Anesthesia for cesarean section

1. Anesthesia for cesarean section Tom Archer, MD, MBA UCSD Anesthesia

2. A unique psychosocial surgery

3. Outline • C-section – a unique psychosocial surgery • How the OB anesthetist should behave. • Evolution of techniques • Neuraxial block physiology and management • GA physiology and management. • Management of common problems

4. C-section – a unique psychosocial surgery • Psychological / interpersonal aspects • Unique surgery, happy event gone awry. • Strike a balance between “happy event” and “risky surgery”. • Most patients are awake– and want to be. • Team approach (patient, family, nursing, OB, anesthesia) • Support person present in OR. • Family members in the labor room (face them). • Discretion about medical info– JW, drug use, previous abortions, etc.

5. Anticipate and be available • Know every patient on the floor. Introduce yourself early. • Be accessible to OBs and nurses. • Get informed early about potential problems (airway, obesity, coagulopathy JW, congenital heart disease) • Remember the basics (IV access, airway)

6. Anticipate and be available • We need a certain knowledge of OB to know what is going to happen. Try to think one or two steps ahead. • “Placenta isn’t out yet in room 7” • “The lady in 6 has a pretty bad tear.” • “Strip review in 3, please.” • “We can’t get an IV on the lady in 4.” • “Can you give us a whiff of anesthesia in 8? We don’t need much.”

7. Evolution of technique • Last 30 years: decreasing use of GA, now about 5% of cases. Was 20-30% in 70’s at UCSD. • Epidural was “all the rage” in 70’s and 80’s. • SAB (or epidural) are now preferred anesthetics.

8. Anesthesia for C/S—basic interventions • Happy event (sort of) • Gastric acid neutralization • Left uterine displacement • Fluid loading • Supplemental oxygen • Support person in room (regional only)

9. Anesthesia for C/S—Complications • Sympathectomy / hypotension • Nausea • Bradycardia • High spinal / respiratory paralysis • Aspiration • Difficult intubation • Local anesthetic toxicity • Failed regional anesthesia • Persistent neurological deficit

10. C/S red flags • “I don’t feel so good…I think I’m going to throw up…” (Hypotension until proven otherwise). • “Doc, I feel like I’m not getting enough to breathe…” • The “floppy arm sign.” • The “shaking head sign.”

11. Spinal-- advantages • Uniquely appropriate in C/S (happy event). • Really amazing when you think about it. • Awake and smiling. • Arms and hands are normal. • Major surgery inside the abdomen. • Quick, solid, simple, reliable, pretty safe. • LA + narcotic gives great block. • Can give long-acting analgesia (intrathecal MS)

12. Regional anesthesia for c/s in Turkey (SOAP outreach)

13. Spinal-- disadvantages • Fixed duration (unless continuous spinal). • Rapid onset of sympathectomy or high block. • Small chance of PDPH.

14. SAB– absolute contraindications • Patient refusal • Uncorrected hypovolemia • Clinical coagulopathy • Infection at site of injection

15. SAB– obsolete contraindication • Severe pre-eclampsia— • Not associated with increased chance of severe hypotension with neuraxial block. • Show me the literature if you disagree.

16. SAB– relative contraindications • Spinal cord, LE nerve disease. • Spinal deformity, instrumentation • Back problems / fear of block • Laboratory coagulopathy • Bacteremia

17. SAB– relative contraindications • Potential for hypovolemia • Stenotic cardiac valve lesions (?) • Pulmonary hypertension (?)

18. Basic C/S monitoring • Talk with the patient! • Does her face display anxiety? • “Take a deep breath!” • Have her squeeze your fingers • What is her hand temperature? • Are the hand veins dilated? • “Do your hands feel normal or do they feel a little numb?”

19. SAB / epidural cause sympathectomy • Dilation of capacitance vessels (70-80% of blood volume) • May cause drop in CO • Dilation of resistance arterioles (0.1-0.4 mm diameter). • Drop in SVR

20. SAB / epidural cause sympathectomy www.cvphysiology.com/Blood%20Pressure/BP019.htm

21. SAB / epidural cause sympathectomy www.cvphysiology.com/Blood%20Pressure/BP019.htm

22. SAB / epidural cause sympathectomy rfumsphysiology.pbwiki.com/Characteristics+of...

23. 38 y.o. female, repeat c/s, 420 #, gestational hypertension, continuous spinal: fall in SVR, rise in CO with onset of block. Increased SVR with phenylephrine.

24. When is sympathectomy(low SVR) bad? • BP = CO x SVR • Whenever you can’t increase CO! • Uncorrected hypovolemia • IVC compression • Stenotic valve lesions • Pulmonary hypertension

25. Pulmonary capillaries LV dilation / hypertrophy Tricuspid Aortic stenosis Mitral Pulmonic Aortic stenosis at rest Cardiac output not sufficient to cause critically high LV intracavitary pressure / LV failure. Resistance arterioles

26. Pulmonary capillaries (edema) LV failure / ischemia Tricuspid Aortic Stenosis Pulmonic Mitral Aortic stenosis with SAB: increased cardiac output / arteriolar vasodilation: Decreased SVR Fall in systemic BP and / or increase in LV intracavitary pressure ischemia or LV failure. Resistance arterioles– decreased SVR

27. 38 y.o. female, repeat c/s, 420#, continuous SAB. Delivery with increased CO at 17, oxytocin 3 U bolus at 18, phenylephrine at 19

28. When is sympathectomy(low SVR) bad? • With bolus of other vasodilator (oxytocin)

29. Oxytocin 10 u bolus

30. Both delivery and oxytocin cause increase in cardiac output. Delivery of baby Oxytocin 5U IV push Phenylephrine bolus for hypotension C/S under epidural in pt with previous peripartum cardiomyopathy (May 30, 2007)

31. When is sympathectomy(low SVR) bad? • When drop in SVR could exacerbate R > L shunt. • ASD • VSD • PDA

32. Decompensated patient with REAL RL shunt. LA LV Decreased SVR desaturation Ao PA Increased pulmonary vascular resistance desaturation RA RV Decompensated patient with ASD, VSD or PDA-- Decreased SVR or increased pulmonary vascular resistance  increased RL shunt and increased arterial desaturation.

33. 38 y.o. female, repeat c/s, 420 #, gestational hypertension, continuous spinal: fall in SVR, rise in CO with onset of block. Increased SVR with phenylephrine.

34. Compensated patient with POTENTIAL RL shunt. LA LV High SVR, Minimal RL shunt Ao PA RA RV Low pulmonary vascular resistance Normal, compensated patient with ASD, VSD or PDA-- high SVR and low pulmonary vascular resistance minimal RL shunt.

35. JW with previa / accreta for c-hyst. GA. Induction at 7, 8, intubation before 9, incision after 9. Note rise in SVR and fall in CO with GA.

36. How to prevent a sympathectomy from being a problem • Keep the SVR up with a vasopressor like phenylephrine.

37. Preventing or treating hypotensionfrom sympathectomy: augment venous return (CO). • Trendelenburg (empty capacitance vessels into central thoracic veins) • LUD (get pressure off vena cava) • Fluid loading (fill capacitance vessels) • Crystalloid • Hetastarch • Arteriolar constrictors (inc SVR) • Ephedrine, phenylephrine • Venous constrictors (inc venous return) • Ephedrine, phenylephrine

38. Hypotension with SAB or epidural • Pre-load does not prevent reliably. • 500 mL hetastarch better than 1500 mL crystalloid. • First symptom is nausea or “I don’t feel so good.”

39. Hypotension • Use phenylephrine (neosynephrine) if tachycardia. • Use ephedrine if bradycardia. • Use atropine if severe bradycardia. • Glycopyrolate works slowly.

40. www.sympathectomy.co.uk/ETS.php Sympathectomy

41. Sympathectomy

42. Endoscopic transthoracic sympathectomy Virtually all patients immediately develop warm, dry hands and leave the hospital the same day as surgery. www.sd-neurosurgeon.com/.../hyperhidrosis.html

43. Hyperhydrosis Rx’d with T3 sympathectomy

44. Horner’s syndrome

45. Horner’s syndrome

46. Bradycardia • With hypotension: High block of “cardioaccelerator fibers” (T1-T5). • Also can be reflex bradycardia with hypertension from phenylephrine

47. Inc SVR and BP with bradycardia from neo 50 mcgm at 4. Brady occurs after SVR and BP changes.

48. Left Uterine Displacement(LUD)

49. Colman-Brochu S 2004

50. http://www.manbit.com/OA/f28-1.htm