Sedation & Local Anaesthesia

1. HKCEM College Tutorial Sedation & Local Anaesthesia Author Dr. Jenny Lam Revised by Dr. Chang Wai Yin, James Oct 2013

2. Scope of Sedation Use in AED: • Brief and minor procedures • Severely agitated patients (look for the cause of the problem, such as hypoxia, hypoglycaemia, or a full bladder!) • Procedure sedation • A technique of administering sedatives or dissociative agent with or without analgesics • to allow patient undergo unpleasant procedure • While cardio-respiratory function is maintained

3. Sedative Used in A&E • Most Common • Benzodiazepines • Diazepam • Choral Hydrate • Nitrous Oxide (N2O) • Less Common • Ketamine • Etomidate • Propofol • Do you know the common route and dosage (adult and paed)? • Do you know the onset, duration of these drugs?

4. Procedural Sedation • Common Use • Close Reduction in joint dislocation/simple fractures • Synchronized Cardioversion • Usually used together with analgesia • Morphine • Pethdine • Fentanyl • Do you know the antidote?

5. Case 1 • M/47 • Known OSAS • Slip and fell and landed on outstretched left hand • Left shoulder pain with decreased movement • Exam: squaring deformity left shoulder

6. Dx? • How would you manage? • XR to confirm • **Preparation** for conscious sedation • Oxygen, suction, BVM, monitors, IV access, Drugs (include reversal/antidote)

7. Procedural Sedation • You confirmed anterior shoulder dislocation and decided to undergo close reduction • How are you going to perform the procedure? • What are your choice of medication?

8. You have chosen Midazolam as sedative and Pethidine as analgesia. • After administration, how will you assess the level of sedation?

9. Ramsay Scale

10. What and how will you monitor during the procedure? • Vitals • RR • Pulse oximeter

11. Despite several trial and different method, you still fail to reduce the dislocation. • You are informed the O2 saturation of the patient drop to 89% • What will you do?

12. Flumazenil • Flumazenil (Anexate) : used to treat benzodiazepine overdose or neonatal sedation • may be useful in establishing a Dx in patients with coma of unknown cause • Onset within mins and with short T1/2h • Dosage: 0.2mg iv initially, repeated every 1min • Max: 3mg/hr

13. Points to Remember • should be performed in a room with resuscitation equipment. • Adequate assessment pre-sedation and documentation • drug should be titrated slowly • An opioid given to provide adequate analgesia • Verbal contact with patient maintained airway

14. Points to Remember • If verbal contact lost , simple sedation has progressed to general anaesthesia, airway control may be compromised! • After the procedure, patient should under close supervision until full recovery assured • Hong Kong Academy of Medicine Guidelines on Procedural Sedation http://www.hkam.org.hk/publications/Guidelines_on_Procedural_Sedation.pdf

15. Local Anaesthesia

16. Local Anaesthesia • Pain control, with minimal discomfort or danger to the patient • Facilitate simple surgical procedure • can also be used merely for pain relief • e.g. femoral nerve block for a mid-shaft fracture of the femur

17. Action of local anaesthetic drugs Two types of LA: • Esters: Cocaine, Amethocaine • Amides: Lignocaine (Xylocaine), Bupivacaine (Marcaine), Prilocaine Action: Na-channel blocker on axonal membranes inhibition of nerve impulse conduction

18. Use of Local Anesthetics • Numerous • Suture • I&D • FB removal (skin, eye, ear…) • Nerve block as Regional Anaesthesia

19. Types of Regional Anaesthesia • Local infiltration • Field Block • Nerve/Regional Block • Intravenous regional anaesthesia (IVRA: Bier’s Block ) • Topical anaesthesia • Spinal & epidural anaesthesia

20. Local infiltration of the skin • Indications: 1. Suturing lacerations 2. Minor surgical procedures e.g. excision of cyst 3. Supplemementing a nerve block 4. Cleaning and debriding wounds • Contraindication : Allergy, severe bleeding disorder, unco-operative/violent patient, patient’s choice

21. Dosage: up to 20 ml of 1% lignocaine or 40 ml of 0.5% lignocaine with or without adrenaline. Larger doses may be used with adrenaline. • Technique: inject LA around the area to be treated, as to block the distal nerve endings and filaments there. • Onset: 2-3 mins ; Duration: up to 40 mins

22. Case 2 • M/50 • DM • Lorry driver, RTA, head-on collision with front bus on highway • No LOC

23. At A&E • L thigh obvious deformity • In severe pain • BP/P 159/72, pulse 104/min • GCS 15/15 • Chest/abdomin exam unremarkable • FAST -ve • Anything to help for pain relief?

24. Hare Splintage under Femoral nerve block • How to perform Femoral nerve block? • Traditional method vs Ultrasound method

25. Procedure done under aseptic technique without use of ultrasound • 7 min later • Complained of dizziness and palpitation • BP 101/63, pulse 124/min

26. Differential Diagnosis ?

27. 5 min later • Further deterioation with decrease sensorium, confused • BP 91/45, pulse 51/min • H’cue 11.2 • H’stix 5.4 What is the mostly diagnosis?

28. Lignocaine toxicity!! What are the symptoms? -local: allergy -CNS: lightheadness, metallic taste, circumoral paraesthesia, tinnitus, seizure, coma -CVS: hyper/hypotension, bradycardia -Methemoglobinemia

29. What is the maximum dose? • 5mg/kg (not exceed 300mg) if no adrenaline • 7mg/kg (not exceed 500mg) with adrenaline • Why overdose? • Inadvertently IV injection • Injected too much • Rapidly absorbed

30. How would you manage?

31. Management • Support ABC • Do you know any antidote or special treatment? • Intralipid emulsion infusion 20% • 1.5ml/kg over 1min followed by 0.25ml/kg/min • Repeat bolus Q5min for persistent cardiovascular collapse • Double infusion rate if BP returns but remain low • Continue infusion for a minimum of 30min • Contraindication: lipid metabolism disorder, egg allergy

32. Other Common Nerve Block

33. Digital nerve block • Indications : simple operations on the two-thirds of fingers or toes • Special contraindication: None • Anatomy: a dorsal and palmar nerve run along each side of the digit • Dosage: 2-5 ml of 1% plain lignocaine • Onset: 2-5 mins ; Duration: 45 mins - 1 hr

34. Digital nerve block • Technique

35. Cautions! • Never use LA with adrenaline around end arteries e.g. digits, ear, nose or penis • Avoid injecting LA directly along the wound margin, this distorts wound edges for skin apposition. It may introduce infection. • Ensure the maximum dose for LA & adrenaline is not exceeded

36. Complications of LA • Allergic reactions • Local infection • Haematoma and bruising • Needle breakage • Nerve damage • Ischaemia and necrosis • Reactions to vasoconstrictors • Methaemoglobinaemia

37. The End