Anesthesiology Case Study #2
Choice of Anesthesia During Cesarean Section
Prepared by Melissa Pujazon (MS4, UT Southwestern Medical School)

PART I: The Case Study

April Walters is a 28 year old G3P2 Caucasian female with no pertinent past medical history who presents to the hospital in preparation for her scheduled cesarean section to be performed tomorrow morning at 8 AM. Her vital signs and lab work are all normal. April is having a cesarean section because she had two cesarean sections for her past pregnancies. She states she had significant pain with her last two c-sections (both performed under epidural anesthesia at another hospital) and is requesting general anesthesia for this c-section. The frantic patient proclaims "Just knock me out - I don't care if I don't "experience" the birth of my child - all I care about is that I don't experience pain. I'll have many years to bond with my baby, and I am sure I'll like him a lot more if my cesarean is painless."

Would you proceed with general anesthesia or would you offer regional anesthesia to this patient? When is general anesthesia indicated for a cesarean section? What are the potential problems that April may encounter if she undergoes general anesthesia? What are the potential effects to the neonate from the general anesthesia?

PART II: Five Clinical Learning Points

1) Epidural and spinal anesthetics are generally preferred for a non-emergent cesarean section.

    The anesthetic for a patient undergoing a cesarean section is selected based on the reason for the operation, the degree of urgency, and the desires of the patient. The anesthesiologist must choose the method that is believed to be safest and most comfortable for the mother and least depressant to the newborn and that provides the optimal working conditions for the obstetrician. Survey data from 1992 from the United States reveal that more than 84 percent of cesarean deliveries are performed with regional anesthesia (spinal, 40%; epidural, 44%; general, 17%).1

    If a patient has not already had an epidural or spinal anesthesia for labor, or this is a non-emergent cesarean section, the patient will most likely be given an epidural or spinal anesthetic. If there is a reason that the patient can't have regional anesthesia or it is an emergency the patient will be given a general anesthetic

 

2) There are unique advantages and disadvantages involved with epidural and spinal anesthetics.

    The benefits of regional (epidural or spinal) anesthesia are many and include an awake mother who is able to participate in the birth of her baby, minimal newborn depression, and no risks associated with general anesthesia (such as aspiration pneumonia or failed intubation.)

    Spinal anesthesia has the advantage of simple administration, small dosage requirements, a low failure rate and rapid anesthesia from the waist to the toes. Many patients report that anesthesia is more "uniformly distributed" compared to epidural anesthesia.

    The disadvantages of spinal anesthesia include a higher incidence of hypotension (compared to epidural anesthesia), post-spinal headache and a finite duration of anesthesia.

    Epidural anesthesia has the advantage of being more flexible than spinal anesthesia.

    Patients with an epidural catheter in place for labor can have the block extended to provide suitable anesthesia for cesarean delivery. An epidural catheter should be placed early and tested for function in patients at risk for cesarean delivery. Flexibility for the duration of anesthesia for surgery and control of block height are other advantages of epidural anesthesia.2 It is notable that despite some decrease in blood pressure during the induction of a surgical level of epidural anesthesia, remarkable stability in maternal cardiac output has been reported.3

    With either spinal or epidural anesthesia, patients undergoing cesarean delivery are most comfortable when regional block height is at least T4.

 

3) General anesthesia can be used for a cesarean section in situations involving fetal compromise, maternal hemorrhage, overt coagulopathy or patient preference.

    The advantages of general anesthesia include rapid induction, less associated hypotension and cardiovascular instability, and better control of the airway and ventilation.

 

4) Pulmonary aspiration and failed intubation are two of the most severe potential problems associated with general anesthesia.

    Potential problems during general anesthesia include pulmonary aspiration of gastric contents, failed intubation, maternal hyperventilation, neonatal depression, and uterine atony. Routine administration of antacids and histamine blockers before induction raises gastric PH and is prophylactic treatment for pulmonary aspiration.

    Difficulties with endotracheal intubation occur more commonly in obstetric patients than in general surgical patients. A report of anesthesia-related maternal mortality (1979-1990) found that most (106/129; 82%) maternal deaths during anesthesia occur during cesarean delivery. Further, 67 (52%) occurred during general anesthesia, and airway problems accounted for 73 percent of general anesthesia-related deaths.4

 

5) General anesthesia is associated with neonatal depression, but this effect can be reduced by limiting the time of general anesthesia.

    The general anesthetics (nitrous oxide and volatile anesthetics) used for cesarean delivery cross the placenta and can cause neonatal depression.1 Neonatal depression is mild if the time from anesthesia to delivery is less than 10 minutes. It would be best to delay induction of anesthesia until the patient is prepared and draped and the obstetrician is ready to start. According to Miller's Anesthesia:

    Retrospective studies associate neonatal depression with the use of general anesthesia; however, these reports are flawed by selection bias. Neonates born of mothers receiving general anesthesia may be more depressed and acidotic and require increased resuscitation not because of general anesthesia per se but because of the reason that general anesthesia was chosen (e.g., severe fetal compromise, maternal hemorrhage). Comparisons of neonatal outcome after elective cesarean delivery with either general or epidural anesthesia do not show important differences in neonatal outcome.

REFERENCES

1. Miller: Anesthesia, 5th Edition. Churchill Livingston, 2000.
2. Hawkins JL, Gibbs CP, Orleans M et al: Obstetric anesthesia workforce survey, 1981 versus 1992. Anesthesiology 87:135, 1997.
3. Robson SC, Boys RJ, Rodeck C et al: Maternal and fetal haemodynamic effects of spinal and extradural anaesthesia for elective caesarean section. British Journal of Anesthesiology 68:54, 1992.
4. Hawkins JL, Koonin LM, Palmer SK et al: Anesthesia-related deaths during obstetric delivery in the United States, 1979-1990. Anesthesiology 86:77, 1997.