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Regional and Obstetric Anaesthesia

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  1. Regional and Obstetric Anaesthesia Dept of Anaesthesia & Intensive Care The Chinese University of Hong Kong

  2. Main types of regional anaesthesia. • Indications and application of regional anaesthesia. • Contraindications and adverse effects of regional anaesthesia. • Special problems of obstetric patients. • OBJECTIVES:

  3. What are the main types of regional anaesthesia ? • Local Infiltration • Peripheral Nerve blocks • Multiple nerve blocks: • Plexus blocks • IV regional anaesthesia (Bier’s block) • Neuraxial blocks: • Spinal • Epidural • (Caudal)

  4. A 22 yr old medical student went to the beach and requires 4 stitches for a cut from glass on her foot. • A 30 yr old man jammed his hand in a car door and requires debridement of a crushed index finger. • 3. A 69 yr old chronic smoker with severe COAD slipped and fell and requires manipulation of a fractured distal radius. • A 31 yr old woman for Caesarean section with breech & ruptured membranes 1 hr after finishing breakfast. • A 35 yr old term parturient has a sudden persistent decrease in fetal heart rate to 80 bpm. • Case Scenarios:

  5. A 22 yr old medical student went to the beach and requires 4 stitches for a cut from glass on her foot. • A 30 yr old man jammed his hand in a car door and requires debridement of a crushed index finger. • 3. A 69 yr old chronic smoker with severe COAD slipped and fell and requires manipulation of a fractured distal radius. • A 31 yr old woman who is 38 weeks pregnant presents with breech presentation & ruptured membranes 1 hr after finishing breakfast. • A 35 yr old parturient at 39 weeks has a sudden persistent decrease in fetal heart rate to 80 bpm. • Case Scenarios:

  6. Main types of regional anaesthesia • Local Infiltration • Nerve blocks • Multiple nerve blocks: • Plexus block • IV regional anaesthesia (Bier’s block) • Neuraxial blocks: • Spinal • Epidural, caudal

  7. Main types of regional anaesthesia • Local Infiltration • Nerve blocks • Multiple nerve blocks: • Plexus blocks • IV regional anaesthesia (Bier’s block) • Neuraxial blocks: • Spinal • Epidural, caudal

  8. What is local infiltration? • Injection of local anesthetics around the surgical incision to anaesthetize the nerve endings

  9. When NOT to use local infiltration? • Wound involving large surface area that might require a great volume of local anesthetics which can cause toxic effects • Areas where tissue distortion associated with infiltration would impede repair • e.g. plastic repair on the face

  10. What drugs to use? • Local anesthetics +/- adrenalin • e.g. lignocaine • bupivacaine • ropivacaine • mepivacaine

  11. How about cocaine? • NOT COCAINE!! • High systemic toxicity • For topical use only e.g. ENT surgery

  12. Why add adrenalin? • Is added to LA solutions to reduce vascularity of the area by direct vasoconstriction and reduce the systemic uptake of the drug • Can increase duration of the block • Greater margin of safety for systemic toxicity • Reduce surgical bleeding

  13. What are the precautions when using adrenalin containing LA? • Should not be injected in proximity of end-arteries, such as fingers, toes, penis as there is no collateral circulation to supplement the supply if vasoconstriction is severe • Cautious in patients with ischaemic heart disease, peripheral vascular disease

  14. What doses of LA can be used? • Lignocaine • without adrenalin: about 3mg/kg • with adrenalin: about 7mg/kg

  15. Question • A 70 kg gentlemen is admitted to have his large lipoma excised, if the surgeon wants to use 2% lignocaine with adrenalin, what will be the maximum safety volume he can use?

  16. Maximum amount of lignocaine can be used : 70 X 7 = 490 mg • 2 % lignocaine = 2g in 100ml • =2000mg in 100ml • =20mg per ml • Maximum volume= 490/20 • = 24.5 ml

  17. What are the toxic effects of LA? • Perioral numbness • Tinnitus • Muscle twitching • LOC • Convulsion • Coma • Respiratory arrest • CVS arrest

  18. A 22 yr old medical student went to the beach and requires 4 stitches for a cut from glass on her foot. • A 30 yr old man jammed his hand in a car door and requires debridement of a crushed index finger. • 3. A 69 yr old chronic smoker with severe COAD slipped and fell and requires manipulation of a fractured distal radius. • A 31 yr old woman who is 38 weeks pregnant presents with breech presentation & ruptured membranes 1 hr after finishing breakfast. • A 35 yr old parturient at 39 weeks has a sudden persistent decrease in fetal heart rate to 80 bpm. • Case Scenarios:

  19. Main types of regional anaesthesia 1. Local Infiltration 2. Nerve blocks 3. Multiple nerve blocks: • - Plexus blocks 4. IV regional anaesthesia (Bier’s block) 5. Neuraxial blocks: • - Spinal • - Epidural, caudal

  20. Main types of regional anaesthesia 1. Local Infiltration 2. Nerve blocks 3. Multiple nerve blocks: • - Plexus blocks 4. IV regional anaesthesia (Bier’s block) 5. Neuraxial blocks: • - Spinal • - Epidural, caudal

  21. What is a peripheral nerve block? • Injection of local anesthetics close to a peripheral nerve to achieve analgesia

  22. What nerves can be block? • Upper limb: digital nerve block, wrist block • Lower limb: ankle block • Others: intercostal nerve block, penile block

  23. What are the precautions? • Direct peripheral nerve damage • Injuries to the surrounding structures

  24. A 22 yr old medical student went to the beach and requires 4 stitches for a cut from glass on her foot. • A 30 yr old man jammed his hand in a car door and requires debridement of a crushed index finger. • 3. A 69 yr old chronic smoker with severe COAD slipped and fell and requires manipulation of a fractured distal radius. • A 31 yr old woman who is 38 weeks pregnant presents with breech presentation & ruptured membranes 1 hr after finishing breakfast. • A 35 yr old parturient at 39 weeks has a sudden persistent decrease in fetal heart rate to 80 bpm. • Case Scenarios:

  25. Why avoid GA? • GA can further compromise respiratory function by atelectsis, increase V/Q mismatch • Any airway manipulation can precipitate brochospasm

  26. Main types of regional anaesthesia 1. Local Infiltration 2. Nerve blocks 3. Multiple nerve blocks: • - Plexus blocks 4. IV regional anaesthesia (Bier’s block) 5. Neuraxial blocks: • - Spinal • - Epidural, caudal

  27. Main types of regional anaesthesia 1. Local Infiltration 2. Nerve blocks 3. Multiple nerve blocks: • - Plexus blocks 4. IV regional anaesthesia (Bier’s block) 5. Neuraxial blocks: • - Spinal • - Epidural, caudal

  28. How does a plexus block work? • Mechanism: - blocking the plexus by injecting LA which spread within a fascial sheath

  29. What nerve plexus can be blocked? • Typical plexus blocks: • - Brachial, lumbar

  30. What type of surgery is suitable? • Types of surgery: - Useful for limb surgery only

  31. What are the precautions and risks? • Precautions and risks: - Dosages, adjacent structures.

  32. 3. Plexus blocks Example: Brachial plexus block

  33. What are the adverse effects of brachial plexus block?

  34. Brachial Plexus Block Main risks • Local anaesthetic toxicity • Pneumothorax • Phrenic nerve block • Brachial plexus injury

  35. 4. IV Regional Anaesthesia • Bier’s block. • Useful for limb surgery • Method: apply a touniquet over the limb and then inject LA into a IV catheter placed in distal region • Anaesthesia is produced by direct diffusion of LA from vessels into nearby nerves

  36. Intravenous regional anaesthesia • Advantages: simple • reliable • Disadvantages: touniquet discomfort • no post -op pain relief

  37. Precautions • The pressure of the touniquet should be 100mg above the systolic pressure of the patient • Avoid sudden accidental release of touniquet which can cause LA toxicity

  38. A 22 yr old medical student went to the beach and requires 4 stitches for a cut from glass on her foot. • 2. A 13 yr old boy jammed his hand in a car door and requires debridement of a crushed index finger. • 3. A 69 yr old chronic smoker with severe COAD slipped and fell and requires manipulation of a fractured distal radius. • 4. A 31 yr old woman who is 38 weeks pregnant presents with breech presentation & ruptured membranes 1 hr after finishing breakfast. • A 35 yr old parturient at 39 weeks has a sudden persistent decrease in fetal heart rate to 80 bpm. • Case Scenarios:

  39. Types of regional anaesthesia • Local Infiltration • Nerve blocks • Plexus blocks • IV regional anaesthesia (Bier’s block) 5. Neuraxial blocks

  40. 5. Neuraxial block • What are the differences between a spinal and an epidural?

  41. Spinal vs Epidural • Outside dura (no CSF) • Endpoint: “loss of resistance” • Large needle (Tuohy, 16G) • Catheter • Slow, large dose. • use: For surgery and pain relief. • Through dura (CSF) • Endpoint: CSF • Small needle (eg.25 G) • Single shot • Rapid, small dose • use: For surgery.