This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anaesthesia
Intra arterial injection of thiopentone causes – 
Select and explain. 
A. Vasospasm, B. Vasodialation, C. Necrosis of vessel wall, D. Hypotension
A: Vasospasm
Answer: A: Vasospasm 
Explanation: Inadverent intra-arterial injection causes local vasoconstriction (vasospasm) and thrombosis which can cause ischemia and gangrene of the limb.
Note-IV injection cause generalized venodilatation due to which there is pooling of blood & hypotension. On the other hand intra-arterial injection results in localized vasospasm of the involved artery.