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Anaesthesia for eye and ear-nose-throat surgery
In the eye, intraocular pressure is protected, the oculocardiac reflex is recognised and N2O is avoided when there is a gas bubble; in the throat, the airway is shared with the surgeon, and bleeding after tonsillectomy is treated as a full stomach with hypovolaemia.
Why it matters in the exam
The exam asks about the oculocardiac reflex (traction on the eye muscles, bradycardia and asystole, treatment), what raises and lowers intraocular pressure, an open globe with a full stomach, a gas bubble in the eye and the ban on N2O, the complications of a retrobulbar block, and eye drops with systemic effects. On the ENT side it asks about bleeding after tonsillectomy, a foreign body in a child's airway, and facial nerve monitoring in ear surgery.
The oculocardiac reflex runs through the first division of the trigeminal nerve and the vagus; it is common in strabismus surgery in children. The traction is stopped, and if bradycardia persists — atropine or glycopyrrolate; the reflex fatigues with repeated stimulation. Normal intraocular pressure is 10–20 mmHg; coughing, laryngoscopy, high CO2 and succinylcholine raise it, and most anaesthetic drugs lower it. After injection of SF6 or C3F8 gas into the eye, N2O may enlarge the bubble and harm vision — it is forbidden for weeks.
A retrobulbar block may cause bleeding behind the eye, globe perforation, an oculocardiac reflex, and spread to the brainstem with apnoea — so the patient is observed after the block. With echothiophate (cholinesterase-inhibiting drops) the action of succinylcholine is prolonged. In bleeding after tonsillectomy the child has swallowed blood, is hypovolaemic and often frightened: volume is restored, two suction devices and a smaller tube are prepared, and an RSI is done. With a foreign body in the airway spontaneous breathing is kept until the rigid bronchoscope is in place. In ear surgery with facial nerve monitoring paralysis is avoided.
Key points
- Oculocardiac reflex: stop the traction, then atropine.
- Intraocular pressure rises with coughing, laryngoscopy, CO2 and succinylcholine.
- Gas bubble in the eye — no N2O.
- Retrobulbar block — bleeding, perforation, apnoea from brainstem spread.
- Bleeding after tonsillectomy — volume and RSI.
Summary table
| Situation | What is done | Exam point |
|---|---|---|
| Oculocardiac reflex | Stop traction; atropine or glycopyrrolate | First division of the trigeminal and the vagus; strabismus in children |
| Open globe and full stomach | RSI, usually high-dose rocuronium; avoid coughing and pressure on the eye | Succinylcholine transiently raises intraocular pressure |
| Gas bubble in the eye (SF6, C3F8) | No N2O for weeks | The bubble expands and vision is harmed |
| Retrobulbar block | Observation after the block | Bleeding, perforation, spread to the brainstem |
| Bleeding after tonsillectomy | Volume, two suction devices, smaller tube, RSI | A stomach full of blood |
A free exam question
?מה מאפיין את שרירי גלגל העין (the question as examined, in Hebrew)
- א. הם שרירים חלשים במיוחד שמאפשרים תנועה עדינה ומדויקת
- ב. כל סיב שריר מעוצבב על ידי מספר תאי עצב ולא אחד
- ג. הם שרירים מהירים מאד שמאפשרים מעקב אחר עצמים נעים
- ד. Succinylcholine אינו משפיע עליהם
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Sources
- Miller's Anesthesia, 9th edition (2020) — Ophthalmic Surgery; Anesthesia for Otolaryngologic and Head-Neck Surgery
- Morgan & Mikhail's Clinical Anesthesiology, 7th edition (2022) — Anesthesia for Ophthalmic Surgery; Anesthesia for Otorhinolaryngological Surgery
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.