Anesthesia for Obstetrics

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• Anesthesia for Obstetrics
• Department of anesthesiology
• Cui Xiao Guang

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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

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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.

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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.

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Morphine

• Placental transfer is rapid
• Mother uterus reactiveness?
• orthostatic hypotension
• nausea
• vomiting
• delayed gastric emptying
• Fetus respiratory depression

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Pethidine

• Most commonly used during labor
• intramuscular dose 50 -100 mg
• Time of IM before expulsion 1 h or 4 h
• uterine contraction, frequency and intension ?

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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

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Tramadol

• Placental transfer
• No inhibiting uterine contraction
• No Respiratory depression

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Diazepam

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

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Midazolam

• Plasma protein binding 94
• Respiratory depression depended on dose
• 0.075 mg/kg no problem
• 0.15 mg/kg different degree

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Chlorderazin

• Preeclampsia and eclampsia
• IM12.5 25 mg
• Overdose central inhibition

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Promethazine

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

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Droperidol

• Pregnant woman ??
• Apgar score ?

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Thiopental sodium

• Neonatus sleep little
• Premature and intrauterine embarrass
  carefully using

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Ketamine

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

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Propofol

• Recommendation
• induction lt2.5 mg/kg
• maintenance 2.5-5.0 mg/kg
• Discontinue gravidity only

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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

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Enflurane and Isoflurane

• Light anesthesia no inhibition
• Deep anesthesia
• mother inhibition of uterine
  contraction,
• uterine bleeding
• fetus disadvantage

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Sevoflurane

• Placental transfer is more rapid than halothane
• Inhibition of uterine contraction gthalothane

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Succinylcholine

• Cholinesterase
• Dose gt 300 mg or single dose is justo major
  still have placental transfer

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Nondepolarizing Muscle Relaxants

• Onset is quick, maintanence is short and
  placental transfer is least
• Atracurium

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Local anesthetics

• Factors
• Protein binding
• Molecular weight
• Liposolubility
• Catabolism in the placent

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Local anesthetics

• Procaine
• Lidocaine
• Bupivacaine
• Ropivacaine

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ANESTHESIA FOR CESAREAN SECTION

• Choice depends on
• the indications for the surgery
• the degree of urgency
• maternal status
• desires of the patient

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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

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Epidural Anesthesia

• L 23 or L 12
• 1.52 Lidocaine or 0.5 Ropivacaine
• emergency cesarean section

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Combined Spinal-Epidural Technique

• Increased dramatically in popularity
• Advantages
• rapid onset
• supplemented at any time
• anesthetic dose?
• sacral nerves block is sufficient

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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

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Supine hypotensive syndrome

• Incidence 230
• Time after 28 weeks, specially 3236 weeks
• Symptoms
• ? hypotension, ? dizziness,
• ? nausea, ? chest distress,
• ? cold sweat, ? to yawn,
• ? pulse rate?, ? pallescence
• Mechanism
• Prevent

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High risk pregnancy

• Emergency operation
• late trimester of pregnancy
• gestational hypertension syndrom and
  eclampsia
• Selective operation
• hypertension
• cardiac disease
• diabetes
• multifetation

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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

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degrees of abruptio placentae. A, Concealed
hemorrhage. B, External hemorrhage. C, Complete
placental separation.
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Types of
placenta previa.
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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

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Pregnancy-induced hypertension syndrome

• Incidence 10.3
• Cause of death
• cerebrovascular accident,
• pneumonedema,
• liver necrosis
• Pathophysiology
• systemic arteriola systole, lt 200 µm,
• calcium ion,
• pachemia, hypovolemia?whole blood and
  plasma viscosity?and hyperlipemia?microcirculati
  on perfusion??intravascular coagulation

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Pregnancy-induced hypertension syndrome
complicating cardiac failure

• Digitalization, diuresis, morphine, ?BP.
• Anesthesia
• epidural anesthesia
• general anesthesia
• Management
• ???C -- maintenance dose 0.2-0.4 mg
• furosemide (???)-- 20-40 mg
• oxygen
• maintain stabilization of the respiratory
  and circulatory system

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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 gt
  fetus
• Management

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HELLP syndrome

• cardiac failure
• cerebral hemorrhage
• placental abruption
• blood coagulation disfunction
• haematolysis
• hepatic enzyme?
• thrombocytopenia
• acute renal failure

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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

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Management 2

• basic monitoring
• ?ECG ? SpO2
• ? NIBP ? CVP
• ? urine volume ? blood gas analysis
• prepare to salvage the neonatal asphyxia
• ICU
• postoperation analgesia

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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

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Neonatal asphyxia and emergency treatment
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ASSESSMENT OF THE FETUS AT BIRTH

• Apgar score is a simple, useful guide

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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

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Resuscitation of newborn

• A ( Airway)
• B ( Breathing)
• C (Circulation)
• D (Drug)
• E (Evaluation)

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Initial resuscitation

• Incubation 2731?
• Position
• Suctioning mouth and nose
• Stimulate

Complete it within 20s
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Evaluation and further treatment

• Evaluation according to breath, heart rate and
  skin colour
• Normal stop resuscitation
• No spontaneously brathing, HRlt100/min bag
  respirator
• HRlt80/min closed cardiac massage tracheal
  intubation, medication

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Bag respirator

• Maniphalanx pressurize
• Tidal volume 2040ml
• I E 1.51
• RP 3040/min
• first twice pressure 3040 cmH2O
• subsequently pressure 1020 cmH2O

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RESUSCITATION EQUIPMENT
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Closed cardiac massage
HR 120/min Depth 12cm
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RESUSCITATION DRUGS

• 30s after the closed cardiac massage, still
  dont recovery drug
• Epinephrine 0.10.2mg/kg,
  intratracheal drop in

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Hypovolemia causes

• umbilical cord was clamped and cut earlier
• intrauterine asphyxia
• placental abruption
• hemorrhage too much
• antepartum or intrapartum

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Detection of Hypovolemia

• arterial blood pressure and CVP ?
• pale skin
• poor capillary refill
• extremities are cold
• pulses are weak or absent

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Treatment of Hypovolemia

• intravascular volume expansion
• blood, plasma ,crystalloid , Albumin
• 10 mL/kg of normal saline, 1 to 2 g/kg of 25
  albumin, or 10 mL/kg of plasma.
• Care must be taken

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Correction of Acidosis

• Respiratory acidosis is corrected by controlling
  ventilation
• Metabolic acidosis is corrected by infusing
  sodium bicarbonate.
• Requisite amount of sodium bicarbonate(mmol)
• 0.6BW(kg)(normal BE-present BE)/4
• sodium bicarbonate lt1 mmol/kg/min
• Sodium bicarbonate should not be infused -unless
  ventilation is adequate.

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Monitoring After resuscitation

• temperature
• breath
• heart rate
• blood pressure
• urine volume

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Gynecologic anesthesia

• Special position
• head down and lithotomy position
• Old age comorbidities
• Emergency case exfetation, ovarian cyst
  intortion, perineal position trauma, uterine
  perforation
• More other selective operation
• Hysteroscope and Laparoscopic Surgery