Question

Which of the following intravenous anaesthetic agents is safe even if accidentally injected intra-arterially?

• A. Thiopentone
• B. Propofol
• C. Midazolam
• D. Methohexitone

Hint:

Barbiturates and benzodiazepines damage arteries; the lipid-emulsion induction agent does not.

Answer 1

The Correct Option is B

Step 1: Inadvertent intra-arterial injection of certain IV drugs causes intense vasospasm, crystal deposition, thrombosis and distal ischaemia, which can lead to gangrene of the limb. The risk depends on the specific agent.

Step 2: Barbiturates such as thiopentone and methohexitone are highly alkaline and precipitate as crystals in arterial blood, producing severe vascular injury. Benzodiazepines such as midazolam and diazepam are also associated with serious complications after intra-arterial injection.

Step 3: Propofol, in contrast, does not cause vascular injury or adverse reactions on accidental extravasation or intra-arterial injection. Etomidate is similarly considered safe. This makes propofol the correct answer.

Step 4: Hence thiopentone, midazolam and methohexitone are all unsafe intra-arterially, whereas propofol is safe.