Anesthesia for Cesarean Section

Anesthesia for Cesarean Section

Common indications for cesarean section are listed in Table 41–4. The choice of anesthesia for cesarean section is determined by multiple factors, including the indication for operative delivery, its urgency, patient and obstetrician preferences, and the skills of the anesthetist. In a given country, cesarean section rates may vary as much as two-fold between institutions. In some countries, cesarean delivery is seen as preferable to labor and rates are much greater than those in the United States (which generally vary between 15% and 35% from hospital to hospital). In the United States most elective cesarean sections are performed under spinal anesthesia. Regional anesthesia has become the preferred technique becausegeneral anesthesia has been associated with a greater risk of maternal morbidity and mortality. Deaths associated with general anesthesia are gen-erally related to airway problems, such as inability to intubate, inability to ventilate, or aspiration pneumonitis, whereas deaths associated with regional anesthesia are generally related to exces-sive dermatomal spread of blockade or to local anesthetic toxicity.

Other advantages of regional anesthesia include (1) less neonatal exposure to potentially depressant

drugs, (2) a decreased risk of maternal pulmonary aspiration, (3) an awake mother at the birth of her child, and (4) the option of using spinal opioids for postoperative pain relief. Continuous epi-dural anesthesia allows better continuingcontrol over the sensory level than “single-shot” techniques. Conversely, spinal anesthesia has a more rapid, predictable onset; may produce a more dense (complete) block; and lacks the potential for serious systemic drug toxicity because of the smaller dose of local anesthetic employed. Regardless of the regional technique chosen, one must be prepared to administer a general anesthetic at any time during the procedure. Moreover, administration of a non-particulate antacid within 30 min of surgery should be considered.

General anesthesia offers (1) a very rapid and reliable onset, (2) control over the airway and venti-lation, (3) greater comfort for parturients who have morbid fears of needles or surgery, and (4) potentially less hypotension than regional anesthesia. General anesthesia also facilitates management in the event of severe hemorrhagic complications such as placentaaccreta. Its principal disadvantages are the risk of pulmonary aspiration, the potential inability to intu-bate or ventilate the patient, and drug-induced fetal depression. Present anesthetic techniques, however, limit the dose of intravenous agents such that fetal depression is usually not clinically significant with general anesthesia when delivery occurs within 10 min of induction of anesthesia. Regardless of the type of anesthesia, neonates delivered more than 3 min after uterine incision have lower Apgar scores and pH values.