Transcript Eye surgery
Eye surgery Requirements for eye surgery: 1. 2. 3. 4. 5. 6. 7. Akinesia of the eye Intense analgesia Minimal bleeding (avoid HT or movement of eye) Management of oculo-cardiac reflex Control of intra-ocular pressure (IOP) Beware of drug interactions Smooth recovery with no PONV Oculo-cardiac reflex • Occurs with pulling of eye muscles/pressure on eye ball • Afferent = N V (V1), efferent = N X → bradycardia • Most common in children for strabismus repair, but can occur during any ophthalmic procedure • Management: 1. Ask surgeon to stop pulling on muscles 2. Confirm adequate depth of anaesthesia 3. Administer atropine (0.02 mg/kg) if bradycardia persists 4. The reflex eventually fatigues itself with repeated pulling and release of eye muscles Control of intra-ocular pressure • Eye cavity = hollow sphere with a rigid wall. If contents ↑→ IOP ↑→ extrusion of ocular contents through open surgical/trauma wound • Anaesthesia can → ↑ IOP due to 1. laryngoscopy/ intubation (HT), 2. airway obstruction, coughing, ↑ CVP, Trendelenburg position (↓ venous drainage) 3. ↑ PaCO2 (vasodilatation →↑ eye blood flow 4. Drugs: Ketamine, suxamethonium →↑ IOP • Other anaesthetic drugs (opioids, induction agents, muscle relaxants do not ↑ IOP and are thus save Drug interactions • Ecothiopate is a pseudocholinesterase (pCE) inhibitor used to ↓ IOP but it can prolong the action of suxamethonium (which is broken down by pCE) • Timolol is a β-blocker used in the eye to ↓ IOP but can cause bradycardia, asthma etc Strabismus surgery • Oculo-cardiac reflex = common • ↑ incidence of malignant hyperthermia (temperature monitoring = NB) • ↑ incidence of PONV (consider prophylactic anti-emetics) The open eye • Emergency, thus can not wait for pt to be NPO • Do rapid sequence induction (trauma delays gastric emptying) • Avoid Ketamine • Consider suxamethonium (although ↑ IOP), because it is given with IV induction agent and opioid which both decrease IOP. Suxamethonium provide excellent intubation conditions and thus prevents ↑ IOP due to coughing etc. • Avoid all factors that ↑ IOP (see above)