anesthesia for ophthalmic sx edit

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OculoplasticSquintCorneaLensGlaucomaVitreoretinalNeuro-

ophthalmology

Local anesthesia Topical anesthesia Regional anesthesia

General anesthesiaOphthalmic surgery

Local Local anesthesiaanesthesia

Local Local anesthesiaanesthesia

General General anesthesiaanesthesia

VSVS

Many benefits Physiological disturbance PONV Economic

Topical / Regional anesthesia

Non-invasiveVirtually no complications

Challenging operating conditions – no akinesia

Increasingly popular for phacoemulsification cataract surgery

Careful patient selection Co-operative Not distressed Straightforward surgery Must be able to lie supine and still Not claustrophobic

Sedation (Anesthesiologist stand-by)

IV access / supplementary O2

Which LA? Proxymetacaine / amethocaine Preservative free preferred ± topical NSAID and mydriatic

20-30 min before surgeryTwo to three drops every 5 minutes

Cornea is avascular – once absorbed LA remains for about 30 min

Supplemented by incremental injection

What about this choice?

Advantages Day cases Good akinesia and Anesthesia Minimal effect on IOP Minimal equipment required

Disadvantages Not suitable for all patients Complications Skill of Surgeons/Anesthesiologists Unsuitable for certain types of surgery

Orbit – shape of irregular pyramid Base at front Axis points

posterio-medially towards skull

Globe lies in anterior part of orbit

- sits high and lateral

Four rectus muscles arise from the back of orbit

Insert into the globe just forward of equator

Form a cone - boundary

between two

compartmentsCENTRAL(retrobulbar)

PERIPHERAL(peribulbar)

Within the cone Optic nerve Opthalmic artery & vein Ciliary ganglion Oculomotor nerves

Sensory supply to orbit from opthalmic division Trigeminal nerve enters the orbit through superior orbital

fissure

Peribulbar block (Pericone)Retrobulbar block (Intracone)

Sub-Tenon’s block

Comfort Assistant providing

reassurance O2 saturation,

ECG, BP monitoring

Right angled screen providing O2

Intravascular injectionAnaphylaxisHemorrhageSubconjunctival edemaPenetration / perforation of the globeCentral spread (sub-arachnoid)Optic nerve atrophy

2001 Guidelines (RCA & College Of Ophthalmologists) Trained staff Surgeons – topical / sub-conjunctival /

sub-Tenon – without Anesthesiologist Anesthesiologist & iv access when

retrobulbar / peribulbar Anesthesiologist in charge when

sedation used

Indications: Patient refusal Children / learning difficulties /

movement disorders Major / lengthy procedures Inability to lie still / flat Claustrophobic

Patients at extreme age Old – medication, confused, deaf, blind,

with co-morbid like DM, CAD, HTN, COPD Young – congenital anomalies, temp. &

fluid balance

Opthalmic drugs Timolol – B-Blocker Phospholine iodide – anti-cholinesterase

Normally 10-20 mmHg

Must be controlled when operating within the globe

IOP impaired op. conditions expulsion of intra-ocular contents

Mild IOP improved op. conditions

Increasing External pressure e.g.

face mask Venous pressure Arterial pressure Hypoxia Hypercarbia Succinylcholine,

Ketamine Laryngoscopy Coughing

Decreasing Venous pressure Arterial pressure Hypocarbia IV induction agents NDMRD Aqeous volume

(acetazolamide) Vitreous volume

(mannitol)

Careful with face mask No ketamine Laryngoscopy after completely

paralyzed 4% Xylocaine topical anesthesia at

vocal cord Head up tilt

Monitoring: ECG, oximeter, capnograph and peripheral nerve stimulator if available

Continue volatile agent until spontaneous respiration is resumed after reversal

Anti-emetic may be administered No food/drink for 3 hours to reduce the

possibility of aspiration of gastric contents

★ If no muscle relaxants and patient breathes spontaneously, the depth of anesthesia must be increased to prevent coughing or straining against the tube.

Avoid nitrous in vitreoretinal surgery Bubbles of sulphurhexafluoride (SF3)

Emergence without coughing Deep extubation Lignocaine on cords Bolus lignocaine/ propofol beforehand

Scoline or not??

Traction on EOM may cause sudden and profound bradycardia via oculocardiac reflex mediated by CN X

Occasionally seen during other forms of eye surgery e.g. retinal detachment

Prevention Moderated by LA (abolish afferent arc) Avoid hypoxia/hypercapnia (sensitizes the

reflex) Prophylactic anticholinergic ★esp in children

Management STOP stimuli at once Ensure adequate ventilation Ensure sufficient anesthetic depth If needed, atropine 0.02 mg/kg IV

Is atropine useful?Is atropine useful? Controversial 0.4 mg IM as a premedicant has no

vagolytic effect after 60 min and is of no value in preventing or treating OCR

0.4 mg IV is effective for 30 minutes in preventing bradycardia associated with the OCR

Doses >0.5 mg IV can cause tachycardia★

Examination in children can often be provided satisfactorily via a face mask

If the naso-lacrimal duct is to be irrigated Intubation or Positioning the patient with a pillow

under the shoulders

KetamineKetamine can also be used but pre-medication with atropineatropine is essential to prevent laryngospasm caused by excessive secretions.

If sedation is required Midazolam (0.5 -1 mg) with Fentanyl 25 – 50 mg or Propofol 20 mg.

Peribulbar block is advisable when axial length is less than 26mm and patient can lie flat & still.

Haelan (Sodium Hyaluronate) is injected at the time of incision to maintain the shape of anterior chamber and controls the vitreous bulge.

Cataract Surgery can be performed under Regional Anesthesia without discontinuing anticoagulant therapy (Prothrombin Time 1.5 times control).