Peripheral Nerve Blocks Diane Williamson Emergency Medicine Consultant CUHFT

Peripheral Nerve Blocks Preparation, complications, agents Digital nerve block Wrist block Fascia iliac block Other nerve blocks – ankle and face Local anaesthetic toxicity

Right Block Right Patient http://www.frca.co.uk/Documents/134%20Peripheral%20nerve%20blocks,%20getting%20started.pdf Is there a block that will benefit your patient? Do you know the anatomy and technique? Have you obtained informed consent? Have you established? IV access Monitoring – ECG, BP SpO2

Potential Complications Block failure Intravascular injection Local anaesthetic toxicity – know the signs/symptoms Nerve damage Injury secondary to numbness or weakness Infection

Preparation Infection control – sterile gloves, drape, antiseptic cleaning solution (2% chlorhexidine) Equipment Local anaesthetic Syringe Needle e.g. 23G (blue), Blunt bevelled, dental USS Nerve stimulator

Local Anaesthetic Agents http://www.frca.co.uk/article.aspx?articleid=100816 Lidocaine Onset 5-10 minutes Duration 1-2 hours Maximum dose 3mg/kg (with epinephrine 7mg/kg) Prilocaine Maximum dose 6mg/kg Bupivocaine and L-bupivociane (chirocaine) Onset 10-15 minutes Duration 3-12 hours Maximum dose 2mg/kg

Safe Injection Know the anatomy – near, not in the nerve Aspirate first Inject incrementally (5ml at a time) Expect: negative aspiration, painless, easy to inject, spread of LA if using USS If in doubt - STOP

With or without adrenaline? Adrenaline is a vasoconstrictor – think first

Contraindications Patient refusal Anticoagulation Inflammation or infection over injection site Allergy to local anaesthetics

Digital Nerve Blocks Web-space block Trans-thecal block https://www.aagbi.org/sites/default/files/275%20Wrist%20Block%20-%20Landmark%20Technique.pdf Trans-thecal block

Anatomy

Equipment Sterile field Skin prep antiseptic (2% chlorhexidine) 23G (blue) needle 5ml syringe Local anaesthetic (e.g. 1% lidocaine)

Web-space block Place hand palm down on sterile field Hold syringe perpendicular to digit Insert needle into web space 1st distal to MP joint Aspirate and inject slowly into dorsal aspect Advance needle to volar aspect of web space Aspirate and inject

Transthecal block Also called flexor tendon sheath block Place hand palm up on sterile field Palpate flexor tendon sheath at distal palmar crease Insert needle at 45deg just distal to crease Aspirate and inject slowly

Anatomy

Wrist Block Anatomy 6 nerves supply the wrist/hand Median Ulnar https://www.aagbi.org/sites/default/files/275%20Wrist%20Block%20-%20Landmark%20Technique.pdf Anatomy 6 nerves supply the wrist/hand Median Ulnar Dorsal branch of ulnar nerve Radial Posterior interosseous Anterior interosseous

Equipment 15ml local anaesthetic (e.g. 1% lidocaine or combined with 0.5% bupivocaine) 10ml syringe 23G (blue) needle Chlorhexidine 2% skin antiseptic

Radial Nerve “Field block” Inject subcutaneously, 3cm proximal to radial styloid Aim medially then extend laterally Up to 5ml local anaesthetic

Median Nerve Insert 2.5cm proximal to wrist crease between tendons of palmaris longus and flexor carpe radialis (proximal to carpal tunnel) Pierce deep fascia (3.5mm) 3-5ml local anaesthetic

Ulnar Nerve Insert needle under the tendon of flexor carpi ulnaris close to ulnar styloid Advance 5-10mm 3-5ml local anaesthetic

Posterior Interosseus Nerve Forearm in pronation Ulnar border of distal radius 3cm proximal to palpable ulnar head Insert to contact radial cortex and inject into periosteum where nerve lies 2ml local anaesthetic

Anterior Interosseus Nerve “walk off” ulnar border of radius after injecting the posterior interosseus nerve Between radius and ulna, feel “click” of passing through interosseous membrane 2ml local anaesthetic

Fascia Iliaca Block http://www.aagbi.org/sites/default/files/193-Fascia-Iliaca-compartment-block.pdf Innervation of medial, anterior and lateral aspects of thigh L2 to 4 Fascia iliaca compartment contains 3 of 4 major nerves to the leg Local anaesthetic reliably reaches the femoral and LFCN only

Indications Specific Contraindication: Perioperative analgesia for patients with fractured neck or shaft of the femur Analgesia for plaster applications in children with femoral fracture Analgesia for lower leg tourniquet pain during awake surgery Specific Contraindication: Previous femoral popliteal bypass graft

Equipment Blunted or short-bevelled needle Skin antiseptic (2% chlorhexidine) 1-2ml 1% lidocaine for skin infiltration 30-40ml bupivocaine (or L-bupivocaine) in the right dose (2mg/kg)

Landmarks Anterior superior iliac spine Pubic tubercle Connecting line divided in thirds Injection point is 1cm caudal to junction of lateral and middle thirds

Procedure Landmark Palpate femoral artery pulse (injection point should be 1-2cm lateral to the pulse) Infiltrate skin with 1% lidocaine Blunt needle – pierce skin at right angle Angle to 60deg – point cranially in sagittal plane Advance through two “pops” Angle to 30deg, advance 2mm Aspirate - if negative, inject 5ml and repeat Anaesthetic should enter freely and without pain Monitor for 30 minutes post-injection

Nerves blocked Femoral and Lateral femoral cutaneous nerve FCN blockade of the obturator nerve unreliable, despite its location within the same anatomical compartment

More Blocks You Should Know Ankle Femoral nerve (next year) Facial Auricular Supra-trochlear Supra-orbital

Ankle http://www.cambridgeorthopaedics.com/cambridgeanaesthetics/advancednerveblocks/ankle%20block.htm

Auricular LON – lesser occipital nerve ATN – auriculotemporal nerve GAN – greater auricular nerve

Supratrochlear and Supraorbital

Infraorbital and Mental

Local Anaesthetic Toxicity Recognition Immediate Management Treatment Follow-up

Intralipid

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