Hypotension and respiratory failure after epidural test dose in a patient from the Birth Center.

1. Hypotension and respiratory failure after epidural test dose in a patient from the Birth Center. Tom Archer, MD, MBA Clinical Professor and Director, Obstetric Anesthesia UCSD Department of Anesthesiology November 7, 2012 1

2. UCSD Birth Center (4th floor Hillcrest hospital): The practice philosophy is “natural” and “homelike” childbirth, yet with immediate access to advanced care for mother and infant. We strive for an excellent relationship between midwives, obstetricians, nurses, anesthesiologists. 2

3. “…labor support techniques that can help women give birth with little or no pain medication: • Walking during labor • Hydrotherapy (shower or tub) • Birth stools • Birth balls • Breathing techniques • Massage • Music” UCSD Birth Center website 4

4. IV fluids and IV pain meds are available if needed. • “Should the need arise, intravenous fluids and pain medication are available. • If the pain is too challenging, or if a complication should arise, the option of transferring to the Labor & Delivery Unit for epidural anesthesia or more intensive medical care is available.” UCSD Birth Center website 5

5. ROM at home 0305 “Strong rectal pressure” 6-7 cm dilated. Encouraged to get up to shower. Doula present. 2320 A long, painful labor is documented in this time line. 0808 Breakfast 1646 Admit to BC. Mild ctx q5-7 min. “Pt desires augmentation with castor oil.” 0540 Admit to L&D (awaiting BC bed). Not in labor. 2018 Painful contractions. Squatting at bedside. Uses birthing ball. FOB and mother providing labor support. 6

6. 0441 Pt breathing hard through ctx. Pt reports a strong urge to push but able to breathe through them 0040 Out of shower and into tub. 0200 CNM at bedside. Cervix swollen. Patient told not to grunt with contractions. Pt requests IV pain meds. 0211 Out of tub. Unable to void. To bed- sve by cnm, 7+/edematous, anterior lip more edematous/0 station. Will order fentanyl for pain relief/discourage involuntary pushing. Reeval when fentanyl wears off and prn. FHTs 120's, audible increases, no decreases. 0324 Pt inquiring about an epidural due to increase in pressure with Ctx but very hard to breathe through them. Pt received more IV fentanyl per pt request. Straight cath done due to unable to void (pt able to void once since 2100). Pt continues to breathe hard through ctx to try and not push 0414 Dozing between uc's s/p fentanyl. Cont. To have urge to push/invol. Push w/peak of uc's. FHTs 120's. UCs q 3mins. SVE by CNM 9/C, edematous anterior lip/1+station. Continue expectant management. Anticipate progression to C/C and NSVB. 7

7. CNM suggests pt get an epidural due to swollen anterior lip and pt with uncontrollable urge to push. Pt and family agrees with POC 0600 0604 Continues to push involuntarily against rim cervix with thick anterior lip- soft, stretchy, reduces, but them comes down again. Vtx at 1-2+ station. Discussed w/Dr. M. Alunni- agrees with CNM plan to transfer to L+D for CLE. FHTs stable. UCs q 3 mins. Charge RN aware. 0615 Pt to L&D. Pt… denies any headache, blurred vision or epigastric pain. Reports +FM. Placed on monitors, MDs aware of arrival. Family at bedside, doula at bedside, call bell within reach. 8

8. Prior to epidural: • Painful labor x 10 hours. • Swollen cervix stuck at 6-7 cm dilation. • Straight cath x 1 / emesis • Multiple doses of fentanyl 9

9. Epidural test dose • Given to “rule out” IV or IT injection. • 3 mL 1.5% lidocaine with epinephrine 5 mcgm/mL (1:200,000). • 45 mg lidocaine • 15 mcgm epinephrine 10

10. Epidural test dose • If IV  increase of HR by 20-30 bpm within one minute. Uterine contractions can also cause tachycardia. • If IT numb/weak legs within 2-3 minutes + “sympathectomy”. • Negative test dose does not assure proper epidural placement! 11

11. Our case is not unique. Reg Anesth. 1996 Mar-Apr;21(2):119-23. High spinal anesthesia after epidural test dose administration in five obstetric patients. Richardson MG, Lee AC, Wissler RN. Source Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA. mrichardson@ccmail.anes.rochester.edu Abstract BACKGROUND AND OBJECTIVES: A commonly used test dose in parturients receiving continuous lumbar epidural analgesia for labor consists of 3 mL of dextrose-free 1.5% lidocaine with 1:200,000 epinephrine. METHODS: of 1,962 obstetric epidural anesthetics administered over a 17-month period, unintentional subarachnoid placement of the epidural catheter was detected by injection of the test dose in five laboring patients. The characteristics of the resulting subarachnoid blocks were studied. RESULTS: After negative aspiration for cerebrospinal fluid in each case, test dose injection resulted in the rapid onset of high sensory block with associated motor and sympathetic block, accompanied by significant hypotension requiring aggressive treatment. CONCLUSIONS: While this test dose appears to be a sensitive indicator of an unexpected subarachnoid catheter, the resulting excessive spinal blocks in these laboring patients raise the question of its safety. 12

12. Question • Is it safe and reasonable to give vasopressors prophylactically when a high spinal occurs? 13

13. Prophylactic ephedrine and phenylephrine • Wise decision to give a combination of phenylephrine and ephedrine to this patient to prevent problems which probably would have developed. • High spinal is both a respiratory and a circulatory emergency. 14

14. Questions • Why does neuraxial anesthesia sometimes cause hypotension? • Besides hypotension, what other signs and symptoms accompany a high block? 15

15. Major syndromes for high spinal • Hypotension • Bradycardia • Respiratory failure • Cardiac arrest • Specifically: cardiac arrest in pregnant patient. 16

16. 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

17. 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

18. Most vascular resistance is supplied by the muscular arterioles, measuring 0.1mm in diameter and smaller. Sympathectomy dilates resistance arterioles, reducing SVR. 19 http://www.cvphysiology.com/Blood%20Pressure/BP019.htm http://www.biosbcc.net/doohan/sample/htm/vessels.htm

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

20. 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

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

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

23. If IVC is obstructed, venous return is blocked and cardiac output is reduced. 24 http://www.manbit.com/OA/f28-1.htm

24. Blood pressure • (MAP-CVP) = CO x SVR. • MAP = CO x SVR CO depends on venous return, which depends on venous tone and IVC patency. SVR depends on resistance of arterioles (0.1 mm diameter and smaller). 25

25. Cardiac arrest with high spinal • Why? • Hypoxia • Hypotension • Bradycardia 26

26. 27

27. Bradycardia after high spinal:two common explanations • Blockade of T1-T4 “cardioaccelerator fibers”  unopposed vagal tone bradycardia • Bezold-Jarisch reflex: decreased right atrial and ventricular filling bradycardia • (B-J reflex can be thought of as an attempt to “give time for the heart to fill with blood.”) 28

28. Given late! 29 Diagram modified by Archer TL

29. Vigilance! • Talk with patient for test dose. “Heart pounding, legs numb or weak”. Have Ambu bag and pressors immediately available. • Give 2-3 minutes for test dose to be positive. Consider dosing epidural fentanyl after test dose since it will augment block but not “burn any bridges.” • Stay with patient 15-30 minutes after initiation of block to r/o hypotension, hyperstimulation or excess block. Do charting. Start infusion. 30

30. Routine monitoring after neuraxial block for C-section • Talk with patient (“How are you doing…?,” “Are your legs feeling different…?”) • “Take a deep breath.” Observe. • “Squeeze my fingers” (bilateral) • Warms hands and / or dilated hand veins? 31

31. Treatment of spinal induced hypotension and bradycardia: • “Left lateral position/O2/fluids/vasopressors” • Ephedrine and possibly atropine (or glycopyrrolate). • Early use of epinephrine if these are not effective. • ?Airway support (Ambu bag and ? Intubation) 32

32. Cardiac arrest in labor room– do the CS in the labor room! • “Four minute rule”– start CS within 4 minutes of arrest. Deliver baby within 5 minutes to avoid neonatal brain damage. • “Our findings imply that perimortem cesarean delivery during actual arrest would require more than 5 minutes and should be performed in the labor room rather than relocating to the operating room.” 33 Obstet Gynecol. 2011 Nov;118(5):1090-4. Labor room setting compared with the operating room for simulated perimortem cesarean delivery: a randomized controlled trial. Lipman S, Daniels K, Cohen SE, Carvalho B.

33. Pt given test dose…at this time, pt states she feels like she is going to fall, pt supported and placed lying on left side at this time. 0645 FHR remains in the 90s, FSE applied at this time. 0651 Time out and skin incision. 0703 Terbutaline given en route 0655? 0654 Pt transferred to DR 3 for emergency cesarean section 0704 Uterine incision 0646 OB resident called to room as FHR deceleration at this time, pt turned lying right side, 02 10 L via FM and fluid bolus infusing. Pt examined as charted at this time. 0650 Pt awake, unable to grasp fingers, ambu mask on at this time. Anesthesia remains at bedside 0702 Splash prep to abdomen, foley placed, pt lying on table with left lateral displacement, bovie pad to right thigh, venodynes bilateral LE. 0705 Viable baby boy born at this time, infant handed to peds per MD 0650 Called to LDR 8 for FHR decel x 3mins- s/p "high" CLE. Dr. Alunni at bedside evaluating pt. To OR. 34

34. Fetal distress after high spinal—Why? • Hypoxia– not present in this case. • Hypotension– probably avoided in this case. • Reduced placental perfusion (aortocaval compression)– possibly present in this case. • “Hyperstimulation” 35

35. What is the “big picture” of fetal distress in labor? 36

36. Figure 1 Healthy, abundant uteroplacental perfusion Upper body Minimal collateral venous return to heart via lumbar and azygos system Uncompressed aorta and iliac arteries Open IVC Fetal O2 supply 37

37. Figure 2 Uterine contractions periodically deprive placenta of perfusion. Upper body Uncompressed aorta and iliac arteries Open IVC Minimal collateral venous return to heart via lumbar and azygos system Fetal O2 supply Uterine contractions 38

38. Figure 3 Hyperstimulated uterine contractions deprive placenta of perfusion even more. Upper body Uncompressed aorta and iliac arteries Open IVC Minimal collateral venous return to heart via lumbar and azygos system Fetal O2 supply Hyperstimulated uterine contractions 39

39. Figure 4 Aortocaval compression reduces placental perfusion pressure. Upper body Increased collateral venous return to heart via lumbar and azygos system Compressed IVC Compressed aorta and iliac arteries ACC Uterine mass ACC Fetal O2 supply 40

40. Figure 5 Aortocaval compression and hyperstimulation produce hypoxia. Upper body Increased collateral venous return to heart via lumbar and azygos system Compressed IVC Compressed aorta and iliac arteries ACC Uterine mass ACC Fetal O2 supply Hyperstimulated uterine contractions 41

41. Intrauterine resuscitation? • Remember this concept! • Is fetal distress due to something that can be fixed in utero (e.g. hypotension or uterine hypertonus)? If so, CS may be avoidable. • If fetal distress is due to something irreversible, that cannot be fixed in utero (e.g. placental abruption) then CS is needed. 42

42. “Hyperstimulation”– excessive uterine contractions. Common syndrome is rapid pain relief in the presence of oxytocin augmentation. FIGURE 22-2Prolonged fetal bradycardia resulting from excessive oxytocin-induced hyperstimulation of the uterus after intravenous infusion of meperidine (Demerol) and promethazine (Phenergan) into the same tubing. The heart rate is returning to normal at the end of the tracing, after appropriate treatment (signified by the notes “Pit off,” “O2 6 L/min,” and “side”). Note that fetal heart rate variability was maintained throughout this asphyxial stress, signifying adequate central oxygenation.  43

43. Intrathecal opioids are associated with fetal bradycardia– mechanism uncertain. 44

44. Abrao et al (2009) in a RCT found CSE with sufentanil and bupivancaine to be associated with more uterine hypertonus than CLE. IUPC was used for intrauterine pressure measurement. 45

45. Uterine “hyperstimulation” • Especially associated with IT lipid soluble opioids (sufentanil, fentanyl) but can occur after rapid pain relief by any means. • Often associated with oxytocin (Pitocin) augmentation of labor. • Can occur up to 30 minutes after administration. 46

46. Uterine “hyperstimulation” • Proposed mechanism: pain relief decreased maternal epinephrine decreased uterine relaxant effect of epinephrine increased uterine tone placental insufficiency. 47

47. “Events were explained to family by anesthesia team” Very important to talk with the patient after an adverse outcome. Listen. Learn what happened from the patient’s point of view. Apology for what happened. Is not an admission of guilt. “We are sorry that this happened.” 48

48. The fetus floats at the far end of a tunnel of oxygen delivery. If the tunnel is blocked, the fetus dies. 49 http://darksideofthecatalogue.wordpress.com/2011/11/22/light-at-the-end-of-the-tunnel-is-glowing-thing-23-12/

49. The End