Local & regional anaesthesia Mr Matt Baker

Aims Topical anaesthesia Lignocaine vs. bupivicaine Digital nerve block Wrist blocks Haematoma block Bier’s block Femoral nerve block Ankle blocks

Topical anaesthesia LAT gel Instillagel Soaked dental roll EMLA/Ametop – not for open wounds

Local anaesthetics Lignocaine Lignocaine with adrenaline (1:200,000) Dose: 4mg/kg Onset: rapid Duration: 30-60 mins Lignocaine with adrenaline (1:200,000) Dose: 7mg/kg Duration: 90 mins Bupivicaine Dose: 2mg/kg Onset: 10-15 mins Duration: 3-8 hrs Bupivicaine: Max dose if 75kg = 150mg = 30ml of 0.5%

Mechanism of action of LA LA decrease sodium influx Reduces rate of rise and amplitude of depolarisation Eventually unable to achieve threshold to fire action potential Therefore, no impulse transmitted as blocked conduction

LA toxicity Side effects: Management of toxicity: Neurological Cardiac Oxygen, i.v. access, ECG monitoring, full obs BDZ if seizure Fluid bolus if hypotensive Intralipid 20% 1.5ml/kg i.v. over 1 min then infusion of 0.25ml/kg/min Occur due to overdosage of lignocaine or inadvertent intravascular injection. Can occur 10-25mins post injection. Neuro: numbness mouth & tongue, slurred speech, lightheadedness, tinnitus, confusion, drowsiness, convulsions & coma. Cardiac: tachycardia & hypertension then hypotension with bradycardia & heart block. Occ ventric arrhthymias and arrest.

1. Digital nerve blocks Use 1-2ml lignocaine on either side of finger Inject from dorsal side If big toe or proximal phalanx, give extra injection of LA across dorsum of digit to cover dorsal digital nerves Single injection technique +/- adrenaline Some evidence that using lignocaine + adrenaline in digital nerve blocks does not cause necrosis and ischaemia. Digital nerves derived from medial and ulnar nerves and divide into paired palmar branches. Dorsal digital nerves derived from radial and ulnar nerves and supply dorsal aspect of prox phalanx.

2. Wrist blocks Median nerve: Ulnar nerve: Radial nerve: Radial half palm Thumb, index & middle fingers Radial half of ring finger Ulnar nerve: Ulnar border hand Little finger Ulnar half ring finder Radial nerve: Dorsum of radial side hand

2. Wrist blocks Median nerve: Between palmaris longus & flexor carpi radialis Ask patient to flex wrist and oppose thumb & little finger Inject between tendons at proximal wrist crease 5ml 1% lignocaine 1ml subcut. to block palmar cutaneous branch Use approx 5ml 1% lignocaine -Palmar cutaneous branch supplies sensation to skin of thenar eminence and palm -If no palmaris longus, then inject ulnar side of FCR

Median Nerve

Ulnar nerve Palmar branch: Dorsal branch: Inject: runs with ulnar artery Supplies hypothenar eminence & palm Dorsal branch: Passes under FCU Supplies ulnar border of dorsum of hand Inject: Between artery & FCU Plus around ulnar border wrist Inject between artery and FCU at level of ulnar styloid process, approx 5ml 1% lignocaine

Radial nerve Radial nerve lies subcutaneously on dorsum of wrist & divides into branches Infiltrate 5ml 1% lignocaine subcutaneously around radial side of wrist from FCR to radio-ulnar joint

3. Haematoma block 10ml 1% lignocaine into haematoma from dorsal aspect of wrist Occ. need few ml’s around ulnar styloid too No monitoring required Risks: Infection LA toxicity No use once > 24hrs old as haematoma organised

Bier’s block 40ml 0.5% prilocaine (30ml if elderly or frail) Full monitoring in resus. i.v. access both arms Check radial pulse then elevate arm to exsanguinate Inflate tourniquet to at least 100mmHg above SBP (record time) Inject prilocaine into isolated limb Test after 5 mins Manipulate, remove cannula and apply POP Keep inflated for at least 20 mins then deflate slowly & record time. Watch for signs of toxicity Contraindications: Severe hypertension, severe PVD, sickle cell, Raynauds, MetHb, procedures required in both arms

Haematoma vs. Biers block Personal choice Best Bets: Biers block better in terms of pain score & need for remanipulation Variable findings re. Xray results Less risk of side effects with haematoma block and only need one doctor present

4. Femoral nerve block Femoral nerve supplies: Hip Knee Muscles in anterior compartment of thigh Skin of medial & anterior thigh Skin of medial aspect of leg below knee Skin below knee = saphenous nerve

Femoral nerve block Insert needle approx 0.5 – 1cm lateral to femoral artery perpendicular to skin Stand on opposite side Use lignocaine plus bupivicaine or bupivicaine alone Stand to left side if right femoral nerve (if right hand dominant) Compress artery if puncture it

5. Ankle blocks Five nerves: Saphenous n. Superficial peroneal n. Deep peroneal n. Sural n. Tibial n. Use lignocaine or bupivicaine Approx 5ml required Saphenous n = medial side ankle Common peroneal nerve – from tibial nerve, divides just below head of fibula. Superficial peroneal n. = front ankle & dorsum foot Deep peroneal n. = 1st dorsal web space Sural n. = heel & lateral border of foot Tibial n. = anterior half of sole

(i) Saphenous nerve: Subcut. infiltration around great saphenous vein, anterior & just above medial malleolus Aspirate to ensure not intravascular injection Supplies: medial side of ankle

(ii) Superficial peroneal nerve: Subcut. infiltration above ankle joint from anterior border of tibia to lateral malleolus Supplies: front of ankle and dorsum of foot

(iii) Sural nerve Emerges from between heads of gastrocnemius on lateral side of Achilles then descends behind lateral malleolus Infiltrate from lateral border of Achilles tendon towards to the lateral malleolus Heel and lateral border of foot

(iv) Deep peroneal nerve: Located between EHL & EDL Nerve is lateral to dorsalis pedis pulse Insert needle between tendons ‘til touch bone then infiltrate as withdraw needle Supplies: 1st dorsal web space

(v) Tibial nerve: Palpate posterior tibial artery Insert needle medial to Achilles tendon, lateral to artery, level with upper border of malleolus Supplies: anterior half of sole

Summary Various blocks that are simple to do and effective Always watch for signs of LA toxicity Hard to remember them all so look them up and try them out!

Any questions?