Urgent Cesarean Section: What’s Good for Baby Is Good for Mommy?

Nathan J. Hess DO

Karen Hand MD

Nearly one fourth of all births in the United States today are via cesarean section, a dramatic increase from the 5.5% of births in 1970. A considerable number of these fall into the classification of urgent, nonelective cesarean. In some cases (i.e., massive maternal hemorrhage, dystocia), both the mother and the baby are in jeopardy. Quite commonly, however, there is nonreassuring fetal status without concomitant maternal distress. The parturient presenting for urgent cesarean section brings with her unique anesthetic challenges, and anesthesia-related complications in this setting can be associated with considerable maternal morbidity and mortality. Indeed, anesthesia is the seventh leading cause of maternal mortality in the United States.

PHYSIOLOGICAL CHANGES ASSOCIATED WITH PREGNANCY

There are numerous physiological changes that occur by the third trimester of pregnancy, many of which potentially make anesthesia more hazardous. The anesthesiologist must be familiar with the major physiological changes that occur with pregnancy and the potential anesthetic implications (Table 156.1).

INDICATIONS FOR URGENT CESAREAN SECTION

The anesthesiologist must be in close communication with the obstetrician in determining the indication and true urgency for cesarean section. A distinction must be made between urgent and emergent or stat section, as those in the former category may allow time for regional anesthesia, while those in the latter nearly always require general anesthesia in the absence of a functioning epidural catheter. Although each individual case must be considered in consultation with the obstetrician, those falling in the urgent but not emergent category generally include (a) variable decelerations with prompt recovery of fetal heart rate (FHR), (b) dystocia, (c) previous classic cesarean and active labor, (d) active genital herpes and ruptured membranes, (e) ruptured membranes and abnormal fetal presentation (i.e., transverse, breech, multiple gestation), and (f) rapidly deteriorating maternal illness (pre-eclampsia, cardiac, pulmonary). Conversely, those indications generally falling into the emergent or stat category include (a) prolonged fetal bradycardia or persistent late decelerations (rule of 60s = FHR <60/minute or deceleration lasting longer than 60 seconds), (b) massive maternal hemorrhage (placenta previa, placental abruption), (c) prolapsed umbilical cord, and (d) uterine rupture.

TABLE 156.1 PHYSIOLOGICAL CHANGES ASSOCIATED WITH PREGNANCY

SYSTEM	PHYSIOLOGICAL CHANGESAT TERM GESTATION(COMPARED WITHPREPREGNANT VALUES)	ANESTHETICIMPLICATIONS
Respiratory	30%-40% increase in oxygen consumption 20% decrease in FRC 45% increase in minute ventilation Increased airway edema and mucosal friability	Rapid development of hypoxemia during apnea, potentially difficult intubation
Cardiovascular	50% increase in cardiac output 20% decrease in SVR Possible aortocaval compression by gravid uterus 55% increase in plasma volume 45% increase in blood volume	Aortocaval compression→ decreased preload→ hypotension in supine parturient→ uteroplacental insufficiency
Gastrointestinal	Anatomic displacement of stomach cephalad and left	Increased risk for aspiration (Mendelson syndrome)
	Decreased lower esophageal sphincter tone
	Delayed gastric emptying?
	Increased gastric acid secretion?
Nervous	Increased sensitivity to IV anesthetics	Adjust doses accordingly
	MAC of volatile agents reduced 15%-40%
Miscellaneous	Engorged breasts Increased sensitivity to nondepolarizing MR	Difficult laryngoscope insertion, reduce dosages of NDMR
FRC, functional residual capacity; SVR, systemic vascular resistance; IV, intravenous; MAC, minimum alveolar concentration; MR, muscle relaxant; NDMR, non depolarizing muscle relaxant.