Intra arterial injection of thiopentone causes –

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.