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You are in Home >> Exams >> Mitchell Anaesthetic Notes


Regional anaesthesia

Created: 23/10/2006
Updated: 10/1/2007
 

Lumbar and lumbosacral plexus

  • Lumbar plexus
    • Four roots: ventral rami of L1-4
      • L1 divides into superior and inferior branches
        • Superior: ilioinguinal and iliohypogastric nn.
        • Inferior: joins L2 to form genitofemoral n.
      • L2-3 give branches to form lateral femoral cutaneous n.
      • L2-4 give branches to form femoral and obturator nn.
  • Iliohypogastric nerve
    • Runs superior to iliac crest between internal oblique and transversus abdominis
    • Motor to abdominal wall
    • Sensory branches: lateral (hip) and anterior cutaneous (suprapubic)
  • Ilioinguinal nerve
    • Immediately inferior to iliohypogastric
    • Traverses inguinal canal
    • Cutaneous branches to upper inner thigh and root of penis or labia majora
  • Genitofemoral nerve
    • Genital branch traversus inguinal canal and supplies cremaster and lateral scrotal skin
    • Femoral branch arises medially and passes under inguinal ligament with external iliac a., passes through saphenous opening and supplies skin over femoral triangle
  • Lateral femoral cutaneous nerve
    • Passes under lateral part of inguinal ligament, deep to fascia lata
    • Supplies skin of lateral thigh from greater trochanter to above knee
  • Obturator nerve
    • Runs on the medial and posterior aspect of psoas, though the obturator canal
    • Supplies adductors, hip and knee joints and skin over medial thigh just above knee
  • Femoral nerve below
  • Lumbosacral plexus
    • Five roots: ventral rami of L4-S3
      • Collateral branches to gluteal region, pudendal plexus and hip joint
    • Anterior and posterior terminal branches
      • Form posterior cutaneous nerve of thigh
      • Anterior branches form tibial portion of sciatic nerve
      • Posteror branches form common peroneal portion of sciatic nerve

Psoas compartment block    

  • Anatomy
    • Lumbar nerve roots run in compartment posterior to psoas muscle
  • Needle placement
    • Patient in lateral position, knees to chest, sedation required
    • 15 cm needle inserted 5 cm lateral and 3 cm inferior to L4 spinous process
    • Strikes L5 transverse process
    • Redirected slightly superiorly and advanced until loss of resistance at 12±2 cm
  • Local anaesthetic
    • 20 ml air to dilate space
    • 30 ml of dilute solution
  • Indications
    • Analgesia or anaesthesia in region of femoral, obturator and lateral cutaneous n.

 Femoral nerve block, three-in-one block

  • Anatomy
    • Femoral nerve arises from L2-4 roots in lumbar plexus
      • Runs deep to psoas, comes lateral to psoas tendon at level of inguinal ligament
      • Lies lateral to femoral artery below inguinal ligament
        • Different fascial plane: deep to fascia lata and fascia iliaca
      • Divides into superficial and deep bundles
        • Superficial supplies anterior thigh and sartorius
        • Deep supplies quadriceps, knee joint, gives rise to saphenous nerve
    • Obturator nerve arises from L2-4
    • Lateral cutaneous nerve of thigh arises from L2-3
  • Needle placement
    • Patient supine
    • Short-bevel needle inserted 1-2 cm below inguinal ligament 1-1.5 cm lateral to femoral artery
    • Two “pops” or paraesthesia elicited or nerve stimulator used to determine depth
  • Local anaesthetic
    • Femoral nerve only
      • 10-20 ml of 0.5% bupivacaine
    • Three-in-one
      • 30 ml of solution (may need to be more dilute than 0.5% to avoid toxic dose)
      • Distal pressure over nerve causes solution to flow proximally
      • Proximal spread to lumbar plexus anaesthetizes obturator and lateral cutaneous nerve of thigh
  • Indications
    • Three-in-one may be combined with sciatic block for most leg surgery
    • Ideal for muscle biopsy in MH testing
    • Useful for knee examination and surgery
    • Analgesia for femoral fractures
  • Complications
    • Vascular
      • Femoral artery or vein injury, haematoma
    • Neurological
      • Neuropraxia, sympathetic block to leg
  • Common to all blocks
    • Local anaesthetic toxicity (esp. combined with sciatic block)
    • Poor effect
    • Infection

Sciatic block


Classic approach of Labat

  • Lateral position, upper heel on lower knee
  • Line from greater trochanter to PSIS marks upper border of piriformis
  • Bisector of this line extended 3 cm inferiorly marks injection site
    • or intersection with line from greater trochanter to sacral cornu
    • or intersection with line from midpoint of line from PSIS to ischial tuberosity to greater trochanter

  • Advance 6-8 cm until bone is contacted
  • Geometric grid approach searching for paraesthesia or using nerve stimulator

Anterior approach of Labat

  • Supine anatomical position
  • Line of inguinal ligament identified
  • Medial trisector extended inferiorly
  • Intersection with a line parallel to inguinal ligament running through greater trochanter identified
  • Needle advanced slightly laterally strikes lesser trochanter
  • Walk medially off femur and identify LOR 4.5-6 cm beyond (or use nerve stimulator)

Lithotomy approach

  • Lithotomy position with full hip flexion
  • Line from ischial tuberosity to greater trochanter
  • Needle advanced through midpoint perpendicular to skin
  • LOR or nerve stimulator or paraesthesia determine depth

Lateral approach

  • Supine position
  • Needle inserted 3 cm distal to greater trochanter at posterior border of femur
  • Advanced immediately behind femur 8-12 cm total depth
  • Nerve stimulator or paraesthesia used to determine depth

Prone (Ian McKenzie’s) approach

  • Prone position
  • Line from ischial tuberosity to head of fibula marks biceps femoris
  • Line from midpoint between ischial tuberosity and greater trochanter to middle of
  • popliteal fossa marks course of sciatic (tibial) nerve
  • Needle inserted at intersection of lines
  • LOR deep to biceps femoris

Ankle block

 

  • Saphenous n
    • Blocks postero-medial part of dorsum of foot
    • Superficial infiltration around long saphenous vein anterosuperior to medial malleolus
  • Tibial n
    • Needle entry medial to Achilles tendon or lateral to posterior tibial artery at upper border of medial malleolus
    • Determine depth with paraesthesia, nerve stimulator or 1 cm superficial to tibia
    • Alternatively infiltration either side of artery behind medial malleolus
    • Blocks sole, plantar surface of digits
  • Deep peroneal n
    • Needle entry between extensor hallucis longus and tibialis anterior tendons or lateral to anterior tibial artery
    • Blocks first web space and short toe extensors
  • Superficial peroneal n
    • Superficial infiltration from lateral border of tibia to upper part of lateral malleolus
    • Blocks dorsum of foot and toes except first web space
  • Sural n
    • Superficial infiltration from Achilles tendon to lateral malleolus
    • Blocks lateral side of foot and fifth digit

Other lower limb blocks


Lateral femoral cutaneous nerve

  • Anatomy
    • L2-3 ventral roots
    • Emerges at lateral border of psoas inferior to ilioinguinal nerve
    • Runs between iliac fascia and iliacus
    • Emerges inferomedial to ASIS from under inguinal ligament
    • Crosses origin of sartorius and runs deep to fascia lata, dividing into anterior and posterior branches
    • Supplies skin over lateral thigh
  • Needle placement
    • Patient supine
    • Short bevel needle inserted 2 cm inferior and 2 cm medial to ASIS
    • Pop felt on passing though fascia lata
  • Local anaesthetic
    • 10-15 ml placed deep and superficial to fascia lata
    • Dilute solution required if multiple blocks are to be performed
  • Indications
    • Combined with sciatic, femoral and obturator blocks for leg surgery

Obturator nerve

  • Anatomy
    • L2-4 nerve roots
    • Emerges medial to psoas at pelvic brim
    • Runs around pelvis behind iliac vessels and ureter
    • Enters obturator canal superior and anterior to obturator vessels
    • Divides in canal into anterior and posterior branches
      • Anterior branch supplies anterior adductors, hip joint and medial thigh
      • Posterior branch supplies deep adductors and knee joint
  • Needle placement
    • Patient supine, legs slightly abducted
    • Point 1.5 cm lateral and 1.5 cm inferior to pubic tubercle identified
    • Needle inserted AP, contacts superior pubic ramus at 1.5-4 cm depth
    • Walked laterally into obturator canal and advanced 2-3 cm
  • Local anaesthetic
    • 10-15 ml of dilute solution while advancing and withdrawing
  • Complications
    • Intravascular injection in obturator vessels, haematoma

Tibial and common peroneal nerves in the popliteal fossa

  • Anatomy
    • Sciatic nerve divides at apex of popliteal fossa
      • Tibial nerve continues lateral to vessels inferiorly between heads of gastrocnemius
      • Common peroneal nerve accompanies biceps femoris tendon laterally, passes around head of fibula and divides into superficial and deep branches
  • Needle placement
    • Patient prone or lateral
    • Margins of popliteal fossa identified: semimembranosus, biceps femoris and gastrocnemius
    • Point identified 1 cm lateral to midline of fossa and 5 cm superior to skin crease
    • Needle inserted angled 45°-60° anterosuperiorly, paraesthesia sought
  • Local anaesthetic
    • 30-40 ml of dilute solution
  • Indication
    • Foot and ankle surgery
    • Saphenous nerve territory not covered (femoral origin)

Blood patch

  • Technique
    • Timing
      • Probably less effective in first 24 hours
      • Must wait until block is completely resolved
    • Volume
      • No clear evidence that large volumes are better
      • Commonly 10-20 ml
    • Bed rest
      • Two hours is better than 30 min or one bour
  • Indications
    • Moderate to severe PDPH
    • Prophylactic on catheter withdrawal after dural tap on insertion (controversial)
  • Contraindications
    • Needle placement
      • Coagulopathy, sepsis, local infection, anatomical abnormality
    • Autologous blood injection
      • Sepsis
      • No adverse sequelae in HIV infection
      • Raised ICP: increased further by injection
  • Complications of PDPH
    • Cranial nerve palsies unaltered
    • Hearing loss and tinnitus markedly improved
    • Seizures uncommon, no evidence of effect
    • Intracranial bleed and  increased ICP: contraindication
  • Effectiveness
    • >90% initial relief
    • 60-75% presistent relief after large needle puncture
  • Mechanism of action
    • Pressure effect from injection
      • Brief for crystalloids, minutes to hours for blood
    • “Plug” effect from sealing dural tear
  • Effect on subsequent epidural
    • Increased risk of dural puncture and poor block
  • Prophylactic use
    • Saline 40-60 ml reduces need for blood patch

Intercostal block

  • Anatomy
    • Intercostal nerve arises from T1-T11 nerve roots, T12 is similar (subcostal)
    • Branches
      • Grey ramus communicans from sympathetic chain
      • Posterior cutaneous branch arises beyond vertebral foramen and supplies paravertebral muscles and skin
      • Lateral cutaneous branch arises anterior to midaxillary line and supplies skin of lateral aspect of chest
      • Anterior cutaneous branch pierces pectoralis major or rectus abdominis and supplies breasts and anterior chest and abdominal wall
      • T1-3 give branches to axillary plexus and intercostobrachial nerve
      • T12 gives branches to iliohypogastric and ilioinguinal nerves
    • Nerve lies deep to internal and external intercostal muscles, superficial to intercostalis intimis and pleura
    • Neurovascular bundle lies immediately inferior to rib and consists of vein, artery and nerve from superior to inferior
  • Needle placement
    • Sitting, lateral or prone positions
    • Identify line of lateral margin of paravertebral muscles (6-8 cm lateral to midline)
    • Count ribs to identify correct level
    • Apply traction superiorly to skin, insert needle over rib
    • Allow skin to retract inferiorly and walk needle off inferior edge of rib
    • Inserted another 2-5 mm with aspiration
  • Local anaesthetic
    • Long-acting agent with adrenaline
    • 2-5 ml of solution per nerve
    • Care with total dose as absorption is fairly rapid
  • Indications
    • Anaesthesia
      • Chest drain insertion, gastrostomy insertion
      • Other minor thoracic or abdominal procedures
    • Analgesia
      • Fractured ribs
      • Thoracotomy or laparotomy as adjuvant technique
  • Complications
    • Pneumothorax
      • Rare despite risks of entering pleura as the needle used is small
      • Managed conservatively
    • Local anaesthetic toxicity
      • Minimize with adrenaline-containing solution

Paravertebral block

  • Anatomy
    • Similar to intercostal block but placement 2 cm lateral to midline
  • Needle placement
    • Needle inserted postero-anteriorly onto transverse process
    • Walked off top or bottom of process and inserted 1 cm
    • “Hanging drop” can be used
    • Inject at every level or else rely on spread between levels
  • Local anaesthetic
    • Divide total dose between number of levels
  • Indications
    • Breast surgery, other surgery requiring unilateral block

Brachial plexus

  • Five nerve roots
    • C5-8 branches to longus colli and scaleni
    • C5-7 branch to long thoracic n.
    • C5 contributes to phrenic n. and dorsal scapular n.
  • Three trunks
    • Form between scalenus medius and scalenus anterior
    • Superior, middle and inferior
    • Superior gives off suprascapular n.
    • Inferior gives off first intercostal n.
    • Divide into ventral and dorsal divisions at lateral edge of first rib
  • Six divisions
    • Dorsal divisions supply extensors
    • Ventral divisions supply flexors
    • Form cords on entering the axilla
  • Three cords
    • Lateral, posterior and medial
    • Axillary artery lies between
    • Posterior gives off five extensor branches
      • Two major: radial and axillary nn.
      • Three minor: thoracodorsal and two subscapular nn.
    • Lateral gives off three branches
      • Two major: musculocutaneous n. and half of median n.
      • One minor: lateral pectoral n.
    • Medial gives off five branches
      • Two major: ulnar and half of median n.
      • Three minor: medial pectoral and medial cutaneous nn. of arm and forearm

Interscalene block

  • Anatomy
    • Trunks of brachial plexus cross first rib behind scalenus anterior and subclavian artery at the level of C6
  • Needle placement
    • Patient supine with head turned away
    • Interscalene groove is palpable at the level of cricoid cartilage or Chassaignac’s tubercle
    • Needle inserted with slight posteroinferior angulation
    • Walked posteriorly in C6 plane if required to elicit paraesthesia or twitches
  • Local anaesthetic
    • 30-40 ml of lignocaine 2% or bupivacaine 0.5%
  • Indications
    • Most reliable from C4-C7
    • Shoulder surgery, reduction of dislocated shoulder
    • Supplementation required for hand of forearm surgery
      • More caudal needle placement to cover C8-T1/ulnar distribution
  • Complications
    • Phrenic nerve block common
    • Subarachnoid or epidural injection
    • Intravascular injection (subclavian or vertebral artery)
    • Pneumothorax

Supraclavicular block

  • Anatomy
    • Plexus lies inferior to mid-clavicle
    • Subclavian artery is anterior and medial to the plexus
    • Both pass over the first rib together
  • Needle placement
    • Classical approach
      • Relatively difficult to describe and teach
      • Patient supine, arm at side, head turned away
      • Interscapular roll and inferior displacement of the shoulder can make it easier
      • Interscalene groove identified by palpation posterior to sternocleidomastoid
      • Subclavian artery is often palpable behind clavicle
      • Needle inserted 2 cm behind midpoint of the clavicle or immediately posterior to the artery
        • Lateral end of clavicle is medial to the acromion
      • Directed inferiorly with slight posteromedial angulation
      • Paraesthesia or nerve-stimulator indicates location at the plexus
      • If no paraesthesia is elicited, the superior surface of the first rib is usually contacted
      • Walking anteriorly along the rib surface should result in paraesthesia
    • “Plumb-bob” approach
      • Patient supine, head turned away
      • Lateral margin of insertion of sternocleidomastiod into clavicle identified
      • Needle inserted directly anteroposterior
      • Angled superiorly and then inferiorly until paraesthesia elicited
    • Sternocleidomastoid approach
      • 10 cm needle inserted at junction of clavicular and sternal heads of sternocleidomastoid
      • Directed posterolaterally aiming at posterior of midpoint of clavicle
      • Nerve stimulator indicates plexus
  • Local anaesthetic
    • 15-25 ml of lignocaine, bupivacaine or ropivacaine
    • Periodic aspiration
  • Indications
    • Most reliable from C5-T1
    • Most upper limb surgery
      • Proximal block: compact plexus, above most branches, small volume required
    • Shoulder surgery may require supplemental cervical plexus block for overlying skin
  • Complications
    • Pneumothorax
      • 0.5-6.0% in different series
      • Usually small and managed conservatively
    • Phrenic nerve block
      • 40-60%, usually asymptomatic
    • Stellate ganglion block
      • Increased incidence with volume of anaesthetic
      • Up to 90% with 50 ml of solution
      • Horner’s syndrome
    • Vascular injury
    • Local anaesthetic toxicity

Axillary

  • Anatomy
    • Brachial plexus has formed terminal branches in the axilla
    • Musculocutaneous lies in coracobrachalis
    • Median, ulnar and radial nerves lie in close relation to the axillary artery from superficial to deep
    • Fascial septa divide the branches of the plexus at this level
  • Needle placement
    • Patient supine with arm abducted to 90°, externally rotated and flexed 90° at the elbow
    • Course of the axillary artery determined by palpation
    • Skin wheal and needle insertion adjacent to artery
    • Paraesthesia or twitching elicited in appropriate nerves
    • Alternatively LA deposited in all quadrants around artery
    • Infiltration in mass of coracobrachialis to block musculocutaneous n.
  • Local anaesthetic
    • 20-30 ml of lignocaine or bupivacaine with adrenaline
    • Hyaluronidase, bicarbonate for more rapid spread (but less duration)
  • Indications
    • Most reliable from C7-T1
    • Best for distal limb surgery (hand or forearm)
    • Suitable for indwelling catheter placement
  • Complications
    • Intravascular injection (axillary artery or vein)
    • Haematoma and plexus compression

Elbow

  • Median
    • Anatomy
      • Lies medial to brachial a. where it emerges medial to biceps tendon
    • Needle placement
      • Arm supinated and extended at the elbow
      • Plane of epicondyles of humerus identified
      • Brachial artery palpated
      • Needle insertion immediately medial to artery
    • Local anaesthetic
      • 3-5 ml of lignocaine 1% or bupivacaine 0.25%
  • Radial
    • Anatomy
      • Pierces lateral intermuscular septum above the elbow
      • Lies between brachialis and brachioradialis
    • Needle placement
      • Position and level as for median nerve
      • Point 2 cm lateral to biceps tendon
    • Local anaesthetic
      • Fan-like injection of 4-6 ml
  • Ulnar
    • Anatomy
      • Nerve runs behind medial epicondyle
      • In groove between epicondyle and olecranon
    • Needle placement
      • Elbow in full flexion
      • Epicondyle identified
      • Needle inserted 1 cm proximal to epicondyle (not in groove)
    • Local anaesthetic
      • 3-5 ml lignocaine 1% or bupivacaine 0.25%
  • Medial cutaneous nerve of forearm
    • Anatomy
      • Continuation of musculocutaneous nerve
      • Ramifies superficially over medial forearm
    • Needle placement
      • Infiltration in a band across medial forearm one third of the way from elbow to wrist
    • Indications
      • Supplementation of brachial plexus block with inadequate cover
      • Not commonly used alone

Wrist

  • Median
    • Anatomy
      • Lies deep to and between FCR and palmaris longus tendons
      • Inside carpal tunnel
    • Needle placement
      • Line from ulnar styloid to distal tip of radius identified
      • Needle inserted on this line between FCR and palmaris longus
      • Flexor retinaculum penetrated
    • Local anaesthetic
      • 3-5 ml, plain solution probably advisable
  • Radial
    • Anatomy
      • Already divided into terminal branches at the wrist
      • Spread over radial and dorsal aspect of the wrist
    • Needle placement
      • Infiltration over anatomical snuff-box and further medially
      • Superficial to EPL
    • Local anaesthetic
      • 5-6 ml
  • Ulnar
    • Anatomy
      • Lies lateral to FCU and medial to ulnar a.
      • Has already given off palmar cutaneous and dorsal braches
      • Divides into deep motor and superficial sensory braches at the level of pisiform
    • Needle placement
      • Approach from anterior or medial aspect just proximal to pisiform
      • Medial approach allows infiltration to all branches from one puncture
    • Local anaesthetic
      • 3-5 ml plus infiltration
  • Indications
    • Supplementation of brachial plexus block with inadequate cover
    • Not commonly used alone

Complications of retrobulbar and peribulbar eye blocks

  • Complications of any block
    • Needle
      • Local pain
    • Drug
      • Systemic local anaesthetic toxicity
      • Allergy, anaphylaxis
    • Technique
      • Failure of aseptic technique: cellulitis, ophthalmitis, meningitis
      • Failure of block: pain intraoperatively or postoperatively
  • Complications of eye blocks
    • Vessels
      • Retrobulbar haemorrhage, retinal vascular occlusion, optic nerve trauma, late optic atrophy
        • Variable presentation: arterial vs venous haemorrhage
        • More common with large needle insertion in vascular areas e.g. superonasal
        • Microvascular disease increases risk of ischaemia e.g. diabetes
        • Manage with local pressure, IOP measurement, IOP reduction measures, surgical decompression if necessary
        • Haemorrhage within the optic nerve sheath results in rapid ocular venous congestion
      • Intravascular injection
        • Retrograde flow with rapid injection
        • Injection of antibiotics or steroids by the surgeon can also be intravascular, causing embolism
    • Nerve
      • Optic nerve injection
      • Injury to III, IV or VI uncommon
      • Other cranial nerve block related to facial nerve block at stylomastoid foramen
        • Vagus, glossopharyngeal block
        • Swallowing difficulty, respiratory obstruction
      • Brainstem anaesthesia
        • Associated with long, sharp needles
        • Onset over 2 to 20 minutes, lasts up to three hours
        • Symptoms highly variable: unconsciousness to isolated nerves or nuclei blocked
        • Contralateral eye signs one of the earliest markers
      • Atonic pupil
        • One case related to ciliary ganglion needle damage
        • More commonly direct trauma
        • Test with pilocarpine
    • Muscle
      • Extraocular muscle dysfunction
        • Block duration up to 48 h with bupivacaine or ropivacaine
        • Longer duration suggests nerve or muscle damage
        • Most commonly intramuscular injection which resolves over weeks
      • Persistent ptosis
        • Common in cataract patients regardless of surgery
        • May be intramuscular injection or bridle suture damage
          • Extraocular muscle injection may cause muscle rupture and diplopia
    • Globe
      • Ocular penetration and perforation
        • More common in long eyes
        • High myopes for retinal surgery or radial keratotomy
        • Prevention
          • Known axial length, open eye during needle placement, avoiding displacement of the globe into the path of the needle
        • Commonly accompanied by pain, retinal detachment, haemorrhage
      • Corneal injury
        • Careful attention to padding and taping the anaesthetic eye
      • Ischaemia related to Honan's balloon or other compression device
      • Suprachoroidal haemorrhage
        • Related to hypertension
        • May be secondary to coughing or full bladder
      • Sympathetic ophthalmia
    • Reflex
      • Oculocardiac reflex
        • Bradycardia after injection
        • May persist longer than during surgery
        • Most common in children and young adults
        • Treat with atropine or glycopyrrolate

Ear

  • Anatomy
    • Cervical plexus branches greater auricular and lesser occipital supply posterior surface of auricle and lower third of anterior surface
    • Greater auricular also supplies posterior part of external canal
    • Auriculotemporal branch of mandibular division of trigeminal nerve supplies superior two thirds of anterior surface
    • Auriculotemporal also supples superior part of external canal
    • Auricular branch of vagus supplies inferior part of external canal
    • Tympanic branch of glossopharyngeal and facial nerve supplies drum
  • Needle placement
    • Superficial cervical plexus block or infiltrate over mastoid for cervical plexus branches
    • Infiltrate at posterior aspect of zygoma for auriculotemporal block
    • Canal supply from exterior blocked by infiltration at junction of bony and cartilaginous parts
    • Drum anaesthetized with topical lignocaine spray 4-10%

Nose

  • Anatomy
    • Trigeminal nerve, ophthalmic division (V1), nasociliary nerve, anterior ethmoidal and external nasal branches to bridge and tip and superior and anterior parts of septum and lateral wall
    • Trigeminal nerve, maxillary division (V2), infraorbital nerve, nasal branches to remainder of external nose
    • V2 pterygopalatine ganglion, nasopalatine branch to posterior and inferior septum
    • V2 anterior superior alveolar branch to anterior and inferior lateral wall
    • V2 pterygopalatine ganglion, posterior and inferior nasal branches to posterior and superior lateral wall
    • V2 pterygopalatine ganglion, greater palatine nerve to posterior and inferior lateral wall
  • Needle placement
    • External nose: supraorbital notch & medially, infraorbital foramen, junction of nasal bone and cartilage all infiltrated
    • Cavity
      • Topical or soaked cotton bud applied to anterior ethmoidal by inserting along the line of the external nose until it reaches a superior limit
      • Same applied to sphenopalatine ganglion by insertion at 20°-30° to horizontal
      • Floor anaesthetized with topical local

Trigeminal nerve

  • Ganglion
    • Anatomy
      • Ganglion is intracranial in Meckel’s cave, a reflection of dura
      • Closely related to superior orbital fissure, foramen rotundum, and foramen ovale through which branches leave the skull
      • Foramen ovale is in the horizontal plane of zygoma, vertical plane of mandibular notch, dorsolateral to pterygoid process
    • Needle placement
      • Skin wheal at anterior border of masseter, 3 cm lateral to corner of mouth, opposite second upper molar
      • 10 cm needle advanced in plane of the pupil, superiorly, medially and posteriorly
      • Contact with inferior surface of greater wing of sphenoid at 4.5-6 cm
      • Walked posteriorly along sphenoid until enters foramen ovale, 1-1.5 cm beyond first bony contact
    • Local anaesthetic
      • 1-3 ml of any solution injected in small aliquots with aspiration
    • Indications
      • Facial neuralgias
      • Major facial surgery in patient unable to receive GA
    • Complications
      • Technically difficult
      • Subarachnoid injection of LA
        • Unconsciousness reported with 0.25 ml of 1% lignocaine
      • Local pain, haematoma formation

Maxillary nerve

  • Anatomy
    • Leaves the cranium though the foramen rotundum, deep to the pterygoid plate
    • Passes through the pterygopalatine fossa
    • Enters the floor of the orbit through the inferior orbital fissure
    • Emerges throught the infraorbital foramen
  • Needle placement
    • Skin wheal over mandibular notch
    • 8 cm needle inserted superomedially through mandibular notch
    • Strikes lateral pterygoid plate at 5 cm depth
    • Walked off anterior margin of lateral pterygoid plate into pterygopalatine fossa
    • Inserted 1 cm into pterygopalatine fossa
  • Local anaesthetic
    • 5 ml of any solution
  • Indications
    • Facial neuralgia
  • Complications
    • Vascular region of insertion --> haematoma formation
    • Close proximity to infraorbital fissure
      • Disturbance of eye movement or vision
      • “Black eye” from haematoma formation

Mandibular nerve

  • Anatomy
    • Leaves the cranium through the foramen ovale, posterior to lateral pterygoid plate
    • Divides into anterior and posterior divisions
    • Anterior division is motor supply to muscles of mastication, sensory to buccal branch
    • Posterior division is motor to *** sensory: auriculotemporal, lingual and inferior alveolar nerves
  • Needle placement
    • Skin wheal over mandibular notch
    • 8 cm needle inserted superomedially through mandibular notch
    • Strikes lateral pterygoid plate at 5 cm depth
    • Walked posteriorly off lateral pterygoid plate
    • Advanced only 0.5 cm to avoid superior constrictor, pharynx
  • Local anaesthetic
    • 5 ml of any solution
  • Indications
    • Facial neuralgia
    • Dental work (usually transmucosal approach)
  • Complications
    • Haematoma
    • Injury to the superior constrictor, entering the pharynx

Other head and neck


Greater occipital nerve

  • Anatomy
    • Greater occipital n. is the dorsal ramus of C2
    • Emerges over atlas, deep to cervical musculature
    • Becomes subcutaneous near superior nuchal line
    • Immediately medial to occipital a.
    • Supplies sensation to posterior scalp to vertex
  • Needle placement
    • Patient sitting with neck flexed
    • Superior nuchal line from occipital protuberance to mastoid
    • Nerve lies approximately at medial 1/3 point, near artery
    • Infiltration of 3-5 ml around artery
  • Indications
    • Occipital tension headache, diagnostic aid
  • Complications
    • Low risk block

Cervical plexus

  • Anatomy
    • Formed by ventral rami of C1-4
    • Direct motor branches to prevertebral muscles
    • Cutaneous branches form “superficial” plexus
      • Lesser occipital, greater auricular, transverse cervical and supraclavicular nerves
      • Emerge from behind the midpoint of sternocleidomastoid
    • Ansa cervicalis innervates infrahyoid and geniohyoid muscles
    • Phrenic nerve (C3-5) is central sensory and sole motor supply to diaphragm
      • Emerges lateral to scalenus anterior and enters the thorax medial to it
    • Contribution to CN XI motor supply to sternocleidomastoid and trapezius
  • Needle placement
    • Deep
      • Patient in supine position with head turned away
      • Line drawn 1 cm posterior to line from mastoid to Chassaignac’s tubercle (transverse process of C6)
      • C2 transverse process palpable 1.5 cm inferior to mastoid
      • C3 and C4 transverse processes identified relative to C2 and C6
      • Needles placed on transverse processes of C2-4
        • Withdrawn 1-2 mm off bone
        • Caudad angulation to reduce chance of entering foramina
        • Aspiration to check for vertebral artery puncture
    • Superficial
      • Short bevelled needle inserted posterior to midpoint of sternocleidomastoid
      • Injection immediately deep to superficial cervial fascia
      • Infiltration along posterior border of sternocleidomastoid superiorly and inferiorly
  • Local anaesthetic
    • Deep
      • 15-20 ml of lignocaine 1.5% or ropivacaine 0.75%
    • Superficial
      • 15 ml of lignocaine 1.5% or ropivacaine 0.75%
  • Indications
    • Carotid endarterectomy, lymph node biopsy, plastic surgery to neck
  • Complications
    • Deep
      • Phrenic nerve block, hypoventilation
      • Vertebral artery injection, convulsions
      • Dural sheath injection, total spinal
    • Superficial
      • External or internal jugular vein injection

Stellate ganglion

  • Anatomy
    • Cervical sympathetic trunk is a continuation of the thoracic sympathetics
      • Lies anterior to cervical transverse processes
      • Composed of three ganglia
        • Superior cervical ganglion opposite C1
        • Middle cervical ganglion opposite C6
        • Stellate ganglion opposite C7-T1
          • Commonly closely related to subclavian and vertebral arteries
  • Needle placement
    • Patient supine with neck extended
    • Chassaignac’s tubercle identified (at level of cricoid cartilage)
    • Firm palpation medial to carotid artery either side of C6 transverse process
    • Short needle inserted onto transverse process of C6 directly A-P
    • Withdrawal 1-2 mm before injection
  • Local anaesthetic
    • 5-10 ml of 0.25% bupivacaine with adrenaline
    • Frequent aspiration
  • Indications
    • Complex regional pain syndrome of upper limb
    • Poor perfusion of upper limb
  • Complications
    • Vertebral artery injection, convulsions
    • Blockade of recurrent laryngeal or phrenic nerves

Airway

Principles

  • Trigeminal
    • Nasopharynx down to soft palate
    • Maxillary division
  • Glossopharyngeal
    • Soft palate to epiglottis
    • Pharyngeal nerves to pharyngeal mucosa
    • Tonsillar nerves to tonsils and soft palate
    • Posterior third of tongue
  • Vagus
    • Below epiglottis
    • Superior laryngeal nerve arises from inferior ganglion of vagus
      • Crosses cornu of hyoid and divides into internal and external laryngeal branches
      • Internal branch penetrated thyrohyoid membrane and innervates mucosa from epiglottis to cords
      • External branch supplies cricothyroid m.
    • Vagus gives off recurrent laryngeal nerve below aorta (L) or subclavian a. (R)
      • Penetrates cricothyroid membrane laterally and innervates the mucosa below the cords and muscles of the larynx

Glossopharyngeal nerve

  • Anatomy
    • Exits the skull through the jugular foramen lateral to X, ICA and IJV, anterior to XII and XI
    • Descends in the carotid sheath, passes between ICA and ECA before branching
    • Branches lie submucosally posterior to tonsil, deep to posterior tonsillar pillar
  • Needle placement
    • Intraoral route
      • Mouth opened with laryngoscope, topical anaesthesia to tongue and tonsil
      • 9 cm curved needle inserted submucosally in caudal part of posterior tonsillar pillar
      • Careful aspiration for blood (ICA is adjacent)
    • Peristyloid route
      • Patient supine, head in neutral position
      • Line from mastoid to angle of jaw identified
      • Skin wheal at midpoint of line, styloid may be palpable
      • Short needle inserted medially to contact styloid
      • Walked off posterior aspect of styloid
      • Careful aspiration of blood (IJV and ICA)
  • Local anaesthetic
    • 5-7 ml of lignocaine 0.5%
  • Indications
    • Awake intubation
  • Complications
    • Intravascular injection, convulsions

Superior laryngeal nerve (internal br.)

  • Anatomy
    • Leaves the vagal trunk above the hyoid
    • Crosses the cornu of the hyoid
    • Penetrates the thyrohyoid membrane inferior to the hyoid
      • Accompanied by superior laryngeal artery and vein
  • Needle placement
    • Patient supine with neck extended
    • Hyoid displaced toward side of block
    • Skin wheal over greater cornu
    • Needle inserted medially to make contact with greater cornu
    • Walked inferiorly off cornu and advanced 2-3 mm
      • Should lie between thyrohyoid membrane and laryngeal mucosa
  • Local anaesthetic
    • 3-4 ml of lignocaine 0.5%
  • Indications
    • Awake intubation
  • Complications
    • Entering the larynx, coughing with injection
    • Intravascular injection is uncommon

Translaryngeal block

  • Needle placement
    • Needle or IV cannula inserted in midline through cricothyroid membrane until air is aspirated
  • Local anaesthetic
    • 3-4 ml of lignocaine 4% topical solution rapidly injected and needle withdrawn before coughing

Recipes for regional anaesthesia

  • Eye block (Royal Victorian Eye and Ear Hospital)
    • Lignocaine 10% 2 ml
    • Bupivacaine 0.5% or ropivacaine 1.0% 7 ml
    • Hyalase 150 U in 1 ml bupivacaine 0.5% or ropivacaine 1.0%
    • Oxybuprocaine topical to conjunctiva
    • 30g 12 mm medial canthus 2-3 ml
    • 27g 32 mm inferotemporal 3-4 ml
  • Bier’s
    • Prilocaine 0.6% 40 ml
    • Prilocaine 0.5% 0.5 ml/kg (2.5-3.0 mg/kg)
    • Lignocaine 2-3 mg/kg
  • Interscalene
    • 15-20 ml
  • Supraclavicular to axillary
    • 30-40 ml
  • Cervical
    • Lignocaine 1.5% with adrenaline
      • ± Ropivacaine
    • Superficial 15 ml
    • Deep 5-7 ml x 3
  • Caudal (Royal Children’s Hospital)
    • Bupivacaine 0.25% 0.5-1 ml/kg
    • Bupivacaine 0.5% 0.5 ml/kg up to 20ml
    • Add clonidine 2 μg/kg
  • Spinal
    • LUSCS (Mercy Hospital for Women)
      • Bupivacaine 0.5% heavy 2.2 ml (2-2.5)
      • Fentanyl 15 μg or morphine 100 μg
    • Manual removal (MHW)
      • Bupivacaine 0.5% plain 1.2 ml (1.2-2)
      • Fentanyl 15 μg
    • Neonatal for hernia repair(RCH)
      • bupivacaine 0.5% plain 0.2 ml/kg, min 0.4ml
    • THJR
      • Bupivacaine 0.5% plain 3-4 ml
      • D Williams: bupivacaine 0.5% plain 2 ml, midazolam 2 mg, morphine 250 μg
    • Knee scope, ESWL, other short procedures
      • Procaine 2% 5 ml
  • CSE
    • Labour (MHW)
      • Bupivacaine 0.5% plain 0.5 ml
      • Fentanyl 25 μg
      • Epidural
    • Labour (MHW)
      • Bupivacaine 0.25% 6-10 ml
      • Fentanyl 100 μg
      • Plus infusion 0.1% bupivacaine, 2 μg/ml fentanyl 10 ml/h
    • Labour PCEA (MHW)
      • Bupivacaine 0.125%, fentanyl 5 μg/ml 15 ml + 5 ml if inadequate at 15 min
      • Bupivacaine 0.625%, fentanyl 2 μg/ml 5 ml bolus, 10 min lockout
    • LUSCS (MHW)
      • Lignocaine 2% up to 20ml
      • Fentanyl 100 μg or pethidine 50 mg or morphine 3-4 mg
    • Paediatric (RCH)
      • Bupivacaine 0.125% ≈0.25 ml/kg/h
      • ± Fentanyl or clonidine 2 μg/ml
Kindly provided by Dr James Mitchell from his pharmacodynamics series

ArticleDate:20061023
SiteSection: Article
 
   
    
                                            
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