Question

During squint surgery, the anaesthesiologist notices on the monitor that the blood pressure (and heart rate) suddenly drops to a dangerously low level. What is the best immediate management?

• A. Give atropine
• B. Increase the level of anaesthesia
• C. Ask the surgeon to stop the surgery
• D. Give adrenaline

Hint:

Vagal bradycardia from eye-muscle traction needs an antimuscarinic.

Answer 1

The Correct Option is A

Step 1: Recognise the reflex. A sudden fall in heart rate and blood pressure during squint (extraocular muscle) surgery is the oculocardiac reflex, triggered by traction on the extraocular muscles or pressure on the globe. The afferent limb is the trigeminal nerve and the efferent limb is the vagus nerve.

Step 2: First step in management. The immediate action is to ask the surgeon to release the traction, which usually aborts the reflex.

Step 3: Drug of choice. If bradycardia persists, the specific treatment is intravenous atropine, an antimuscarinic that blocks the vagal slowing of the heart and restores rate and pressure.

Step 4: Why the printed key is corrected. The printed answer of adrenaline is medically wrong. The classic, definitive drug for the vagally mediated oculocardiac reflex is atropine, not adrenaline. Merely deepening anaesthesia does not treat the reflex.