unconsciousness.

Option C is incorrect because Thiopentone is known for its sedative and hypnotic properties, not for causing hypertension. It depresses the central nervous system, leading to sedation and loss of consciousness, but does not cause significant hypertension.

Option D is incorrect because Thiopentone does not cause cardiac arrest upon intra-aerial administration. While it may lead to hypotension due to vasodilation, cardiac arrest is not a direct consequence of Thiopentone administration.

**Why Each Wrong Option is Incorrect:**
Option B (induction of unconsciousness) is incorrect because the drug is designed for anesthetic purposes, not for causing unconsciousness. It primarily causes sedation and loss of consciousness, not unconsciousness itself.

Option C (hypertension) is incorrect because Thiopentone causes vasodilation, which can lead to hypotension, but it does not directly cause hypertension.

Option D (cardiac arrest) is incorrect because Thiopentone's primary effect is sedation and loss of consciousness. Cardiac arrest is not a direct consequence of Thiopentone administration but can result from hypotension due to vasodilation.

**Clinical Pearl:**
In summary, accidental intra-aerial administration of Thiopentone can cause respiratory depression, hypotension, and sedation, but it does not result in severe hypertension, cardiac arrest, or induction of unconsciousness. The drug primarily affects the central nervous system leading to sedation and loss of consciousness, and hypotension due to vasodilation is a secondary effect.