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Obstetric Anesthesia Department of anesthesiologyCui Xiao Guang,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,Respiratory System : increase in the respiratory minute volume and work of breathingGastrointestinal System : risk of incidence of aspirationendotracheal intubation: the risk Renal System : GFR rises 50% ; glycosuriaCentral Nervous System :sensitivity to anesthetics.,PHYSIOLOGIC CHANGES OF PREGNANCY 2,PLACENTAL TRANSFER OF ANESTHETIC DRUGS,Placenta transport : Simple diffusion Facilitated diffusion Active transport PinocytosisReadily cross : low molecular weights, high lipid solubility , non-ionized Approximately 50% of the umbilical venous blood bypasses the liver.,Morphine,Placental transfer is rapidMother: uterus reactiveness orthostatic hypotension nausea vomiting delayed gastric emptyingFetus: respiratory depression,Pethidine,Most commonly used during labor intramuscular dose : 50 -100 mg Time of IM: before expulsion 1 h or 4 huterine contraction, frequency and intension ,Fentanyl Alfentanil Sufentanil,Placental transfer is rapid Low dose: 10 -25 g fentanyl or 5-10 g sufentanil in subarachnoid space PCEA: low dose of fentanyl and 0.1%-0.3% ropivacaine,Tramadol,Placental transfer No inhibiting uterine contraction No Respiratory depression,Diazepam,Readily cross the placenta Half-lives: 48 hours Problems: sedation, hypotonia, cyanosis, impaired metabolic responses to stress.,Midazolam,Plasma protein binding: 94% Respiratory depression: depended on dose 0.075 mg/kg no problem 0.15 mg/kg different degree,Chlorderazin,Preeclampsia and eclampsia IM：12.5 25 mg Overdose: central inhibition,Promethazine,Prevent emesis Appears in fetal blood within 1 to 2 minutes after intravenous injection in the mother Reaches equilibrium within 15 minutes,Droperidol,Pregnant woman: 慎用Apgar score ,Thiopental sodium,Neonatus sleep: little Premature and intrauterine embarrass: carefully using,Ketamine,High doses (greater than 2 mg/kg) may cause low Apgar scores and abnormalities in neonatal muscle toneLabor pains of uterine contractionUterine muscular tension and contraction forceContraindication: psychosis, gestational hypertension syndrome or preeclampsia, metrorrhexis,Propofol,Recommendation: induction: 2.5 mg/kg maintenance: 2.5-5.0 mg/kg/h Discontinue gravidity only,N2O,Placental transfer is rapid Mothers respiration, circulation and Uterine muscular contraction force 20-30 s before of first stage of labor: 50% O2 and 50% N2O, maximumhalothane,Succinylcholine,Cholinesterase: normal doseno placental transfer Dose 300 mg or single dose is larger: still have placental transfer,Nondepolarizing Muscle Relaxants,Onset is quick, maintanence is short and placental transfer is leastAtracurium: 0.3 mg/kg,Local anesthetics,Factors:Protein binding: Molecular weightLiposolubility Catabolism in the placent,Local anesthetics,Procaine Lidocaine Bupivacaine Ropivacaine,ANESTHESIA FOR CESAREAN SECTION,Choice depends on : the indications for the surgery the degree of urgency maternal status desires of the patient,Spinal Anesthesia,Hyperbaric bupivacaine Advantages : rapid onset, little risk of local anesthetic toxicity, minimal transfer to the fetus, infrequent failure. Disadvantages : finite duration hypotension headache,Epidural Anesthesia,L 23 or L 12 1.5%2% Lidocaine or 0.5% Ropivacaine emergency cesarean section,Combined Spinal-Epidural Technique,Increased dramatically in popularity Advantages : rapid onset supplemented at any time anesthetic dose sacral nerves block is sufficient,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,Supine hypotensive syndrome,Incidence: 2%30% Time: after 28 weeks, specially 3236 weeks Symptoms: hypotension, dizziness, nausea, chest distress, cold sweat, to yawn, pulse rate, pallescenceMechanismPrevent,High risk pregnancy,Emergency operation : late trimester of pregnancy: hemorrhage gestational hypertension syndrom and eclampsia Selective operation : hypertension cardiac disease diabetes multifetation,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,degrees of abruptio placentae. A, Concealed hemorrhage. B, External hemorrhage. C, Complete placental separation.,Types of placenta previa.,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,Pregnancy-induced hypertension syndrome,Incidence: 10.3% Cause of death: cerebrovascular accident, pneumonedema, liver necrosis Pathophysiology: systemic arteriola systole, fetus Management:,HELLP syndrome,cardiac failure cerebral hemorrhage placental abruption blood coagulation disfunction haematolysis hepatic enzyme thrombocytopenia acute renal failure,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:,Management 2,basic monitoring: ECG SpO2 NIBP CVP urine volume blood gas analysis prepare to salvage the neonatal asphyxia ICU postoperation analgesia,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,Neonatal asphyxia and emergency treatment,ASSESSMENT OF THE FETUS AT BIRTH,Apgar score is a simple, useful guide,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,Resuscitation of newborn,A ( Airway) B ( Breathing) C (Circulation) D (Drug) E (Evaluation),Initial resuscitation,Incubation: 2731 Position: Suctioning: mouth and nose Stimulate:,Complete it within 20s,Evaluation and further treatment,Evaluation: according to breath, heart rate and skin colour Normal: stop resuscitation No spontaneously brathing, HR100/min: bag respirator HR80/min: closed cardiac massage; tracheal intubation, medication,Bag respirator,Maniphalanx pressurize Tidal volume: 2040ml I : E = 1.5:1 RP: 3040/min first twice: pressure 3040 cmH2O subsequently: pressure 1020 cmH2O,RESUSCITATION EQUIPMENT,Closed cardiac massage,HR: 120/minDepth: 12cm,RESUSCITATION DRUGS,30s after the closed cardiac massage, still cant recovery : drug Epinephrine: 0.10.2mg/kg, intratracheal drop in,Hypovolemia causes,umbilical cord was clamped and cut earlier intrauterine asphyxia placental abruption hemorrhage too much: antepartum or intrapartum,Detection of Hypovolemia,arterial blood pressure and CVP pale skin poor capillary refill extremities are cold pulses are weak or absent,Treatment of Hypovolemia,intravascul