Regional Anaesthesia

Dr Reema Ayyash ST7 James Cook University Hospital Overview

• Past SAQs • Anatomy and techniques for common blocks • MCQ & SBA session • Hot topics • For nerve bloc videos: http://www.nysora.com

For any nerve block question

Preparation • Pre-operative assessment and consent • Aseptic technique • Full monitoring as per AAGBI guidelines • IV access • Resuscitation equipment available • Trained assistant • Correct equipment available: needle, PNS, US • Calculated dose of local anaesthetic

September 2014 a) Outline the basic principles of ultrasound signal and image generation. (6 marks) b) How may physical factors influence the image quality of an ultrasound device? (6 marks) c) Which two needling techniques are commonly used in ultrasound guided nerve blocks and what are the advantages and disadvantages of each? (8 marks)

Pass Rate 5.7%

“The very poor scores for this question were surprising given the widespread use of ultrasound imaging in current clinical practice” “ Eight marks were attainable for discussing two types of needling technique, hence this question was deemed to be moderately difficult and not hard. Despite this, many candidates failed to score more than five marks.” “ A “black box” approach was evident in the written answers and examiners questioned whether the candidates had any knowledge of the factors which affect the generation of a good quality ultrasound image.” “Previous reports from the SAQ Group Chair have emphasised that knowledge acquired in preparation for the Primary FRCA examination can be tested in any element of the Final FRCA process. This advice seems to have been largely ignored. The question was of moderate discriminatory value as ignorance of the topic was widespread within the candidate cohort.”

a) Outline the basic principles of ultrasound signal and image generation. (6 marks)

• Based on sound waves that are transmitted from, and received by, an US transducer • The transducer utilises frequencies of 2– 15 MHz • Transducers use artificial polycrystalline ferroelectric materials (ceramics) which have piezoelectric properties • Relies on piezo-electric effect: based on the conversion of sound to electrical energy • This allows the transducer to act as both a sound transmitter and receiver • Ultrasound waves are generated by a piezoelectric crystal transducer encased in the probe

a) Outline the basic principles of ultrasound signal and image generation. (6 marks)

• A high frequency alternate voltage is applied to the crystal

• This changes the shape of the crystals generating oscillations • The generated sound waves are propagated into the tissues and are either reflected or scattered at the tissue interface • The reflected portion returns to the probe where it distorts the transducer material • This creates an electrical charge which is then amplified and displayed on a monitor to produce an image

• Hyperechogenic: Highly reflective tissue e.g. bone – appear white • Hypoechogenic: Poorly reflective tissue e.g. muscle – appear grey • Anechogenic: Do not reflect at all e.g. blood/air – appear black

a) Outline the basic principles of ultrasound signal and image generation. (6 marks)

Amplitude mode (A mode): displays a single echo signal against time to measure depth

Brightness modulation (B mode): A 2D image using multiple beam positions and a series of reflected echoes, producing a black and white image similar to an anatomical slice

a) Outline the basic principles of ultrasound signal and image generation. (6 marks)

Motion mode (M mode): M- line ensonified repeatedly to examine a moving structure. Plots how the structure moves with time

b) How may physical factors influence the image quality of an ultrasound device? (6 marks)

Tissue interaction

• Ultrasound images produced depend on: • Density of tissue imaged • Echogenicity • Axial resolution: refers to the ability to distinguish two structures that lie along the axis (i.e. parallel) of the ultrasound beam as separate and distinct. • High frequency = low pulse duration thus better axial resolution • Acoustic impedance: determines the amount of ultrasound reflected in the media/tissue

b) How may physical factors influence the image quality of an ultrasound device? (6 marks)

Tissue interaction

Attenuation

b) How may physical factors influence the image quality of an ultrasound device? (6 marks)

Tissue interaction

Refraction Scattering

b) How may physical factors influence the image quality of an ultrasound device? (6 marks)

Tissue interaction

Speckle Diffraction

b) How may physical factors influence the image quality of an ultrasound device? (6 marks)

Phenomena

Anisotropy Acoustic enhancement

b) How may physical factors influence the image quality of an ultrasound device? (6 marks)

Phenomena

Artifact Acoustic Shadowing

b) How may physical factors influence the image quality of an ultrasound device? (6 marks)

Phenomena

Reverberation

c) Which two needling techniques are commonly used in ultrasound guided nerve blocks and what are the advantages and disadvantages of each? (8 marks)

Out of plane technique

• Needle insertion perpendicular to transducer with the needle being identified as a hyperechoic dot on the screen as it crosses the beam

Advantages: • Used when a short needle to nerve distance exists as this may minimize patient discomfort

c) Which two needling techniques are commonly used in ultrasound guided nerve blocks and what are the advantages and disadvantages of each? (8 marks)

Disadvantages:

• Accurate identification of needle tip challenging increasing risk of misplacement

c) Which two needling techniques are commonly used in ultrasound guided nerve blocks and what are the advantages and disadvantages of each? (8 marks)

In-plane technique

• Preferred technique • Needle inserted parallel to the transducer and ultrasound beam allowing visualization of the needle shaft and tip throughout the procedure

Advantages: • Insertion angle of needle relative to probe is fairly superficial making it very useful for superficial nerve blocks

c) Which two needling techniques are commonly used in ultrasound guided nerve blocks and what are the advantages and disadvantages of each? (8 marks)

Advantages:

• Needle visualization is better with accurate needle tip placement thus increasing potential for block success and limiting complications

Disadvantages: • At steep angles identification of needle tip can be difficult with increased refraction/decreased reflection of ultrasound waves • Increased needle to nerve distance may result in increased patient discomfort September 2010

What are the a) cardiovascular (25%), b) respiratory (20%), c) gastrointestinal (20%) and d) haematological (25%) potential benefits of local anaesthetic neuraxial blockade?

Pass Rate 21%

“Neuraxial blockade is a foundation of anaesthetic practice and the poor performance in this question was surprising.” “Feedback from examiners suggests that the main reason for the poor performance in this question was not considering the potential benefits of neuraxial blockade through the entire perioperative period. “

Cardiovascular

• Improved coronary blood flow - reduced risk of myocardial ischaemia • Myocardial oxygen supply:demand ratio is improved by reduction of sympathetic activity and reduced thrombotic tendency • Patients with underlying cardiac disease appear to have a better cardiac outcome with lower catecholamine levels and reduced cardiac workload Respiratory

• Improved pulmonary function particularly in patients with a poor pre-op pulmonary function • Improved lung mechanics • Reduced incidence of post-op atelectasis and therefore pulmonary infection • Reduced side effects of opioid analgesia – respiratory depression • Allows patients to comply with physio – deep breathing and coughing Gastrointestinal

• Improved intestinal motility • Blocking of nociceptive and sympathetic reflexes • Limiting use of opioids and therefore post-op ileus • Reduced side effects of opioids – nausea/vomiting/ileus • Reduced hyperglycaemic response to surgery Haematological

• Decreased incidence of post-op DVT by: • Improved systemic blood flow • Decreased platelet stickiness • Decreased inhibition of fibrinolysis • Increased mobility post-op • Improved graft survival in vascular patients • Reduced intra-operative blood loss and therefore blood transfusions April 2002 a) Draw a diagram of the lumbar plexus. b) Outline the anatomical basis of a ‘3 in 1’ block c) Explain why the block may fail to provide reliable analgesia for hip surgery? a) Draw a diagram of the lumbar plexus.

Anterior and Posterior Cutaneous Innervation of Lumbar Plexus

Lumbar Plexus Block

Patient Position • Lateral decubitus position • Side to be blocked uppermost

Landmark • Posterior superior iliac crest • Spinous process (midline) • Posterior superior iliac spine • 50-100mm needle insertion site is 3-5 cm lateral intercristal line

Lumbar Plexus Block

Technique

• Needle inserted perpendicular to skin

• Nerve stimulator set initially to 1.5 mA

• Needle advanced until twitches of quadriceps muscle is obtained (depth 6-8cm)

• Current then decreased to 0.5- 1.0mA to produced stimulation

• After negative aspiration, inject LA

Lumbar Plexus Block: Complications

• Infection: psoas abscess • Vascular puncture • Retro-peritoneal haematoma formation • Damage to abdominal viscera • Nerve injury and intra-neural injection • Haemodynamic consequences: spinal/epidural spread • Local anaesthetic toxicity

b) Outline the anatomical basis of a ‘3 in 1’ block

• 3 in 1 = Single injection which aims to block • Femoral nerve • Obturator nerve • Lateral femoral cutaneous nerve

• Uses the same technique as the femoral nerve block, however • Larger volume of local anaesthetic injected 30-40mls • Distal compression is performed as the local anaesthetic is being injected to force the solution cranially towards the lumbar plexus into the psoas compartment c) Explain why the block may fail to provide reliable analgesia for hip surgery?

• The obturator nerve has a more variable location as it passes to the pelvis • It is separated from femoral and lateral femoral cutaneous nerve by the psoas muscle • This is why the “3-in-1 block” often fails to successfully block the obturator nerve October 2008 a) Describe the surface anatomical landmarks for (i) the anterior (Beck’s) and (ii) one posterior approach to sciatic nerve block. (50%) b) What practical advantages and disadvantages would you consider when choosing between these two approaches in an individual patient? (20%) c) List the complications that may result from this block. (20%)

Sciatic Nerve Anatomy

• Largest nerve in body supplying lower limb • Arises from sacral plexus L4-S3 • Exits pelvis through greater sciatic foramen • Passes between the ischial tuberosity and greater trochanter of the femur • Runs down the posterior aspect of the thigh • In the popliteal fossa it divides into tibial and common peroneal nerve

Sciatic Nerve Anatomy

Nerve Supply

Motor • Posterior thigh muscles and biceps femoris • Supplies NO structures in the gluteal region

Sensory • Skin of the leg and foot below the knee except for the medial calf

a) Describe the surface anatomical landmarks for (i) the anterior (Beck’s) and (ii) one posterior approach to sciatic nerve block. (50%)

ANTERIOR APPROACH Patient lies supine

Landmarks: • Line 1 is drawn from the anterior superior iliac spine to the pubic tubercle • Line 2 is parallel to line 1 from the greater trochanter to the medial border of the thigh a) Describe the surface anatomical landmarks for (i) the anterior (Beck’s) and (ii) one posterior approach to sciatic nerve block. (50%)

ANTERIOR APPROACH • At the junction of the medial and middle thirds a perpendicular line is dropped to meet line 2 • At this junction, a 150mm needle is inserted perpendicular to the skin and directed posteriorly until it contacts the medial shaft of the femur (lesser trochanter) a) Describe the surface anatomical landmarks for (i) the anterior (Beck’s) and (ii) one posterior approach to sciatic nerve block. (50%)

ANTERIOR APPROACH • When the lesser trochanter is met, the needle is withdrawn slightly and redirected to pass under the medial border of the femur, usually advanced 2-3cm further (average depth 10-13cm) • Aspirate to check for intravascular injection a) Describe the surface anatomical landmarks for (i) the anterior (Beck’s) and (ii) one posterior approach to sciatic nerve block. (50%)

POSTERIOR APPROACH Patient lies in lateral position Lower leg kept straight Upper leg is flexed at the knee

Landmarks: • A 1st line is drawn from the greater trochanter to the posterior superior iliac spine • A 2nd line is drawn from the Greater trochanter to sacral hiatus (Winne’s modification) a) Describe the surface anatomical landmarks for (i) the anterior (Beck’s) and (ii) one posterior approach to sciatic nerve block. (50%)

POSTERIOR APPROACH • At the lines’ midpoint, a perpendicular line is dropped caudally by 3-5cm • A 4th line is drawn along the “furrow” formed by the medial edge of gluteus maximus and along the head of biceps femoris • Triangle formed by the 1st, 2nd and 4th lines identifies the point of needle insertion

b) What practical advantages and disadvantages would you consider when choosing between these two approaches in an individual patient? (20%)

ANTERIOR APPROACH

Advantages Disadvantages

• Performed supine – more • Advanced nerve block, associated comfortable for patient with patient discomfort as the needle must traverse multiple muscle planes on its way to sciatic nerve (deeper block) • Needle can become obstructed with tissue debris • Sedation maybe required • Onset time 20-30min depending on type and conc of LA used • Difficult to insert catheter for continuous infusion due to perpendicular angulation of needle

b) What practical advantages and disadvantages would you consider when choosing between these two approaches in an individual patient? (20%)

POSTERIOR APPROACH

Advantages Disadvantages

• Readily identifiable landmarks in • Significant discomfort as needle most people traverses gluteus muscle • Onset time less at 10-25 minutes • Sedation maybe required • Catheter easily inserted for • Skin highly mobile therefore continuous infusion palpating hand should not be moved during entire procedure • Requires positioning in lateral decubitus position (trauma patients with uncleared or unstable spines therefore ruled out) c) List the complications that may result from this block. (20%)

• Failure • Drug error • Nerve damage • Intravascular injection • Local anaesthetic toxicity • Vascular puncture • Haematoma - avoid multiple needle insertions particularly in patients receiving anticoagulation therapy • Infection • Neuronal ischaemia

Femoral Nerve: Anatomy

• Formed by dorsal divisions of anterior rami of L2–L4 • Largest terminal branch of lumbar plexus • Travels through psoas muscle and leaves the psoas at its lateral border • It then descends caudally into the thigh via the groove formed by the psoas and iliacus muscles, entering the thigh beneath the inguinal ligament Femoral Nerve: Anatomy

• After emerging from the ligament, the femoral nerve divides into : • Anterior branch • Posterior branch • At this level it is located lateral and posterior to the femoral artery

• Anterior branch: • Motor innervation to sartorius and pectineus muscles • Sensory innervation to skin of anterior and medial thigh Femoral Nerve: Anatomy

• Posterior branch: • Motor innervation to quadriceps muscle • Sensory innervation to medial aspect of the lower leg via saphenous nerve

Femoral Triangle: Anatomy (Boundaries)

• Superiorly – inguinal ligament • Laterally – medial border of sartorius • Medially – medial border of adductor longus • Base of triangle – inguinal ligament • Apex - medial border of sartorius crosses the medial border of adductor longus • Roof – fascia lata and cribiform fascia • Floor (lateral to medial): • Iliopsoas, Pectineus, Adductor longus Femoral Triangle: Contents

Lateral to medial - NAVY • Femoral nerve • Femoral artery • Femoral vein including great saphenous vein

• Femoral artery, vein, lymphatics and femoral canal are INSIDE the femoral sheath • Femoral nerve and lateral cutaneous nerve lie OUTSIDE the femoral sheath

Femoral Nerve Block

Patient Position • Supine, leg extended

Landmark • Identify anterior superior iliac spine and pubic symphysis • Draw a line between them = indicates inguinal ligament • Palpate femoral artery Femoral Nerve Block

Technique

• Needle is inserted 1-1.5cm lateral to artery and 1-2cm below inguinal ligament

• Needle directed cephalad at 30° to 45° angle to skin, at a depth of 3-4cm

• A brisk “patellar snap” with the current at or< 0.5 mA indicates successful localisation of needle near the femoral nerve

Femoral Nerve Block: Ultrasound

Landmark • Palpate femoral pulse = useful landmark

Femoral Nerve Block: Ultrasound

Landmark • Palpate femoral pulse = useful landmark • Femoral nerve typically visualised at a depth of 2-4cm

Femoral Nerve Block: Ultrasound

October 2004 a) What are the indications for a popliteal fossa block? (10%) b) List the nerves that are affected and describe their cutaneous innervation. (35%) c) What responses would you get on stimulating these nerves? (25%) d) Briefly describe one technique for performing this block. (30%) a) What are the indications for a popliteal fossa block? (10%)

Indications • Surgical procedures below the knee • Foot/ankle Surgery • Short saphenous vein stripping • Corrective foot surgery • Foot debridement • Achilles tendon repair • Sural nerve biopsy

Popliteal Fossa: Anatomy

Boundaries

• Roof – skin and fascia • Medially – tendon of semimembranous and medial head of gastrocnemius • Laterally – tendon of biceps femoris and lateral head of gastrocnemius

• Site where sciatic nerve divides into: • Tibial Nerve • Common peroneal nerve • Division occurs 4-7cm proximal to crease b) List the nerves that are affected and describe their cutaneous innervation. (35%)

Sciatic Nerve (L4-S3) • Supplies all cutaneous innervation except areas supplied by saphenous nerve L2– 4 (branch of the femoral nerve) b) List the nerves that are affected and describe their cutaneous innervation. (35%)

Tibial Nerve (L4-S3) • Largest of 2 divisions • Gives off terminal branches: • Medial and Lateral Plantar Nerves • Supplies anterior and medial parts of the sole of foot • Posterior Tibial nerve calcaneal branch • Supplies the heel b) List the nerves that are affected and describe their cutaneous innervation. (35%)

Common Peroneal Nerve (L4-S2) • Gives off terminal branches • Superficial Peroneal Branch • Supplies dorsum of foot • Deep Peroneal Branch • Supplies area between first and second toes b) List the nerves that are affected and describe their cutaneous innervation. (35%)

Sural Nerve • Formed from branches of tibial and common peroneal nerve • Supplies: • Lateral and posterior third of leg • Lateral aspect of foot and heel and lateral ankle c) What responses would you get on stimulating these nerves? (25%)

• Visible or palpable twitches of the foot or toes at 0.2-0.5 mA current

Common peroneal nerve stimulation • Dorsiflexion and eversion

Tibial nerve stimulation • Plantar flexion and inversion d) Briefly describe one technique for performing this block. (30%)

Patient Positioning • Supine and flex knees to 30° • Lateral decubitus • Prone - allowing foot to extend beyond the bed

Landmark • Identify popliteal crease – Line 1 • Palpate the tendon of biceps femoris muscle (laterally) – Line 2 • Palpate the tendons of semitendinosus and semimembranosus (medially) – Line 3 d) Briefly describe one technique for performing this block. (30%)

Landmark • Needle insertion point marked at 7 cm above popliteal fossa crease at midpoint between the two tendons d) Briefly describe one technique for performing this block. (30%)

Technique • Stand at patients side • Nerve stimulator should be initially set to deliver 1.5 mA current • Insert a 22 G, 100 mm insulated needle posteriorly 25–30° and slightly caudad • Needle is passed through bicep femoris to enter the popliteal fossa • The nerves are located by identifying the responses • Common peroneal nerve - Dorsiflexion and eversion • Tibial nerve - Plantar flexion and inversion • After initial stimulation is obtained, the current is gradually decreased until twitches are still seen or felt at 0.2 to 0.5 mA • This typically occurs at a depth of 3 to 5 cm • 10 - 20ml of LA is injected for each nerve September 2014 a) List five nerves that can be blocked at ankle level for foot surgery? (5 marks) b) For each of these nerves, describe the sensory distribution within the foot. (5 marks) c) Give the anatomical landmarks for an ankle block which aid correct placement of local anaesthesia for each nerve. (5 marks) d) What are the advantages and disadvantages of an ankle block? (5 marks)

Pass Rate 65.9%

“Common clinical subjects tend to score well in the SAQ paper and discriminate between strong and weak candidates as was the case for this question.” “Weak candidates had poor anatomical knowledge or failed to list the advantages of this specific block, giving instead the features common to any local anaesthetic technique.” “Poor candidates tended to describe features of blocks at the popliteal level, perhaps due to failing to read the question thoroughly as ankle level was highlighted. “ ”The importance of candidates retaining knowledge of the basic sciences has been highlighted before”

a) List five nerves that can be blocked at ankle level for foot surgery? (5 marks)

• Sural nerve (L5-S2) • Deep peroneal nerve (L4-S2) • Superficial peroneal nerve (L4-S2) • Saphenous nerve (L3-4) • Tibial nerve (L5-S3)

b) For each of these nerves, describe the sensory distribution within the foot. (5 marks)

Posterior Tibial Nerve (L5-S3) • Branch of the sciatic nerve • Lies posterior to the posterior tibial artery • Supplies the anterior and medial aspect of sole of foot

Sural Nerve (L4-S2) • Branch of the tibial nerve • Accompanies short saphenous vein behind lateral malleolus • Supplies the 5th toe, posterior aspect of sole, back of lower leg and lateral border of foot

b) For each of these nerves, describe the sensory distribution within the foot. (5 marks)

Superficial Peroneal Nerve (L4-S2) • Branch of the common peroneal nerve • Supplies the dorsum of the foot

Deep Peroneal Nerve (L4-S2) • Branch of the common peroneal nerve • Supplies the area between the 1st and 2nd toe

Saphenous Nerve (L3-4) • Branch of the femoral nerve • Supplies the medial side of the ankle joint

c) Give the anatomical landmarks for an ankle block which aid correct placement of local anaesthesia for each nerve. (5 marks)

Deep Peroneal Nerve • Located immediately lateral to tendon of extensor hallucis longus muscle between extensor hallucis longus and the extensor digitorum longus • Pulse of dorsalis pedis artery is felt • The nerve is positioned immediately lateral to artery

c) Give the anatomical landmarks for an ankle block which aid correct placement of local anaesthesia for each nerve. (5 marks)

Posterior Tibial Nerve • Located just behind and distal to medial malleolus • Pulse of posterior tibial artery is felt • The nerve is just posterior to the artery

c) Give the anatomical landmarks for an ankle block which aid correct placement of local anaesthesia for each nerve. (5 marks)

Superficial Peroneal Nerve Located in subcutaneous tissue along a circular line at the level of the lateral malleolus and extending from anterior to posterior

c) Give the anatomical landmarks for an ankle block which aid correct placement of local anaesthesia for each nerve. (5 marks)

Sural Nerve Saphenous Nerve Located in subcutaneous tissue Located in subcutaneous tissue below the fascia behind the just above the medial lateral malleolus malleolus

d) What are the advantages and disadvantages of an ankle block? (5 marks)

Advantages Disadvantages

• Generally well tolerated • Multiple injections required – can • Low risk of systemic LA toxicity be uncomfortable for patient • Low risk of neurological damage • Risk of vascular injection / injury • Facilitates variety of surgical • Potential failure of block / procedures inadequate block • Avoidance of GA, esp in high risk pts • Time consuming • Post-operative analgesia, allowing • Sedation maybe required earlier mobilisation & facilitating • Unable to use a proximal tourniquet physiotherapy for extended periods (thigh/calf) • Avoids complications associated with neuraxial blockade • Avoids use of opioids and their subsequent side effects • Provides intra-operative cardiovascular stability

March 2013 a) Which specific nerves must be blocked to achieve effective local anaesthesia for shoulder surgery? (30%) b) What are the possible neurological complications of an interscalene block? (30%) c) Outline the measures available to reduce all types of neurological damage during shoulder surgery? (40%)

Pass Rate 69.2%

“This question was answered well.” “If an open question is asked on the possible neurological complications of a block then this will include damage to both the peripheral and central nervous system. Some candidates focused on the peripheral nerves only.” “The answer to part c) required an account of both anaesthetic and surgical factors that would reduce neurological damage. This included “avoiding interscalene block” in the first place.” “The question was a very good discriminator. “

April 2009

An adult patient is scheduled for shoulder surgery under an interscalene brachial plexus block. a) Outline the possible unwanted neurological sequelae that may occur with interscalene block and their associated symptoms & signs? (60%) b) What steps may be taken while performing the block to reduce the incidence of these problems? (40%)

Brachial Plexus: Anatomy

Interscalene Block: Indications

• Shoulder surgery • Surgery on clavicle • Upper arm surgery • Reduction of dislocated shoulder • Analgesia for distal structures in the upper limb

Interscalene Block: Anatomy

Interscalene Block: Landmark Technique

• Modified Winnie’s technique

Patient Position • Patient lies supine - head turned slightly away from side to the blocked

Landmark • White arrow: Clavicle • Red arrow: Posterior border of SCM • Blue arrow: External jugular vein Interscalene Block: Landmark Technique

Landmark • Palpate interscalene groove between scalenous anterior and medius • Infiltrate skin with LA • 5cm 50mm short bevelled block needle attached to PNS • Insert needle at 30° aiming for contralateral elbow • Directed in the planes caudally, medially and posteriorly to the transverse processes of C6 • Look for stimulation of deltoid or biceps muscle

Interscalene Block: Ultrasound Technique

Ultrasound Probe • Linear probe, Frequency 10-15 MHz, Depth setting 2-4 cm

a) Which specific nerves must be blocked to achieve effective local anaesthesia for shoulder surgery? (30%)

• Shoulder area innervated by nerves of both cervical and brachial plexuses

Superficial cervical plexus (C3-4): • Supplies skin above clavicle, shoulder tip, and first two intercostal spaces anteriorly

a) Which specific nerves must be blocked to achieve effective local anaesthesia for shoulder surgery? (30%)

Brachial plexus: • Motor supply C5-7

a) Which specific nerves must be blocked to achieve effective local anaesthesia for shoulder surgery? (30%)

Brachial plexus: • Supplies skin over deltoid muscle through upper lateral cutaneous branch of the axillary nerve • Supplies medial side of arm and axilla through medial cutaneous nerve of the arm and the intercostobrachial nerve (T2)

a) Which specific nerves must be blocked to achieve effective local anaesthesia for shoulder surgery? (30%)

• Acromioclavicular joint, capsule and glenohumeral joint: supplied by the suprascapular nerve • The inferior aspect of the capsule and glenohumeral joint: supplied by axillary nerve

a) Outline the possible unwanted neurological sequelae that may occur with interscalene block and their associated symptoms & signs? (60%)

Neurological Sequelae Symptoms & Signs

Inadvertent epidural or subarachnoid • Total Spinal injection • Anxiety/nausea, arm or hand dysaesthesia or paralysis, cranial nerve involvement, LOC with profound cardiorespiratory compromise

Phrenic nerve block • Paralysis of the hemi-diaphragm leading to reduced FVC/FEV1 • May have considerable impact on patients who are obese or with underlying respiratory problems

a) Outline the possible unwanted neurological sequelae that may occur with interscalene block and their associated symptoms & signs? (60%)

Neurological Sequelae Symptoms & Signs

Recurrent laryngeal nerve block • Hoarseness of voice secondary to unilateral vocal cord palsy

Vagal nerve block • Hoarseness of voice • Reduced cough reflex

Cervical sympathetic blockade • Horner’s syndrome

Nerve injury • Paresthesia (permanent/temporary)

b) What steps may be taken while performing the block to reduce the incidence of these problems? (30%)

• Full monitoring as per AAGBI • Education and sound understanding of anatomy • Only perform unilateral blocks, STOP BEFORE YOU BLOCK • Awake patient so patient can report pain or paresthesia on injection • Do not inject against resistance • USS guidance • USS guidance plus nerve stimulator • Experienced practitioner • A practitioner who is experienced in one or 2 upper limb blocks • Repeated aspiration during injection to ensure needle tip has not moved into a vascular space

c) Outline the measures available to reduce all types of neurological damage during shoulder surgery? (40%)

Anaesthetic Factors • Thorough preoperative history and examination • Identify conditions that predispose to nerve injury and existing neurological dysfunction • Avoidance of block • Avoid intraoperative hypotension, hypothermia, and dehydration • Careful positioning of patient • Protective padding and padded arm boards • Avoidance of contact with hard surfaces or supports that may apply direct pressure to susceptible peripheral nerves • Arm abduction limited to < 900 in supine position to prevent brachial plexus lesions • Protection of ulnar and median nerves: padding should be mandatory and forearm kept in supine or neutral position • Flexion/extension of the elbow should be < 900

c) Outline the measures available to reduce all types of neurological damage during shoulder surgery? (40%)

Surgical Factors • Head and neck should be secure and care should be taken throughout the pro-cedure to ensure that excessive stretching of the brachial plexus does not occur as a result of the excessive surgical traction • Avoidance of direct nerve injury through surgical laceration and nerve contusion • Avoidance of traction on nerve particularly with arthroscopic surgery • Avoidance of excess arm manipulation

November 1996

• Describe how you would carry out an axillary brachial plexus block

Axillary Block: Anatomy Axillary Block: Landmark Technique

Patient Position • Supine position with head turned away to the opposite side • Arm abducted to 90 and the hand under the head or externally rotated

Landmark • Palpate axillary artery in axilla as high as possible at the lateral border of pectoralis major Axillary Block: Landmark Technique

Landmark • Needle is inserted at 45° just above the axillary artery pulsation • Inject LA when a click in the perivascular sheath is felt or muscle stimulation is apparent Radial Nerve = Wrist and finger extension Ulnar Nerve = Thumb adduction, and flexion of 5th finger Median Nerve = Flexion of fingers Musculocutaneous Nerve = Elbow flexion

Axillary Block: Ultrasound Technique

Ultrasound Probe • Linear probe, Frequency 10-15 MHz, Depth setting 2-4 cm

September 2012 a) Describe the innervation of the anterior abdominal wall. (20%) b) In which types of surgery would a transversus abdominus plane (TAP) block be used and what are the potential benefits? (25%) c) Outline how you would perform a TAP block. (40%) d) What are the specific complications of a TAP block? (15%)

Pass Rate 67.4%

“The question was relevant and topical.” “Many candidates had poor knowledge of the innervation of the anterior abdominal wall.” “Overall was answered well.”

a) Describe the innervation of the anterior abdominal wall. (20%)

• Innervation of anterolateral abdominal wall arises from anterior rami of spinal nerves T7 to L1 • Intercostal nerves: T7-T11 • Subcostal nerves: T12 • Iliohypogastric and ilioinguinal: L1

a) Describe the innervation of the anterior abdominal wall. (20%)

• Anterior divisions of T7-T11 continue from the intercostal space • Enter abdominal wall between internal oblique and transversus abdominis muscles until they reach the rectus abdominis • Here they perforate and supply the skin of the front of the abdomen via anterior cutaneous branches

a) Describe the innervation of the anterior abdominal wall. (20%)

• Midway along their course, they pierce external oblique muscle giving off lateral cutaneous branch

• This divides into: • Anterior branch – supplies external oblique • Posterior branch – supplies latissmus dorsi

a) Describe the innervation of the anterior abdominal wall. (20%)

• Anterior branch of T12 communicates with iliohypogastric nerve

• Gives off a branch to pyramidalis muscle

• Lateral cutaneous branch perforates internal and external oblique muscles • Descends over the iliac crest • Supplies sensation to front part of gluteal region

a) Describe the innervation of the anterior abdominal wall. (20%)

• Iliohypogastric and ilioinguinal nerve form part of the lumbar plexus

• Enter the transverse abdominis plane near to the iliac crest

• Iliohypogastric nerve (L1) divides into lateral and anterior cutaneous branches • Lateral cutaneous branch supplies skin over gluteal region • Anterior cutaneous branch supplies skin over hypogastric region

• Ilioinguinal nerve (L1) travels within the inguinal canal • Supplies the upper and medial part of the thigh and part of the skin covering the genitalia

b) In which types of surgery would a transversus abdominus plane (TAP) block be used and what are the potential benefits? (25%)

Uses Potential Benefits

Upper/Lower abdominal surgery • Role in decreasing analgesia • Open inguinal/umbilical hernia requirements • Open appendicectomy • Used where epidural is • Midline Laparotomy contraindicated • Open cholecystectomy • Used in ambulatory surgery to improve the quality of analgesia Gynaecological/Obstetric surgery • Reduce postoperative opioid • Hysterectomy via pfannenstiel requirements incision • LSCS via pfannenstiel incision

Urology • Prostatectomy • Renal transplant • Nephrectomy

c) Outline how you would perform a TAP block. (40%)

Patient Position • Supine

Landmark • TAP found in triangle of petit • Posterior – latissamus dorsi • Anterior – external oblique • Inferior – iliac crest

• Triangle of petit identified on lateral aspect of abdominal wall, mid axillary point

c) Outline how you would perform a TAP block. (40%)

Blind Technique • 50-100mm blunt needle inserted perpendicular to skin within triangle of petit • Advanced through the skin and 2 distinct “pops” are felt as needle traverses the external oblique and internal oblique muscles • = transvusus abdominus plane • After negative aspiration, inject 20mL of LA

c) Outline how you would perform a TAP block. (40%)

Ultrasound Technique • High frequency linear probe (10-5 MHz) • Patient in supine position • Probe placed transverse to abdominal wall between costal margin and iliac crest

c) Outline how you would perform a TAP block. (40%)

d) What are the specific complications of a TAP block? (15%)

Complications • Intraperitoneal injection/haematoma • Bowel hematoma • Transient femoral nerve palsy • Intrahepatic injection • Local anaesthetic toxicity - due to large volumes required to perform block especially if bilateral

April 2008 a) Describe the anatomy of the thoracic paravertebral space. (35%) b) What are the indications for paravertebral nerve blockade? (25%) c) List the complications of a paravertebral nerve block. (30%)

a) Describe the anatomy of the thoracic paravertebral space. (35%)

• Wedge shaped potential space that Space • Extends from T1 to T12 • Found on each side lateral to the bony vertebral column a) Describe the anatomy of the thoracic paravertebral space. (35%)

BOUNDARIES

Anterolateral (Posterior to anterior) • Parietal pleura • Pleural space • Visceral pleura • Lung parenchyma

Medial • Vertebral body • Vertebral disc • Vertebral foramina a) Describe the anatomy of the thoracic paravertebral space. (35%)

BOUNDARIES

Posterior • Transverse process • Costo-transverse ligament

Superior • Head of adjacent rib

Laterally • Posterior intercostal membrane • Intercostal space a) Describe the anatomy of the thoracic paravertebral space. (35%)

CONTENTS

• Spinal nerve roots • Sympathetic chain • White and grey communicates • Lymph nodes • Fat • Intercostal vessels

b) What are the indications for paravertebral nerve blockade? (25%)

Unilateral Surgical Procedure in Relief of Acute Pain Thoraco-abdominal Region • Fractured ribs • Breast surgery • Liver capsule pain (trauma/ruptured • Thoracic surgery cysts) • Cholecystectomy • Renal surgery • Appendicectomy • Inguinal hernia repair Relief of Chronic Pain Sympathetic Blockade

• Neuropathic chest or abdominal pain • Therapeutic control of hyperhydrosis (post-surgical or post-herpetic) • SVT • Complex regional pain syndrome • Refractory angina pectoris • Relief of cancer pain

c) List the complications of a paravertebral nerve block. (30%)

General Complications Specific Complications

• Hypotension (4.6%) • Nerve trauma • Vascular puncture (3.8%) • Pleural tap with seeding of malignant • Pleural puncture (1.1%) cells • Pneumothorax (0.5%) • Intra-pleural block • Lumbar spread with quadriceps weakness • Epidural spread • Bilateral spread of local anaesthetic • Ipsilateral Horner’s syndrome

Contraindications to Block

Absolute Relative

• Patient refusal • Severe coagulopathy • local sepsis (cutaneous or • Severe respiratory disease (where intrathoracic) the patient depends on intercostal • Tumours in the paravertebral space muscle function for ventilation) at the level of injection • Ipsilateral diaphragmatic paresis • Allergy to local anaesthetic drugs

Paravertebral Block: Technique

Patient Position • Sitting • Lateral decubitus

Landmarks • Spinal processes main landmark • Represent midline • C7 – T7

Paravertebral Block: Technique

May 2007 a) Describe the anatomy of an intercostal nerve. (25%) b) How does this influence your technique of intercostal nerve blockade for a fractured rib? (35%) c) List the complications that may arise and explain the anatomical reasons for these complications. (30%)