Common Complications in Obstetric Anesthesia– and How to Avoid Them.

1. Common Complications in Obstetric Anesthesia– and How to Avoid Them. Tom Archer, MD, MBA UCSD Anesthesia Resident Lecture Series January 23, 2013

2. My definition of “common” • A complication you will see at least once in a career in which you do some OB anesthesia. • If you do OB anesthesia regularly, you will see most of the following complications many, many times.

3. Common OB Anesthesia Complications • Difficulty placing spinal or epidural, causing patient distress. • “Sketchy-dural” (poor epidural) • Post-dural puncture headache (PDPH) • Hypotension after neuraxial block

4. Common OB Anesthesia Complications • High spinal or epidural respiratory failure +/- hypotension • Low spinal or epidural  anesthesia failure • Intraoperative pain (incomplete block) • Can’t intubate (and can’t ventilate?) under GA.

5. Common OB Anesthesia Complications • Fetal bradycardia after CSE or epidural • Post-delivery lower extremity neuropathy

6. I am not going to discuss: • Local anesthetic or contaminant toxicity to nerves (rare in modern practice). • Direct needle trauma to nerve roots or spinal cord (rare). • Epidural abscess or hematoma (rare). • Aspiration

7. Difficulty placing spinal or epidural, with patient distress.

8. Difficulty placing spinal or epidural, with patient distress. • We have all been there, many times. At least I have. • 20-60 minutes of effort. • Patient is in tears. You are sweating. • You have called for help. They couldn’t do it either. • Is this inevitable, or is there a way to reduce the frequency of such events?

9. Making epidural placement easier for patient and doctor • “Management of expectations”: “5-10% of the time the epidural does not work properly. We will do our best…” Don’t promise perfection! • Achieve patient rapport and cooperation. • Demonstrate posture. • Reinforce positioning– patients straighten up over time when in pain. • IV fentanyl makes a big difference.

10. Making epidural placement easier for patient and doctor • If you anticipate difficult placement (e.g. an obese patient) consider IV fentanyl and ultrasound before you start. • Don’t wait until patient is in tears to give fentanyl and to use ultrasound.

11. Can ultrasound make neuraxial block easier? • Many practitioners say it is an unnecessary waste of time. I disagree, at least in selected cases. • Ultrasound can help identify: • MIDLINE (true location of spinous processes) • DEPTH TO LIGAMENTUM FLAVUM • SPINAL ROTATION, IF PRESENT

12. Paramedian Sagittal Paramedian Sagittal Oblique Most useful views Transverse

13. Spinous processes are not always directly cephalad from gluteal cleft Tense paraspinous muscles can be mistaken for spinous processes Line running cephalad from gluteal cleft

14. PLL D LF Skin surface Emitted sound Vertical skin mark Reflected sound Ultrasound probe, lateral view

15. Transverse process

16. PLL D LF Skin surface Ultrasound probe is angled until posterior longitudinal ligament is the brightest. Emitted sound Reflected sound Best insertion angle is determined for each patient by maximizing brightness of posterior longitudinal ligament (PLL) on the ultrasound screen and remembering that angle for actual needle insertion. Best angle is usually 5-15 degrees cephalad from a line perpendicular to the skin.

17. Dura /ligamentum flavum complex Posterior longitudinal ligament Interlaminar foramen (black shape inside white rectangle)

18. Vertical skin mark #1, centered on probe Horizontal skin mark #2, centered on level of probe (between spinous processes) Underlying spinous process (dark blue) Insertion point is the intersection of horizontal and vertical lines through skin marks. Line running cephalad from gluteal cleft

19. PLL D LF Skin surface 10 cm Ultrasound probe Best insertion angle Ultrasound enables us to measure distance to the ligamentum flavum to within a centimeter or so. Estimate, if incorrect, is almost always too small, due to compression of adipose tissue during the measurement.

20. “Sketchy-dural” (poor epidural)

21. “Sketchy-dural” • They happen, no matter how good you are. • “Management of expectations.” Don’t promise the patient a perfect epidural. • That said, here is my advice to minimize impact of sketchy-durals on our care…

22. “Sketchy-dural” • Be honest with yourself. Many sketchy-durals are simply not in the right place. • Check what is really going on, with ice– systemic fentanyl can mask a non-epidural. • Have a low threshold for replacement.

23. “Sketchy-dural” • A disadvantage of IV fentanyl is that the analgesia it provides can mask a poor epidural. • Ask the patient how her legs feel. The answer should be “numb” or “tingly”. “Fine” is NOT a good answer– it means there is no block! • Epidurals requiring more than one MD bolus have a higher failure rate for CS.

24. “Sketchy-dural” • What exactly is the problem? Talk with and examine the patient. • Just doesn’t work at all? replace • One sided? bolus with less-affected side down. Next step pull back one cm. Next step replace • “Hot spot” but otherwise OK? Position side with “hot spot” downwards and bolus with stronger local anesthetic + epinephrine + fentanyl.

25. “Sketchy-dural” • Think about other causes of “abnormal” pain fetal head pressing on nerves, uterine rupture, placental abruption, “intradural placement.” • There should be no pain (or much sensation at all) with an epidural injection. • Discomfort in the back during epidural injections suggests intramuscular or subcutaneous injection.

26. “Sketchy-dural” • Consider ultrasound the second time (or the first time!) to confirm: • MIDLINE (true location of spinous processes) • DEPTH to ligamentum flavum • ROTATION of the spinal column

27. “Sketchy-dural” goes to CS. • Can you do a spinal on top of a “sketchy-dural”? • Yes, but do it carefully and understand that high spinal may occur. • CSE with low intrathecal dose, or titrated epidural are options.

28. Post dural puncture headache(“Spinal headache”)

29. Post dural puncture headache(PDPH) • Third most common cause of lawsuit in OB anesthesia. • Can be disabling and distressing, particularly for a mother trying to take care of a newborn and a household.

30. Post dural puncture headache(PDPH) • Third most common cause of lawsuit in OB anesthesia. • Can be disabling and distressing, particularly for a mother trying to take care of a newborn and a household.

31. PDPH • Midline frontal and/or occipital. Not lateralized! • May extend into neck (stiff neck) • Worse with upright posture (usually immediate onset, may be delayed 20 minutes) • Relief with flat posture (usually immediate).

32. PDPH • May be associated with diplopia (abducens palsy) and muffled hearing or tinnitus. • May be associated with N+V.

33. But is it really PDPH? • The key question: Could it be something else? • If you Rx PDPH and it is something else you incur two problems: unnecessary treatment risk AND missed Dx. • It could be: lactation HA, migraine, subdural hematoma, brain tumor, AVM, cortical vein thrombosis, dural sinus thrombosis, etc.

34. Yes, it is PDPH • Conservative therapy vs. Blood patch? • Conservative therapy: NSAIDs, other oral analgesics, caffeine, fluids, salty foods. • Epidural blood patch (EBP): 10-30 mL of patient’s blood injected into epidural space. • EBP complications: back pain, leg paresthesias (common), epidural abscess or adhesive arachnoiditis (rare).

35. In favor of EBP • Severe disability, >24 hours of Sx. • Patient confined to bed– unable to function • Associated signs + Sx of decreased ICP (abducens palsy, hearing changes, N+V)

36. In favor of conservative therapy • Uncertain Dx. • Patient uncomfortable but able to function. • If they are sitting up in bed, or walking, when I enter the room, I am hesitant to do a blood patch.

37. PDPH etiology • Traditional theory: loss of CSF leads to brain “settling down” in skull, with resultant traction on dura and nerves • Vasodilation theory: loss of CSF leads to translocation of CSF to lumbar area with upright posture. Volume in skull must remain constant, hence vasodilation + HA. • Therapeutic efficacy of caffeine and vasoconstrictors supports vasodilation theory

38. Hypotension after labor epidural

39. Hypotension after labor epidural • Occurs VERY commonly. 30-40% of the time? • Consider low dose prophylactic phenylephrine or ephedrine after block placement.

40. Hypotension after labor epidural • 95% of fetal distress after epidural is due to hypotension. • The other 5% may be “uterine hypertonus” due to rapid pain relief (discussed later). • Both things might be happening. • When there is fetal distress palpate uterus!

41. Hypotension after labor epidural • Routine therapy for hypotension (in absence of uterine hyperstimulation) is: Position change (Left or right side down). Fluid bolus Vasopressors Oxygen, if there is fetal bradycardia.

42. Hypotension with labor epidural • Treat hypotension early, treat often. • Prevention with low-dose vasopressor has very little downside. • Is there a role for non-invasive cardiac output measurement in labor to detect occult IVC obstruction?

43. Physiology of post-block hypotension

44. Sympathetic efferents exit spinal cord from T1 to L2. Low sympathectomy: Blockade of T5-L2 Splanchnic vasodilation and pooling. Reduced venous return (CO), especially with IVC obstruction. Reduced SVR. 17 http://health.usf.edu/nocms/medicine/anatomylab/modules/pelvic_autonomic_module/pelvic_page02.html

45. Sympathetic efferents exit spinal cord from T1 to L2. High sympathectomy: Blockade of T1-T4  warm vasodilated hands, further reduced SVR, Horner’s syndrome, ? bradycardia. Blockade of T5-L2 Splanchnic vasodilation and pooling. Reduced venous return (CO), especially with IVC obstruction. Reduced SVR. 18 http://health.usf.edu/nocms/medicine/anatomylab/modules/pelvic_autonomic_module/pelvic_page02.html

46. T5-L2 sympathectomy causes pooling of blood in the splanchnic vessels, reducing venous return and CO. 20

47. Splanchnic vasculature has alpha and beta receptors at multiple sites. Alpha 1+2 constrict splanchnic capacitance vessels Alpha 1+2 constrict splanchnic arteries Beta 2 dilates hepatic veins 21 Figure modified by Archer TL

48. Decreased venous return and cardiac output due to sympathectomy is exacerbated by obstruction of IVC. 22

49. If IVC is open, venous return is unimpeded and cardiac output is maximized. 23 http://www.manbit.com/OA/f28-1.htm Manbit images

50. Given late! 29 Diagram modified by Archer TL