Anesthesia for Obstetrics Department of anesthesiology Cui Xiao Guang

1. Anesthesia for Obstetrics Department of anesthesiology Cui Xiao Guang

2. PHYSIOLOGIC CHANGES OF PREGNANCY 1 • Cardiovascular System : cardiac output , heart rate • Hematologic System : blood volume increases by up to 45% , red cell volume increases by only 30% --physiologic anemia

3. PHYSIOLOGIC CHANGES OF PREGNANCY 2 • Respiratory System : increase in the respiratory minute volume and work of breathing • Gastrointestinal System : endotracheal intubation • Renal System : GFR rises 50% ; glycosuria • Central Nervous System :↑sensitivity to anesthetics.

4. PLACENTAL TRANSFER OF ANESTHETIC DRUGS • Simple diffusion • Active transport • Pinocytosis • Readily cross : low molecular weights, high lipid solubility , non-ionized • Approximately 50% bypasses the liver.

5. Morphine • Placental transfer is rapid • Mother: uterus reactiveness↓ orthostatic hypotension nausea vomiting delayed gastric emptying • Fetus: respiratory depression

6. Pethidine • Most commonly usedduring labor • intramuscular dose : 50 -100 mg • Time of IM: before expulsion 1 h or 4 h • uterine contraction, frequency and intension ↑

7. Fentanyl Alfentanil Sufentanil • Placental transfer is rapid • Low dose: 10 -25 µg fentanyl or 5-10 µg sufentanil in subarachnoid space • PCEA: low dose of fentanyl and 0.1%- 0.3% ropivacaine

8. Tramadol • Placental transfer • No inhibiting uterine contraction • No Respiratory depression

9. Diazepam • Readily cross the placenta • Half-lives : 48 hours • Problems :sedation, hypotonia, cyanosis, impaired metabolic responses to stress.

10. Midazolam • Plasma protein binding: 94% • Respiratory depression: depended on dose 0.075 mg/kg – no problem 0.15 mg/kg – different degree

11. Chlorderazin • Preeclampsia and eclampsia • IM：12.5 – 25 mg • Overdose: central inhibition

12. Promethazine • Prevent emesis • Appears in fetal blood within 1 to 2 minutes after intravenous injection in the mother • Reaches equilibrium within 15 minutes

13. Droperidol • Pregnant woman: 慎用 • Apgar score ↓

14. Thiopental sodium • Neonatus sleep: little • Premature and intrauterine embarrass: carefully using

15. Ketamine • High doses (greater than 2 mg/kg) may cause low Apgar scores and abnormalities in neonatal muscle tone • Labor painsof uterine contraction • Uterine muscular tension and contraction force • Contraindication: psychosis, gestational hypertension syndrome or preeclampsia, metrorrhexis

16. Propofol • Recommendation: induction: <2.5 mg/kg maintenance: 2.5-5.0 mg/kg • Discontinue gravidity only

17. N2O • Placental transfer is rapid • Mother’s respiration, circulation and Uterine muscular contraction force↑ • 20-30 s before of first stage of labor: 50% O2 and 50% N2O

18. Enflurane and Isoflurane • Light anesthesia: no inhibition • Deep anesthesia: mother: inhibition of uterine contraction, uterine bleeding fetus: disadvantage

19. Sevoflurane • Placental transfer is more rapid than halothane • Inhibition of uterine contraction: >halothane

20. Succinylcholine • Cholinesterase • Dose > 300 mg or single dose is justo major: still have placental transfer

21. Nondepolarizing Muscle Relaxants • Onset is quick, maintanence is short and placental transfer is least • Atracurium

22. Local anesthetics Factors: • Protein binding: • Molecular weight • Liposolubility • Catabolism in the placent

23. Local anesthetics • Procaine • Lidocaine • Bupivacaine • Ropivacaine

24. ANESTHESIA FOR CESAREAN SECTION Choice depends on : • the indications for the surgery • the degree of urgency • maternal status • desires of the patient

25. Spinal Anesthesia • Hyperbaric bupivacaine • Advantages : rapid onset, dense neural block, little risk of local anesthetic toxicity, minimal transfer to the fetus, infrequent failure. • Disadvantages : finite duration hypotension

26. Epidural Anesthesia • L 2～3 or L 1～2 • 1.5%～2% Lidocaine or 0.5% Ropivacaine • emergency cesarean section

27. Combined Spinal-Epidural Technique • Increased dramatically in popularity • Advantages : rapid onset supplemented at any time anesthetic dose↓ sacral nerves block is sufficient

28. General Anesthesia • rapid induction: obviate positive pressure ventilation oppress the cricoid cartilage • mainterance: light ansthesia • vomiting, backstreaming and aspiration: atropine, 0.5 mg, IM or glycopyrolate, 0.2 mg, IM

29. Supine hypotensive syndrome • Incidence: 2%～30% • Time: after 28 weeks, specially 32～36 weeks • Symptoms: ◆ hypotension, ◆ dizziness, ◆ nausea, ◆ chest distress, ◆ cold sweat, ◆ to yawn, ◆ pulse rate↑, ◆ pallescence • Mechanism • Prevent

30. High risk pregnancy • Emergency operation : late trimester of pregnancy gestational hypertension syndrom and eclampsia • Selective operation : hypertension cardiac disease diabetes multifetation

31. Placenta Previa and Placental Abruption • Preanesthtic preparation: blood coagulation function DIC sifting test acute renal failure • Principle: general anesthesia: active bleeding, hypovolemic shock, definite blood coagulation disfunction or DIC intraspinal anesthesia: condition of mother and fetus is okay • Management

32. degrees of abruptio placentae. A, Concealed hemorrhage. B, External hemorrhage. C, Complete placental separation.

33. Types of placenta previa.

34. Management of anesthesia • Announcements of the induction: difficult airway cricoid cartilage backstreaming and aspiration • Prepare to salvage the blood coagulation disfunction and the hemorrhoea. • Prevent the acute renal function failure: urine volume urea nitrogen and creatinine • Prevention and cure of DIC

35. Pregnancy-induced hypertension syndrome • Incidence: 10.3% • Cause of death: cerebrovascular accident, pneumonedema, liver necrosis • Pathophysiology: systemic arteriola systole, < 200µm, calcium ion, pachemia, hypovolemia→whole blood and plasma viscosity↑and hyperlipemia→microcirculation perfusion↓→intravascular coagulation

36. Pregnancy-induced hypertension syndrome complicating cardiac failure • Digitalization, diuresis, morphine, ↓BP. • Anesthesia: epidural anesthesia general anesthesia • Management: 毛花苷C -- maintenance dose: 0.2-0.4 mg furosemide (呋塞米）-- 20-40 mg oxygen maintain stabilization of the respiratory and circulatory system

37. Severe Pregnancy-induced hypertension syndrome • Preanesthesia prepare: ★ information of medication ★ magnesium sulfate ★ hypotensive drug ★ liquid intake and output volume • Anesthesia: termination of pregnancy epidural anesthesia: no blood coagulation disfunction, no DIC, no shock and no cataphora general anesthesia: safe of mother > fetus • Management:

38. HELLP syndrome • cardiac failure • cerebral hemorrhage • placental abruption • blood coagulation disfunction • haematolysis • hepatic enzyme↑ • thrombocytopenia • acute renal failure

39. Management 1 • trying stable anesthesia: ↓stress reaction: fentanyl avoid to use ketamine SBP: 140150 mmHg, DBP: about 90 mmHg ganglioplegic or nitroglycerin • maintain heart, kindey and lung function: • treatment of complication:

40. Management 2 • basic monitoring: ◆ECG ◆ SpO2 ◆ NIBP ◆ CVP ◆ urine volume ◆ blood gas analysis • prepare to salvage the neonatal asphyxia • ICU • postoperation analgesia

41. Multiple Births • pathophysiology: ◆abdominal aorta and inferior vena cava compression; ◆ fetal lung maturity; ◆ incidence of postpartum hemorrhage. • anesthesia: epidural anesthesia • management: ◆ addition of volume: colloid ◆ oxygen,prevention and cure of Supine hypotensive syndrome ◆ preparation of resuscitation of newborn

42. Neonatal asphyxia and emergency treatment

43. - The Apgar scoring system Score * Sign 0 1 2 Heart rate Absent Less than 100/min More than 100/min Respiratory effort Absent Slow, irregular Good, crying Color Blue, pale Body pink, extre mities blue (acrocyanosis) Completely pink Reflexirritability (response to Absent Grimace Cough, sneeze insertion of a nasal catheter) Muscle tone Limp Some flexion of extremities Active motion ASSESSMENT OF THE FETUS AT BIRTH Apgar score is a simple, useful guide

44. Apgar score • 1-minute score --- degree of asphyxia • 5-minute score --- prognosis • evaluated at 1 and 5 minutes. • should not wait until 1 minute has passed before initiating resuscitation. • normal: 7-10 mild asphyxia: 4-6 severe asphyxia: 0-3

45. Resuscitation of newborn • A ( Airway) • B ( Breathing) • C (Circulation) • D (Drug) • E (Evaluation)

46. Initial resuscitation • Incubation: 27～31℃ • Position: • Suctioning: mouth and nose • Stimulate: Complete it within 20s

47. Evaluation and further treatment • Evaluation: according to breath, heart rate and skin colour • Normal: stop resuscitation • No spontaneously brathing, HR<100/min: bag respirator • HR<80/min: closed cardiac massage; tracheal intubation, medication

48. Bag respirator • Maniphalanx pressurize • Tidal volume: 20～40ml • I : E = 1.5:1 • RP: 30～40/min • first twice: pressure – 30～40 cmH2O subsequently: pressure – 10～20 cmH2O

49. RESUSCITATION EQUIPMENT

50. Closed cardiac massage HR: 120/min Depth: 1～2cm