REGIONAL ANAESTHESIA IN OPTHALMIC SURGERY

1
(No Transcript)
2
REGIONAL ANAESTHESIA IN OPTHALMIC SURGERY

• MODERATOR - Dr. RANI SUNDAR
• PRESENTED BY -
• 
  UMAKANTH
• 
  BIKASH

www.anaesthesia.co.in anaesthesia.co.in_at_gmail.c
om
3
Introduction

• Anaesthetic requirements for ophthalmic surgery
  
• - Nature of the surgery
• - Surgeons preference
• - Patients preference
• Local
• Topical
• Regional
• General

4
Local anaesthesia for eyes

• Non-akinetic and akinetic methods
• Non akinetic techniques
• Topical ( drops gel )
• Subconjunctival
• Deep fornix anaesthesia

5
Akinetic techniques

• Akinetic blocks
• 1. Needle techniques
• - Intraconal
• - Extraconal
• - Combined intraconal
  extraconal
• 2. Cannula techniques
• - Sub- tenons block
• Ophthalmic surgeons prefer immobile
  eyes
• Friedman et al - patients also prefer akinetic
  regional ophthalmic block.
• 
  Br J Ophthalmol
  200488333-5

6
Topical anaesthesia for eyes

• Non-invasive
• Minimal complications
• Challenging operating conditions
• 
  no akinesia
• Popular for phacoemulsification cataract surgery
• Careful patient selection
• Co-operative
• Must be able to lie supine still
• Sedation

7
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

8
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

9
Orbit
10
Cone formed by rectus muscles
11
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

12
Cont.
13
Tenons space anatomy

• Tenons 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- tenons space
• Sub- tenons space ? lymphatic space
• Follows the optic nerve continues with
  subarachnoid space

14
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

15
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 20012911-8
• Recommendation for patients receiving
  antiplatelet agents
• - Currently no recomendation
• Katz J et al Study -
  Ophthalmology 2003 110 1784-8
• - Procedures under topical,
  subconjunctival, sub- Tenons
• blocks are recommended
• Konstantatos A et al -
  Anaesth Intensive Care 20012911-8

16

• 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 theraphy
• The risk/benefit ratio of preoperative withdrawal
  of antiplatelet drugs in order to perform
  regional blocked is not justified
• 
  BJA 99 (3)316-28 (2007)

17

• 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 19981199-114.
• Patients with axial myopia have greater risk of
  globe puncture
• Risk rate is- 1 in 140 needle blocks with an
  axial length gt 26 mm.
• 
  Duker et al Ophthalmology 199198519-26.
• If axial length not known ? power of patients
  spectacles
• In highmyopia 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 200085242-5.

18
Cont.

• Anaesthetic surgical procedures are explained
• All monitoring and anaesthetic equipments should
  be functional
• Intravenous line -
• Mathew et al - ? insertion of an IV
  line for topical
• or sub-
  Tenons injection
• 
  J Cataract Refract Surg
  2003291132-6.
• 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.

19
Types of regional anaesthesia

• Akinetic Needle Technique
• Peribulbar block (Pericone)
• Retrobulbar block (Intracone, Atkinsons)
• Sub- Tenons block
• (parabulbar block, pinpoint anaesthesia,
• medial episcleral block)

20
Retrobulbar block

• The Atkinsons 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.

21
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

22
Cont.
23
Cont.
Insertion point direction of needle for extreme
inferolateral intraconal injection
Final position of needle after intraconal needle
placement.
24
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.
• Many patients require a supplementary injection.

25
Cont.
26
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 in the blind pit
  between the caruncle medial canthus to a depth
  of 15 to 20 mm
• .
• 3 to 5 mL of local anaesthetic agent is injected

27
Cont.
28
Cont.
Direction and placement of needle for medial
peribulbar injection
29
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 200459775-80

30

• Bevel and tip of needle controversy
• Grizzard WS et al -
• Sharp narrow-gauge needles (25 to 31
  gauges) reduce
• Discomfort on insertion at the expense of a
  reduced tactile feedback
• Theoretically higher risk to recognise a globe
  perforation
• 
  
  Ophthalmology 1991981011-6
• Kimble JA et al
• Advantage of blunt needles
• Blood vessels were pushed rather than traumatised
  
• Tissue planes could be more accurately defined
• 
  Arch Ophthalmol
  1987105749
• Grizzard WS et al
• Blunt needles
• More likely to cause greater damage when misplace
• 
  Ophthalmology 1991981011-6

31
Complication of agent

• Systemic complication
• - Over dose
• - Intravascular
• - 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

32
Complications of the techniques

• Subconjuctival odema (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

33
Retrobulbar hemorrhage

• Incidence 0.1 -1.7
• Predisposing factor Elderly
• Vascular
  or haematological disease
• Pt on
  steroids, aspirin, NSAIDS, anticoagulant
• Manifest by Tight eyelids
• Subconjuctival or
  periorbital hemorrhage
• Dramatic increase in
  IOP
• Central retinal artery pulsation should be
  monitored
• Impending retinal artery occlusion ?
  Decompressive surgery or
• 
  Anterior chamber paracentesis
• Postpone surgery
• Cionni et al -
• If pressure reducing device decreases
  IOP, surgery can be
• carried out
  opthalmology 1991 98

34
Globe perforation

• Both in peribulbar retrobulbar blocks
• Incidence - 1 in 874 Gillow et al, Eye
  199610533-536
• 1 in 12,000 Devis et
  al, J Catract Refract surg199420
• 1 in 16,224 Manner
  et al, Eye 199610367-370
• 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

35
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

36

• 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

37
Penatration of optic nerve sheath

• 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 analgesia198766
• Hamilton et al - incidence is 3 per 1000
• 
  Canadian journal of anaesthesia1988 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)

38

• Sign symptoms - Drowsiness , vomiting
• 
  Contralateral blindness
• 
  Convulsion
• 
  Respiratory depression or arrest
• 
  Neurological deficit
• 
  Cardiac arrest
• Myotoxicity
• - Most frequently affect the inferior rectus
  muscle
• - Usually recover but sometimes required
  corrective surgery
• - Rainin etal
• Highest concentration of local
  anesthetic should not be
• used as they are found to be myotoxic
• 
  Archives of Opthalmology 1985103
• Direct injection into the muscle should be
  avoided

39
Sub Tenons 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

40
Anatomy of sub- tenons space
41
Sub- Tenons block

• Standard technique
• Obtaining surface anaesthesia
• Access to the sub-Tenons space
• Insertion of a cannula
• Administration of local anaesthetic agent

42

• 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 670674
• With the patient - looking upwards outwards
• Conjunctiva Tenons 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

43
Cont.
44
Cannulae for Sub-Tenons 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

45
One inch curved metal posterior sub-Tenons
cannula
46
Plastic anterior sub-Tenons cannula.
47
Plastic mid-sub-Tenons cannula
48
Cont.

• Behndig A et al
• Prolonged anesthesia analgesia
  are obtained
• by inserting a catheter in the
  sub-Tenons space.
• 
  J Cataract Refract Surg
  1998241307-9
• Sub-Tenons block used primarily for cataract
  surgery
• Also effective for ?Viteroretinal surgery
• Panretinal
  photocoagulation
• 
  Trabeculectomy
• Strabismus
  surgery
• Delivery of
  drugs
• Sub-Tenons block favoured? in patients on
  anticoagulants, aspirin NSAIDs
• Konstantatos
  A et al - Anaesth Intensive Care 20012911-8

49
Passage of local anaesthetic agent during
sub-Tenons injection

• Ultrasound MRI studies shows
• injected anesthetic agent opens the
  sub-Tenons
• 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

50
characteristics T-sign.
51
Complications of Sub-Tenons 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 cellulites etc
• Most of these complications occurs following use
  of 2.54- cm metal cannula.
• Kumar CM et al -
  Eur J Anaesthesiol 200522567-77.
• 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 200187631.

52
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 670674
• Smaller cannulae appear to offer a marginal
  benefit
• 
  Kumar CM, Dodds et al -
  Eye 2004 18 873876
• Guise PA et al -
• Premedication or sedation during
  sub-Tenons injection does not add any benefit
  Anesthesiology 2003 98 964968
• Preoperative ? explanation of the procedure, good
  surface anesthesia, gentle technique, slow
  injection of warm local anaesthetic agent
  reassurance are considered good practice

53

• Chemosis-
• Incidence 25 to 60 with a posterior cannula
• 100 with shorter
  cannulae
• Resolves with application of digital pressure
• Minor conjunctival hemorrhage
• Incidence 20 to 100 depends on the cannula
  used
• Loss of local anaesthetic volume during injection
• Anaesthesia and akinesia
• Akinesia is volume dependent
• (large proportion develop akinesia
  with 4-5 ml of LA )
• Superior oblique muscle lid movements may
  remain active in a significant number of patients
• \

54
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 199072230
• - No such benefit is seen during
  sub-Tenons block.
• Moharib et
  al - Reg Anesth Pain Med 200025514-7

55

• Hyaluronidase -
• Improves the effectiveness quality of needle
  sub- Tenons 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.

56
Sedation and Ophthalmic Regional Blocks

• commonly used during topical anesthesia
• patients, in whom explanation reassurance have
  no benefit
• Short acting BZP, opioids small doses of IV
  anesthetic induction agents are used
• The Royal College of Anaesthetists 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

57
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 199680394-7.
• 
  Palay DA et al - Ophthalmic Surg
  199021503-7.
• 
  Watkins R et al - Br J Ophthalmol
  200185796-8.
• IOP is not seen to increase after sub-Tenons
  block
• Ling R etal -
  J Cataract Refract Surg 200228113-7.
• Vallance
  etal - J Cataract Refract Surg 200430433-6.
• Alwitry
  etal - Eye 200115733-5.

58
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- Tenons 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

59
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
• Spo2
• ECG
• NIBP
• Maintenance of verbal contact

60
Choice of Technique

• Preference for anaesthetic technique by surgeons
  patients varies
• Recent article by Friedman et al -
• 72 patients preferred block anesthesia
  to topical anesthesia
• 
  Br J Ophthalmol 200488333-5.
• Ruschen et al supports this view -
• Patients have higher satisfaction scores
  with sub- Tenons block
• over topical anesthesia alone.
• 
  Br J Ophthalmol 200589291-3
• The choice of technique depend on a balance
  between
• - patients wishes
• - operative needs of
  the surgeon
• - skills of the
  anesthetist
• - place where such
  surgery is being performed

61
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

62
THANK YOU

www.anaesthesia.co.in anaesthesia.co.in_at_gmail.c
om