Phil Popham Royal Women ’ s Hospital, Melbourne

1. Failed spinals in obstetrics: cause, prediction, prevention and management • Phil Popham • Royal Women’s Hospital, Melbourne

2. Failed spinals in obstetrics: cause, prediction, prevention and management I’m sure that was in the right place... • Phil Popham • Royal Women’s Hospital, Melbourne

3. Plus ça change: “..for successful analgesia it is necessary to enter the lumbar dural sac effectually with the point of the needle, and to discharge through this, all the contemplated dose of the drug, directly and freely into the cerebrospinal fluid, below the termination of the cord.” Barker A. Clinical experiences with spinal analgesia in 100 cases. Br Med J 1907;665–676

4. The steps to a successful block Find, and fully pierce, the dura with the needle Inject the planned dose of LA Achieve satisfactory spread in CSF Achieve appropriate drug action on nerve roots

5. To paraphrase:

6. To paraphrase: Right place

7. To paraphrase: Right place Right drug

8. To paraphrase: Right place Right drug Right dose

9. What could possibly go wrong?? All as straightforward as parking a car in the garage...

11. What could possibly go wrong??Failure: Partial Complete Incomplete block • Complete failure

12. Partial failure... • Extent: failure to reach a given dermatomal level • Quality: failure to produce adequate block • Duration: failure to last as long as needed

13. ...is diagnosed by... • Extent: modality of checking block, interval since injection • Quality: modality of checking block, interval since injection, need for other supplementation • Duration: when it starts to hurt...

14. Complete failure... • Complete absence of sensory or motor block

15. ...is diagnosed by... • Complete absence of sensory or motor block • Despite waiting “long enough” for the block to develop • 15 minutes Cochrane database Syst Rv. 2004 CD 003765

16. Incidence of failure • Prospective • 3.1% in 1891 patients • Tarkkila P. Incidence and causes of failed spinal anesthetics in a University Hospital: a prospective study. Reg Anesth 1991; 16: 48–51 • 4% in 200 patients • Munhall R, Sukhani R, Winnie A. Incidence and etiology of failed spinal anesthetics in a university hospital. Anesth Analg 1988; 67: 843–8

17. Incidence of failure • Retrospective • 2.7% in 2314 patients • Pan PH, Bogard TD, Owen MD. Incidence and characteristics of failures in obstetric neuraxial analgesia and anesthesia: a retrospective analysis of 19,259 deliveries. Int J Obstet Anesth 2004; 13: 227–33 • 17% in 100 patients • Levy J, Isles J, Ghia J, Turnbull C. A retrospective study of the incidence and causes of failed spinal anaesthetics in a university hospital. Anesth Analg 1985; 64: 705–10

18. Mechanisms of failure • Anatomical • Technique • Drug

19. Anatomical failure

20. Anatomical failure

21. Anatomical failure • Inability to locate intrathecal space: • Positioning • Anatomical abnormality (ank spond, kyphosis, kyphoscoliosis, lordosis) • Hardware (Harrington rods) C,P C,P C,P

22. Anatomical failure • Identification of fluid aspirate • Intradermal cyst (most commonly sebaceous cysts from hair follicles) • Lipaceous material, discernible click on cyst puncture, no free flow of fluid • May contain keratin particles C,P Kell, Gudin, Brull. J Clin Anaesth 1996;8;603–604

23. Anatomical failure • If impalpable, all intradermal cysts are likely to be small, with little free fluid or with viscous content. • Free aspiration of fluid therefore unlikely. C,P

24. Anatomical failure • Identification of fluid aspirate • LA infiltration under pressure may create fluid filled cyst • Aspirated fluid will have different composition to CSF C,P Boon, Abrahams, Meeting. Clin Anat 2004;17;544–553 El-Behesy, James, Koh, Hirsch, Yentis. Br J Anaesth 1996;77;784–785

25. Anatomical failure • Intrathecal sac • Dural ectasia: large lumbosacral dural sac • Repeated injections needed • Noted in Marfan’s syndrome (even during CSA) P Hirabayashi et al. Can J Anaesth 1996;43;1072–5 Lacassie et al. Br J Anaesth

26. Anatomical failure • Intrathecal sac • Trabeculae in subarachnoid space • Presence of a subdural space P P Parkinson Am J Anat 1991;192;498–509 Haines Anat Rec 1991;230;3–21 Haines Neurosurgery 1993; 32;111–120

27. Anatomical failure William of Ockham (1285–1349) English Franciscan friar Law of parsimony or succinctness

28. Frustra fit per plura quod potest fieri per pauciora

29. Frustra fit per plura quod potest fieri per pauciora It is futile to do with more things that which can be done with fewer

30. Frustra fit per plura quod potest fieri per pauciora It is futile to do with more things that which can be done with fewer Of competing hypotheses which are equal in other respects, select the one which makes the fewest new assumptions.

31. Frustra fit per plura quod potest fieri per pauciora It is futile to do with more things that which can be done with fewer Of competing hypotheses which are equal in other respects, select the one which makes the fewest new assumptions. The simplest explanation is more likely to be the correct one

32. Anatomical failure Tarlov cysts

33. Tarlov cysts (1938) • Extradural meningeal dilatations • Encase posterior spinal nerve root sheaths • Mainly lumbosacral • Idiopathic, post-trauma or surgery • Radicular pain • Narrow neck in continuity with CSF • Current adult incidence estimated 4.5–9%

36. Failure of technique • Partial penetration of dura • Partial dislodgement of needle • Loss of injectate

39. BJA 2009;102;739–748

40. BJA 2009;102;739–748

41. Failure of drug • Wrong drug or agent...

42. Toxic epidural ravages mother Julie Robotham The Age, August 21, 2010 ...Epidural administration of chlorhexidine - used to clean skin before injections and strong enough to neutralise resistant hospital bacteria - is so rare that Ms X's doctors have identified only one other case. Angelique Sutcliffe, from Britain, was paralysed for life after the chemical entered her epidural in 2001. But this was just a droplet - a fraction of the eight millilitres infused into...

43. Failure of drug • Wrong dose • Agent • Baricity • Positioning • Often offset by use of larger than needed dose

44. Failure of drug • ED95 bupivacaine for C/S: 11.0–11.2 mg • Low dose spinal may use 5–6 mg combined with opiate in attempt to minimise side effects • But at the expense of reducing safety margin for adequate anaesthesia Anesthesiology. 2004 Mar;100(3):676-82

45. Loss of injectate • Heavy bupivacaine 0.5% 2.4 mL plus fentanyl 15µg: • each drop from 5 mL syringe = 0.06 mL • each drop from 2 mL syringe = 0.045 mL • Volume lost during spinal injection occurs in about 65% cases, when: • loss from 2 mL syringes is greater, but small (0.06 mL) Randall & Yentis, IJOA 2002;11;23

46. Drug batch failure • IJOA 2003/2004 • UK, NY • Specific batch numbers identified • Unopened vials returned to manufacturer, all complied with QC • In USA, opened vials sent to FDA, same result. Wood M, Ismail F. Inadequate spinal anaesthesia with 0.5% Marcain Heavy (Batch 1961). International Journal of Obstetric Anesthesia 2003; 12: 310–311

47. pH effects • Retrospective review of CSA in orthopaedics • Inadequate block produced by incremental 0.2% bupivacaine (diluted with N/S from 0.5%) treated by 1% lidocaine (diluted with N/S from 2%) • Postulated that: • dilution with N/S lowered pH of both solutions • greater fall in non-ionised bupivacaine led to more failures • Lidocaine rescue increased total dose of LA and increased pH, promoting greater block

48. 0.5% bupivacaine pH = 5.4 • 0.5% bupivacaine plus fentanyl (10µg/mL) pH = 4.3 • For pH to produce significant effects on LA availability, there would have to be tissue acidosis...

49. LA resistance • Most commonly suggested with a family or personal history of “failed” LA injections • Postulated sodium channel mutation...

50. LA resistance • Most commonly suggested with a family or personal history of “failed” LA injections • Postulated sodium channel mutation... • ...that has yet to be identified