Intra-arterial injection of thiopental should be avoided due to risk of what?

• A. Safe with no risk
• B. AVOID! Can cause intense vasoconstriction and tissue necrosis; treat with phentolamine and sympathectomy
• C. Causes mild local irritation only
• D. Benefits by increasing cerebral perfusion

Answer: (B)

The risk comes from severe vasospasm and resulting tissue ischemia if thiopental is injected into an artery. Thiopental can irritate the arterial endothelium and cause intense arterial vasoconstriction, which may progress to tissue necrosis in the supplied region. Because of this, intra-arterial administration should be avoided.

If accidental intra-arterial exposure occurs, the preferred management is prompt reversal of the vasospasm with an alpha-adrenergic blocker such as phentolamine, which dilates the vessels and reduces ischemic injury. In especially resistant cases, more aggressive measures like sympathectomy may be considered to relieve persistent vasospasm. This explains why the correct choice highlights intense vasoconstriction and tissue necrosis and the treatment approach.