Obstetrics Anesthesia

Educational Objectives

We have well-defined objectives for you to accomplish during your time on the labor floor. These objectives are accomplished through clinical experience, bedside teaching, journal club, and formal lectures.

1. Maternal physiologic changes of pregnancy.

A. Maternal cardiovascular adaptation

1. Intravascular volume change
2. Changes in cardiac output
a. antepartum
b. peripartum (during labor)
c. postpartum
3. Aortocaval compression/supine hypotension
a. normal compensatory mechanisms
b. potential effects of regional anesthesia
4. Potential effects of cardiovascular changes on the rate of an intravenous or inhalation induction of general anesthesia

B. Determinants of uterine blood flow, including the effects of regional and general anesthesia on uterine blood flow

C. Respiratory changes

1. Changes in lung volumes and capacities
2. Change in normal values of an arterial blood gas
3. Why an inhalation induction may be faster
4. Effect of pregnancy on the rate of arterial oxygen desaturation during apnea

D. Gastrointestinal changes

1. Changes in gastric pH and volume
2. Mendelson's syndrome
3. Aspiration prophylaxis
a. particulate vs. nonparticulate antacid
b. H2 blockers
c. use of metoclopramide
4. Changes in liver function
a. drug metabolism
b. serum cholinesterase levels
c. albumen production
d. production of clotting factors
e. production of thyroid binding globulinz

E. Renal changes, including the change in GFR

F. Endocrine changes

1. Thyroid function
2. Glucose metabolism
3. Diabetes mellitus
a. white classification of diabetes
b. insulin treatment
c. potential effects of maternal hyperglycemia on the newborn, including potential complications of maternal administration of glucose-containing intravenous solutions

2. Preoperative evaluation of the obstetric patient.

A. History and physical examination

1. A thorough history and physical exam must be performed on all patients prior to the administration of anesthesia, including maternal blood pressure
2. Implication of maternal hypertension
3. Potential airway changes associated with pregnancy
4. How to determine which laboratory tests are indicated, and interpret the results

B. Pre-anesthetic fetal evaluation

1. Significance of fetal abnormalities on the anesthetic management of the parturient
2. Fetal heart rate monitoring
a. fetal heart rate variability
b. how to identify early vs. late vs. variable decelerations, and the significance of each
3. Monitoring uterine contractions
a. normal contraction pattern
b. significance of uterine hyperstimulation
4. Fetal acid-base status
a. normal values for a fetal scalp blood pH
b. significance of a low fetal scalp pH

3. Special problems encountered in obstetrical patients.

A. Potential difficult airway

B. Increased risk of aspiration

C. Hypertensive disorders of pregnancy, including their differential diagnosis

1. Define chronic hypertension, gestational hypertension, preeclampsia, and preeclampsia superimposed on chronic hypertension
2. Potential etiology of preeclampsia
3. Maternal physiologic alterations induced by preeclampsia
4. Distinguish between preeclampsia and eclampsia
a. seizure prophylaxis with magnesium sulfate
b. the toxic effects of magnesium therapy and the maternal serum levels of magnesium associated with each
5. Treatment of hypertension during preeclampsia
6. Potential risks of and benefits of epidural analgesia in preeclamptic patients
7. Potential risks of the induction of general anesthesia in the preeclamptic patients.

D. Obstetrical hemorrhage

1. Pregnancy-induced changes in coagulation
2. Disseminated intravascular coagulation
3. Potential hematologic alterations induced by:
a. abruptio placenta
b. preeclampsia
c. fetal death-in-utero
d. amniotic fluid embolus
4. Management of DIC

E. Risks and benefits of epidural anesthesia in parturients with valvular heart disease

1. Mitral stenosis
2. Aortic stenosis
3. Mitral regurgitation
4. Aortic regurgitation
5. IHSS

F. Advantages and disadvantages of epidural anesthesia in the parturient with severe asthma

G. Management of the parturient with a neurologic disorder

1. Seizure disorder
2. Multiple sclerosis
3. Myasthenia gravis
4. Arterio-venous malformation
5. Spinal cord injury
6. Degenerative disc disease
7. Scoliosis: with or without corrective surgery
8. Peripheral neuropathy

H. Significance of preterm labor

1. Implications of regional and general anesthesia for the preterm fetus
2. Tocolytic agents
a. the most commonly used
b. their pharmacology
c. side effects
i. effects on maternal glucose metabolism
ii. effect on serum potassium levels
iii. cardiovascular effects
1) maternal heart rate
2) maternal cardiac ischemia
3) pulmonary edema
iv. anesthetic implications of maternal administration of tocolytic agents

I. Neonatal resuscitation

1. Changes in neonatal circulation to allow the fetus to adapt to extra-uterine life
a. Changes in the pulmonary and systemic circulation at birth
i. Cause of physiologic closure of the ductus arteriosus and the foramen ovale
ii. Significance of failure of physiologic closure of these shunts
iii. What factors may predispose the fetus to close these shunts
b. Factors stimulating the initiation of respiration in the newborn
c. Apgar Score
i. initial assessment of the newborn
ii. management of an infant that demonstrates respiratory depression and bradycardia at birth
iii. indications for intubation of the newborn infant
iv. indications for chest compressions in the depressed infant
v. use of epinephrine for newborn resuscitation and the possible routes of administration
vi. indications for volume replacement in the depressed neonate
d. Management of the neonate stained with meconium
i. when intubation is needed
ii. when only suctioning is recommended

4. Anesthesia for labor and delivery.

A. Non-pharmacologic techniques: advantages and disadvantages</>

1. Psycho prophylaxis (prepared childbirth education)
2. TENS
3. Acupuncture
4. Self-hypnosis

B. Parenteral narcotic analgesia

1. Advantages and disadvantages of IV narcotic administration
a. meperidine
i. risk of seizure
ii. metabolite normeperidine
b. fentanyl
c. morphine sulfate
d. agonist/antagonist narcotics: butorphanol and nalbuphene
2. IV PCA administered narcotics for labor analgesia

C. Inhalation analgesia

1. N2O/O2 mixture
2. Inhalation of halogenated agents

D. Epidural and subarachnoid labor analgesia

1. Advantages and disadvantages of neuraxial labor analgesia
a. epidural
b. spinal
c. combined spinal/epidural
2. Site of action of local anesthetics
a. epidural space
b. subarachnoid space
3. Site of action of narcotics
a. epidural space
b. subarachnoid space
4. Pharmacology of the anesthetics when administered into either the epidural or subarachnoid space
a. bupivacaine
b. levobupivacaine
c. ropivacaine
d. chloroprocaine
e. meperidine (discuss the local anesthetic effects)
f. fentanyl
g. sufentanil
5. Local anesthetic toxicity
a. signs and symptoms of an intravenous injection of local anesthetic
b. relative cardiac toxicity of local anesthetics, and the treatment
6. Complications of an incidental dural puncture during placement of an epidural
a. how to recognize a high spinal vs. total spinal anesthetic
i. etiology of respiratory arrest with a total spinal anesthetic
ii. why the pupil will be dilated after total spinal anesthesia
b. diagnosis and management of dural puncture headache
i. complications of epidural blood patch
ii. prophylactic epidural blood patch
7. Risk of neurologic injury after placement of a regional anesthetic.
a. backache after regional anesthesia
b. nerve root injury after epidural or spinal placement
c. spinal cord injury after epidural or spinal anesthesia

5. Anesthesia for Cesarean Section.

A. Advantages and disadvantages of epidural, spinal or general anesthesia for cesarean section

B. Local anesthetics, concentrations and doses, used for either epidural or spinal anesthesia for cesarean section

C. Preparation of the pregnant patient for general anesthesia

1. Impact of the GI changes in pregnancy on the risk of maternal aspiration of gastric contents after the induction of general anesthesia
2. Technique of rapid sequence induction
a. why this is necessary in the term pregnant patient
b. rate of oxygen desaturation during a rapid sequence induction of GA in the pregnant patient
3. Induction of general anesthesia
a. advantages and disadvantages of specific induction agents
i. Etomidate
ii. Pentothal
iii. Propofol
iv. Ketamine
b. induction dose of each
4. Effects of regional vs. general anesthesia on uterine blood flow
5. Appropriate anesthetic choices for emergency cesarean section, situations
a. non-reassuring fetal heart rate tracing
b. maternal hemorrhage
c. double set up

D. Techniques of postoperative analgesia after cesarean section

1. Parenteral narcotics -- intermittent dosage or IV PCA
2. Epidural narcotics: with or without local anesthetics
a. preservative-free morphine
b. epidural infusion of narcotics/local anesthetic solutions
3. Subarachnoid narcotics
a. preservative-free morphine
b. other narcotics

6. Equipment necessary to care for the peripartum patient.

7. Care for the pregnant patient during the peripartum and/or perisurgical period.

A. Perform an appropriate history and physical exam and order lab investigations when indicated

B. Make an appropriate anesthetic plan

1. Labor analgesia
a. contraindications to the placement of a neuraxial block
b. appropriate times to administer:
i. epidural labor analgesia
ii. spinal labor analgesia
iii. combined epidural-spinal analgesia
iv. intravenous narcotics
c. appropriate maternal and fetal monitoring after placement of an epidural and/or spinal labor analgesic
2. General anesthesia
a. establish appropriate monitoring prior to the induction of general anesthesia
b. choose an appropriate induction technique
3. Complications of anesthetic interventions, such as:
a. maternal hypotension
b. high or total spinal
c. failed or difficult intubation
d. inadvertent dural puncture
e. management of local anesthetic overdose or intravascular injection
i. local anesthetic induced seizure
ii. local anesthetic induced cardiac toxicity
iii. inadequate anesthesia or analgesia

C. Provide care for the newborn if needed, including neonatal resuscitation

Formal lectures administered on a monthly basis

  1. Physiologic adaptation to pregnancy
  2. Neonatal resuscitation
  3. Anesthesia for toxemia
  4. Obstetric hemorrhage
  5. Complications of Obstetric Anesthesia
  6. Fetal heart rate monitoring
  7. Management of postdural puncture headache
  8. Labor analgesic techniques: epidural vs. combined spinal-epidural
  9. Local anesthetics