COMPLICATIONS OF ANAESTHESIA IN OPTHALMIC SURGERY

PRESENTED BY :- DEVDUTTA NAYAK

Introduction

Anaesthetic requirements for ophthalmic surgery :

- Nature of the surgery - Surgeon’s preference - Patient’s preference Local

Topical Regional

General

Local anaesthesia for eyes

Non-akinetic and akinetic methods

Non –akinetic techniques

Topical ( drops & gel )

Subconjunctival

Topical anaesthesia for eyes Non-invasive

Minimal complications

Challenging operating conditions – no akinesia Popular for phaco-emulsification cataract surgery

Careful patient selection Co-operative Must be able to lie supine & still Sedation may be required

Usually, little or no sedation is necessary.

If necessary, a small dose of midazolam (0.01 mg/kg IV) is generally sufficient.

Oversedation, especially in the elderly, can lead to hypoventilation, hypoxia, and disorientation.

Usual agents: Proxymetacaine/Proparacaine 0.5% drops

Lignocaine 4% drops & 2% gel

Lignocaine 2% subconj. injection

2 – 3 drops instilled every 5 mins, 30 mins prior to surgery; action remains for 30 mins.

Akinetic techniques Akinetic blocks :

1. Needle techniques - Intraconal - Extraconal - Combined intraconal & extraconal 2. Cannula techniques - Sub- tenon’s block

Ophthalmic surgeons prefer immobile eyes Friedman et al - patients also prefer akinetic

regional ophthalmic block. Br J Ophthalmol 2004;88:333-5

Regional anaesthesia Advantages

Day cases Good akinesia & anaesthesia Minimal effect on IOP Minimal equipment required Low failure rate & high safety profile

Disadvantages Not suitable for all patients Complications Skill of anaesthetist Unsuitable for certain types of surgery

Anatomy

The orbit irregular four-sided pyramid Apex - pointing posteromedially & Base - facing anteriorly Annulus of Zinn → fibrous ring arising from the superior orbital fissure, forms the apex The surface of cornea, conjunctiva & lids → forms the base

Globe movements are controlled by - - Rectus muscles (inferior, lateral, medial &superior) - Oblique muscles (superior & inferior) Rectus muscles → origin - annulus of Zinn insertion - anterior to the equator of the globe,

Forms an incomplete cone

Orbit

Cone formed by rectus muscles

Nerve supply

Within the muscle cone :- - Optic nerve (II) - Oculomotor nerves (III) - Abducent nerve (VI nerve), - Nasociliary nerve (a branch of V nerve), - Ciliary ganglion and vessels

ALL3 SO4 LR6

Trochlear nerve runs outside & above annulus→ superior oblique (retained activity of this muscle is frequently observed ). Nasociliary nerve → Corneal & perilimbal conjunctival

Frontal & infraorbital nerves → remainder of the peripheral conjunctival

Cont.

Tenon’s space anatomy

Tenon’s capsule → thin membrane enveloping the globe & separating it from orbital fat

Inner surface separated from the outer surface of the sclera by a potential space the sub- tenon’s space

Sub- tenon’s space → lymphatic space

Follows the optic nerve & continues with subarachnoid space

Assessment and Preparation British Ophthalmic Anesthesia Society :- fasting regimen

there is difference in clinical practice by different anaesthesist Majority do not consider that it is necessary for the pt to be fasted

prior to local anesthesia for eye surgery ( 65 % did not restrict any food or liquid intake )

Complication rates of starvation or aspiration in ophthalmic regional anesthesia are unknown

Pre-op investigations Routine investigation of patients for catract surgery is not essential

Tests can be done to improve the general health of the patient if required.

Royal College of Anaesthetists and The Royal College of Ophthalmologists, 2001

Cont. Enquiry about bleeding disorders & related drugs

Konstantatos et al – Patients on anticoagulants to continue their medication. Clotting results should be within therapeutic range. Anaesth Intensive Care 2001;29:11-8

Recommendation for patients receiving antiplatelet agents - Currently no recomendation Katz J et al Study - Ophthalmology 2003; 110: 1784-8

- Procedures under topical, subconjunctival, sub- Tenon’s blocks are recommended Konstantatos A et al - Anaesth Intensive Care 2001;29:11-8

Chassot et al :- Extra occular & anterior chamber surgery can be conducted

during dual antiplatelet theraphy

Posterior chamber procedures require cessation of

clopidogrel ( but not asprine )

Only emergency surgery should be performed on full antiplatelet therapy

The risk/benefit ratio : preoperative withdrawal of antiplatelet drugs in order to perform regional block is not justified.

BJA 99 (3):316-28 (2007)

Cont. Anaesthetic & surgical procedures are explained All monitoring and anaesthetic equipments should be functional

Intravenous line :-

# Anaesthetists and The Royal College of Ophthalmologists, 2001 - IV line must be inserted before embarking on a needle block # Kumar CM, Dodds et al - - Presence of a secure IV line remains good clinical practice Ophthalmic Anaesthesia. The Netherlands, 2002.

Types of regional anaesthesia Akinetic Needle Technique

Peribulbar block (Pericone) Retrobulbar block (Intracone, Atkinson’s)

Sub- Tenon’s block

(parabulbar block, pinpoint anaesthesia,

medial episcleral block)

Retrobulbar block –

The Atkinson’s or classical retrobulbar block –

- Needle inserted through the skin, at the junction of

medial 2/3rd & lateral 1/3rd of the lower orbital margin

- 2 to 3 mL of local anaesthetic is injected deep into the

orbit behind the globe with the patient looking upwards

& inwards

- A separate 7th nerve block is required.

Complications of Facial Block • subcutaneous hemorrhage

• vocal cord paralysis

• laryngospasm

• dysphagia

• respiratory distress

Cont.

In modern retrobulbar block

- 25-G, 31-mm long needle is inserted through the

conjunctiva or skin in the inferotemporal quadrant as

far laterally as possible below the LR muscle.

- initial direction is tangential to the globe,

once past the equator ,needle goes upwards &

inwards to enter the space behind the globe

4 to 5 mL of local anaesthetic injected

Cont.

Peribulbar block : 2 injections Inferotemporal injection

Injection is made outside the cone. A 25-G, 31-mm long needle inserted through the

conjunctiva as far laterally as possible in the inferotemporal quadrant.

Once the needle is under the globe, it is directed along the orbital floor.

5 mL of local anaesthetic agent is injected.

Cont.

Cont.

Nasal injection A medial peribulbar block is performed to

supplement inferotemporal retrobulbar or peribulbar injection, particularly when akinesia is not adequate.

Rubin A. Eye blocks. In: Principles and Practice of Regional Anaesthesia :

Churhill Livingstone, 2003

25 or 27-G needle is inserted just below the supraornital notch to a depth of 15 to 20 mm

. 3 to 5 mL of local anaesthetic agent is injected

Cont.

Needle Selection for Akinetic Block Historically → 38 mm long needle

Chandra M Kumar et al – Distance between inferior orbital rim & apex 42 to 54 mm Ciliary ganglion lie → 7 mm in front of the apex ( as per study in 120 cadaveric skull ) Hence ciliary ganglion is 35 mm from the inferior orbital rim Patients with shallow orbit are at a ↑ risk with needles ≥ 35 mm

Vanden Berg et al –

Shorter (25 mm) needles are recommended

Some authors claim excellent results with 16-mm needles Anaesthesia 2004;59:775-80

Complication of agent

Systemic complication

- Over dose - Intravascular injection - Allergic or vasovagal reaction. - Into CSF within a cuff of dura around the optic nerve (confusion, convulsion, unconsiousness, respiratory & cardiac arrest)

- Over dose or intra vascular injection of adrenalin - Allergic reaction to hyaluronidase

Complications of the techniques Subconjuctival oedema (chemosis )

Frequently follow large volume of peribulbar injection than retrobulbar injection

Resolves with use of pressure No intra or postoperative problem

Bruising (ecchymosis ) Disfiguring Conjuctival rather than skin injection to prevent

bruising

Retrobulbar hemorrhage

Retrobulbar hemorrhage Incidence = 0.1 -1.7 % Predisposing factor : Elderly Vascular or haematological disease Pt on steroids, aspirin, NSAIDS, anticoagulant Manifest by : Tight eyelids, Proptosis Subconjuctival or periorbital hemorrhage & Dramatic increase in IOP Central retinal artery pulsation should be monitored. CRAO

reported. Impending retinal artery occlusion → Decompressive surgery (Lat.

Canthotomy & Cantholysis) Anterior chamber paracentesis IV Mannitol Postpone surgery if unmanageable.

Globe perforation

Both in peribulbar & retrobulbar blocks

Incidence :- 1 in 874 Gillow et al, Eye 1996;10:533-536

1 in 12,000 Devis et al, J Catract Refract surg;1994:20

1 in 16,224 Manner et al, Eye 1996;10:367-370

More in long & thin eye

Globes longer than 26mm are at risk

Pt who had or presenting for retinal detachment surgery and pt with myopia have long globes

Hamilton RC et al – Risk factors that predispose globe penetration - Presence of a long eye - Staphyloma or enophthalmos - Faulty technique - Lack of appreciation of risk factors - Uncooperative patient - Use of unnecessarily long needles OphthalmolClin North Am 1998;11:99-114.

Patients with axial myopia have greater risk of globe puncture

Risk rate is- 1 in 140 needle blocks with an axial length > 26 mm. Duker et al: Ophthalmology 1991;98:519-26. If axial length not known → power of patients spectacles

In high myopia & in case of pre-existing scleral buckle a classical peribulbar block or a single medial peribulbar injection is advocated.

Johnson, International Practice of Anaesthesia. 1996 & Vohra SB ,Br J Anaesth 2000;85:242-5.

Cont. Diagnosis by- Pain at time of injection Sudden loss of vision Hypotonia Poor red reflex or vitrous haemorage

When suspected or diagnosed →discuss with the surgeon May be avoided by : - Knowledge of orbital anatomy and length of globe - Initial tangential niddle insertion - Not going “up and in “ till niddle tip past the equator - Aiming for inferior portion of superior orbital fissure rather than orbital apex

Optic nerve atrophy- Direct injury to optic nerve or retinal artery Injection into optic nerve sheath or hemorrhage in optic nerve

sheath Retrobulbar hemorrhage

May lead to partial or complete visual loss

Amaurosis Mainly with retrobulbar block due to optic nerve block Not with peribulbar block Pt should be explained

Occulo cardiac reflex Occasionally Pt should be monitored

Penetration of optic nerve sheath(Brainstem Anaesthesia) Injection into the dural cuff of optic nerve subarachnoid spread of anaesthetic agent

Nicoll et al :- In 6000 retrobulbar block , incidence is 1 in 375 with 1 in 700 life threatening Anesthesia and analgesia;1987:66

Hamilton et al - incidence is 3 per 1000 Canadian journal of anaesthesia;1988: 35

All injection should be made with the globe in primary gaze position

Symptoms usually appear within 8 min ( immediately or upto 40 min after block)

Sign & symptoms :- Drowsiness , vomiting Convulsions Respiratory depression or arrest Neurological deficit Cardiac arrest Myotoxicity - Most frequently affect the inferior rectus muscle

- Usually recover but sometimes requires corrective surgery. - Rainin etal Highest concentration of local anesthetic should not be

used as they are found to be myotoxic. Archives of Opthalmology 1985;103

Direct injection into the muscle should be avoided.

OCR (Oculo-Cardiac Reflex)

a trigeminal-vagal reflex response that is manifested as cardiac arrhythmias and hypotension and may be elicited by pain,

pressure, or manipulation of the eyeball

afferent pathway:long and short ciliary nerves ciliary ganglion gasserian ganglion along the ophthalmic division of the trigeminal nerve (the fifth cranial nerve)main trigeminal sensory nucleus in

the floor of the fourth ventricle.

efferent pathway: starts in the vagal cardiac depressor nerve negative inotropic

and conduction effects

OCROccurs:

most often during strabismus surgery in children occasionally during retinal surgery & because of

retrobulbar block during nonophthalmic surgery if pressure is placed on

the eyeball.

The more acute the onset and the stronger and more sustained the traction, the more likely OCR is to occur

Hypoventilation and increased arterial carbon dioxide partial pressure significantly increase the incidence of bradycardia during strabismus surgery

OCRTo reduce the incidence and severity of OCR:

Intramuscular (?) administration of atropine gentle manipulation of the extraocular muscles control of ventilation to maintain normocapnia surgeon and anesthesiologist communication

treating OCR: The first step in is to stop stimulation by the surgeon before

the arrhythmia progresses to sinus arrest atropine (0.007 mg/kg IV) local injection of lidocaine near the eye muscle ensure that the depth of general anesthesia is adequate, the

patient is normocapnic, and surgical manipulation is gentle.

Sub Tenon’s Anaesthesia

Original idea of Turnbull (1884 )

Modified & popularised by Mein and Woodcock, Hansen, Stevens, Greenbaum & others

Also known as : Parabulbar block

Pinpoint anesthesia

Episcleral block

Anatomy of sub- tenon’s space

Sub- Tenon’s block Standard technique

Obtaining surface anaesthesia

Access to the sub-Tenon’s space

Insertion of a cannula

Administration of local anaesthetic agent

Inferonasal quadrant is the most common site of access (can be accessed from all 4 quadrants )

Stevens JD et al - Inferonasal quadrant allows good fluid distribution superiorly while avoiding area of surgery & damage to the vortex veins Br J Ophthalmol 1992; 76: 670–674

With the patient - looking upwards & outwards

Conjunctiva & Tenon’s capsule are gripped with non-toothed forceps (Moorfield forceps) ,5 to 10 mm away from the limbus

A small incision is made with scissors ( Westcott scissors) to expose the sclera & the cannula is inserted following the globe

Cont.

Cannulae for Sub-Tenon’s Block Metal or plastic

Commonly used cannula is → metal, 19-G, 2.54-cm long & curved with a blunt end

Others Southampton cannula Mid sub- Tenon cannula Anterior cannula Ultrashort cannula

Volume of LA varies from 1.5 -11 mL ( 3 to 5 mL is commonly used) Smaller volumes →provide globe anesthesia Larger volumes → if akinesia is desirable

One inch curved metal posterior sub-Tenon’s cannula

Plastic anterior sub-Tenon’s cannula.

Plastic mid-sub-Tenon’s cannula

Cont. Behndig A et al – Prolonged anesthesia & analgesia are obtained by inserting a catheter in the sub-Tenon’s space. J Cataract Refract Surg 1998;24:1307-9

Sub-Tenon’s block used primarily for cataract surgery Also effective for →Vitreoretinal surgery Panretinal photocoagulation Trabeculectomy Strabismus surgery Delivery of drugs

Sub-Tenon’s block favoured→ in patients on anticoagulants, aspirin & NSAIDs

Konstantatos A et al - Anaesth Intensive Care 2001;29:11-8

Passage of local anaesthetic agent during sub-Tenon’s injection Ultrasound & MRI studies shows –

injected anesthetic agent opens the sub-Tenon’s

space giving a characteristic ‘T-sign’

Local anaesthetic agent diffuses into intraconal & extraconal areas resulting in anesthesia & akinesia of the globe & eyelids

Intense analgesia is produced by blockade of the short ciliary nerves as they pass through the Tenon capsule

characteristic ‘T-sign’.

Complications of Sub-Tenon’s Block Minor complications → pain during injection, chemosis,

conjunctival hemorrhage & leakage of local anaesthetic Major complications → orbital & retrobulbar hemorrhage,

rectus muscle paresis & trauma, globe perforation, central spread of local anesthetic, orbital cellulitis etc.

Most of these complications occurs following use of 2.54- cm metal cannula.

Kumar CM et al - Eur J Anaesthesiol 2005;22:567-77.

Smaller or flexible cannulae appear to be safer but the incidence of minor complications increases.

Kumar CM & Dodds C et al - An Br J Anaesth 2001;87:631.

Pain during injection Multifactorial Incidence with posterior metal cannula ≈ up to 44%

Pain scores on a VAS have been reported as high as 5 Stevens JD - Br J Ophthalmol 1992; 76: 670–674

Smaller cannulae appear to offer a marginal benefit Kumar CM, & Dodds et al - Eye 2004; 18: 873–876 Guise PA et al -

Premedication or sedation during sub-Tenon’s injection does not add any benefit Anesthesiology 2003; 98: 964–968

Preoperative → explanation of the procedure, good surface anesthesia, gentle technique, slow injection of warm local anaesthetic agent & reassurance are considered good practice

Pharmacological Considerations during Ophthalmic Regional Block Local Anaesthetic Agent All the modern LA are suitable & studies have shown little difference in the quality of anesthesia, analgesia & akinesia Adjuvant Vasoconstrictors :- - Increases the intensity and duration of block & minimize bleeding from small vessels pH Alteration :- - Alkalization decreases onset time and prolong the duration of effect after needle block . Zahl K et al - Anesthesiology 1990;72:230

- No such benefit is seen during sub-Tenon’s block. Moharib et al - Reg Anesth Pain Med 2000;25:514-7

Hyaluronidase :-

Improves the effectiveness & quality of needle & sub- Tenon’s block

use remains controversial The amount of hyaluronidase used - 5 to150 IU / mL Orbital swelling - allergic actions or excessive doses & orbital

pseudotumour have been reported

Others :-

Muscle relaxants & clonidine are known to increase the onset & potency of orbital block

use is neither routine nor recommended.

Sedation and Ophthalmic Regional Blocks commonly used during topical anesthesia

patients, in whom explanation & reassurance have no benefit

opioids & small doses of IV anesthetic induction agents are used

The Royal College of Anesthetists and The Royal College of Ophthalmologists, 2001 The routine use of sedation is discouraged A means of providing supplemental O2 should be available Sedation should only be used to allay anxiety & not to cover

inadequate block

Intraocular Pressure (IOP) and Ophthalmic Regional Blocks Changes in IOP after retrobulbar & peribulbar injections

are controversial

IOP is generally reported to increase immediately after injection

Bowman R et al - Br J Ophthalmol 1996;80:394-7. Palay DA et al - Ophthalmic Surg 1990;21:503-7. Watkins R et al - Br J Ophthalmol 2001;85:796-8.

IOP is not seen to increase after sub-Tenon’s block Ling R etal - J Cataract Refract Surg 2002;28:113-7. Vallance etal - J Cataract Refract Surg 2004;30:433-6. Alwitry etal - Eye 2001;15:733-5.

Retained Visual Sensations During Ophthalmic Regional Blocks Many patients experience intraoperative visual sensations

This include light, colours, movements & instruments during

all forms of local ophthalmic anesthesia

During sub- Tenon’s block (16%) found the experience to be unpleasant or frightening

Wickremasinghe et al - Eye 2003; 17: 501–-505

Patients receiving orbital blocks should receive preoperative

advice as this may alleviate an unpleasant experience

Intraoperative Care and Monitoring Patient should be comfortable with soft padding over

pressure areas

The Royal College of Anaesthetists and The Royal College of

Ophthalmologists

All patients undergoing major eye surgery under local anesthesia should be monitored with pO2 ECG Maintenance of verbal contact

Choice of Technique Preference for anaesthetic technique by surgeons & patients varies

Friedman et al - 72% patients preferred block anesthesia to topical anesthesia Br J Ophthalmol 2004;88:333-5.

Ruschen et al supports this view - Patients have higher satisfaction scores with sub- Tenon’s block over topical anesthesia alone. Br J Ophthalmol 2005;89:291-3

The choice of technique depend on a balance between - patient’s wishes - operative needs of the surgeon - skills of the anesthetist & - place where such surgery is being performed

The Rules

2001 Guidelines (RCA & Coll. of

Ophthalmologists) Trained staff Surgeons – topical /sub- conjunctival / sub- Tenon

( without anaesthetist ) Anaesthetist & iv access with retrobulbar &

peribulbar blocks Anaesthetist in charge when sedation is used

General anaesthesia for ophthalmic surgery

Indications: Patient refusal Children / learning difficulties / movement

disorders Major / lengthy procedures Inability to lie still / flat Penetrating Eye Injuries

Specific Complications:

IOP rise : ? Ketamine

Succynil choline

Intraocular Gas Expansion : N2O

The effect of anesthetic agents on intraocular pressure (lOP).

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GENERAL ANESTHESIA

Respiratory complications Laryngoscope & intubation Respiratory obstruction & spasm (isoflurane) Hypoxemia (N2O) Hypercapnia / Hypocapnia Hypoventilation Aspiration pneumonia Chest infections

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Cardiovascular complications Hypertension Hypotension Cardiac arrhythmias Death (halothane)

Neurological complications Headache Delayed recovery Perioperative neuropathy Hallucinations & unpleasant dreams (ketamine)

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Postoperative nausea & vomiting (propofol, etomidate)

Temperature changes Hypothermia Hyperthermia (atropine, halothane)

Allergic drug reactions Itching Anaphylaxis

Hypotension, arrhythmia, tachycardia Bronchospasm, cough, dyspnea

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Complications of positioning Air embolism Nerve palsies

Brachial plexus, Radial nerve, Ulnar nerve Skin necrosis

Miscellaneous Renal dysfunction (enflurane) Muscle pain (succinylcholine)

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