Epidural analgesia technique

Transcription

1 Epidural analgesia technique Martin Pearson School of Veterinary Science University of Queensland, Gatton Peter Best Greencross South Tamworth Animal Hospital 88Duri Road, Tamworth

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3 Why administer an epidural analgesic? Gold standard pain relief for hind limb surgery, single injection lasts for hours Low adverse reaction risk Cheap Simple technique to learn Animal welfare The patient s wellbeing, great PR with your clients and your staff Lowers patient mortality and morbidity No client objection to cost of analgesia

4 Example: Cruciate surgery Jet 7.5 year old Bull terrier crossbred Dx Chronic rupture RH ACL & acute rupture LH ACL Repaired 16 March 2011 via Triple tibial osteotomy, a hybrid technique that both changes the tibial plateau slope and advances the tibial crest

5 Why administer epidurals? The day after surgery Jet is largely pain free and can walk comfortably

6 contraindications hypovolaemia fixed cardiac output sepsis/local skin infection coagulation disorders

7 ligamentum flavum spinal cord cauda equina CSF epidural space

8 Location of the lumbosacral space Most dorsally prominent points of the wings of the ilium

9 L7 S1

10 Lumbosacral space

11 epidural analgesia you will need: morphine (10 mg per ml, preservative free) bupivicaine 0.5% 22g spinal needles (1.5 & 3 inches) 2, 5 or 10 ml glass syringe (or plastic loss of resistance syringe) sterile paper drape syringes, gloves etc

12 preservative free morphine 10 mg/ml

13 Although it is in an outer wrap, the outside of the glass morphine vial is NOT sterile

14 0.5% bupivicaine in a theatre pack. The ampoule of bupivicaine is contained in a sterile wrapper

15 0.5% bupivicaine, the outside of this ampoule is not sterile

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17 sterile, single use, plastic loss of resistance syringe

18 glass sryinge, rinsed with deionised water & autoclaved with the plunger separate from the barrel

19 epidural analgesia dose rates 0.5% bupivicaine 0.2 ml/kg morphine (10 mg/ml) 0.1 mg/kg The drugs are mixed in the one syringe prior to injection.

20 Open all of the sterile items

21 morphine 10mg/ml

22 morphine 10mg/ml

23 bupivicaine 0.5%

24 Add the morphine to the bupivicaine and mix

25 epidural analgesia position» ventral or» lateral iv fluids» ml/kg bolus

26 Prepare as for aseptic surgery» iodine scrub» chlorhexidine/ alcohol» iodine solution epidural analgesia

27 epidural analgesia palpate dorsal prominence of wings of the ilium palpate lumbosacral space

28 epidural analgesia 22 g spinal needle insert at the lumbosacral space advance until just through ligamentum flavum

29 epidural analgesia remove stylet observe for CSF

30 epidural analgesia remove stylet observe for CSF If CSF, discard 2/3 of solution and top up morphine to 0.1 mg/kg

31 Injection of local anaesthetic into the CSF is often termed spinal anaesthesia. Compared to epidural anaesthesia, a smaller volume is used to avoid excessive cranial spread of the solution. Onset of analgesia is more rapid with spinal anaesthesia than with epidural anaesthesia. If CSF appears in the hub of the needle or can be aspirated then the loss of resistance test is not needed

32 epidural analgesia remove stylet observe for CSF observe for blood if blood is seen, withdraw needle, clean & try again

33 epidural analgesia loss of resistance test glass syringe or plastic Loss of resistance syringe tight fit on needle air or saline

34 resistance (air)

35 Loss of resistance (air)

36 Loss of resistance Disposable syringe

37 epidural analgesia inject drugs over seconds onset of action: bupivicaine 20 min lignocaine 10 min morphine 40 min

38 epidural analgesia The epidural local anaesthetic results in a blockade of the somatic nervous system and sympathetic nervous system Total peripheral resistance falls about 30% Administer IV fluids bolus prior to surgery 10-20ml/kg replacement fluids over 10 minutes

39 epidural analgesia Position in dorsal or lateral recumbency for 5-10 minutes to bathe sensory (dorsal) spinal nerve roots. :

40 epidural analgesia Position in dorsal or lateral recumbency for 5-10 minutes to bathe sensory (dorsal) spinal nerve roots. : With lateral recumbency, the patient should be positioned so that the the surgical site is dependent.

41 epidural analgesia Next... reduce concentration of volatile anaesthetic maintain light level of general anaesthesia monitor arterial pressure

42 epidural analgesia during recovery from anaesthesia: give NSAID empty bladder re-warm duration of analgesia: epidural morphine = hours epidural bupivicaine = 4-6 hours

43 epidural analgesia during recovery from anaesthesia: With» give bupivicaine, NSAID the sensory block lasts longer than the motor block.» empty Very occasionally, bladder some block will persist for more than» re-warm 12 hours after the injection. duration of analgesia: epidural morphine = hours epidural bupivicaine = 4-6 hours

44 potential problems neurological damage vanishingly rare infection extremely rare (1 in 5,000) provided aseptic technique hypotension common, but easily managed with IV fluid load Hypotension with local anaesthetics (TPR 30%) Segmental sympathetic blockade T12 greater splanchnic nerve Cardio-acceleratory sympathetic nerves RHS T1-4 Supraspinal effects especially hydrophilic morphine absorption into CSF systemic absorption

45 potential problems Constipation occasional urinary retention common, easily managed by expressing or catheterising bladder after surgery pruritis unusual inadvertent subarachnoid (spinal) injection especially cats and young dogs inadvertent IV injection causing cardiac arrest rare, treat CPR + IV 20% Intralipid 1.5ml/kg

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