LESSONS LEARNED IN OBSTETRIC ANESTHESIA
| THE PREGNANT PATIENT FOR NONOBSTETRIC SURGERY —Joy L. Hawkins, MD, Professor of Anesthesiology
and Director, Obstetric Anesthesia, University of Colorado School of Medicine, Denver
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| Introduction: anesthesia for pregnant patient undergoing nonobstetric surgery “is an agonizing thing”; routine
case suddenly more anxiety-provoking after discovering pregnancy; lay public and clinicians unsure
what to do with available information
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| Patients requiring preoperative pregnancy testing: ambulatory surgery patient undergoing knee arthroscopy;
50% of pregnancies in United States unplanned; 1-yr study found 7 of 2000 women of child-bearing age (12
to 50 yr) presenting to ambulatory surgery center pregnant; women denied being pregnant before testing; all 7
elected to cancel surgery; estimated cost to diagnose one pregnancy ≈$3000; study from pediatric hospital
found 2.4% of children ≥16 yr of age had positive pregnancy test, and overall positive pregnancy test rate
1.3%; concluded that pregnancy testing should be mandatory in girls ≥15 yr of age; specific written consent
unnecessary; proper notification significant (“giving someone the results of a positive pregnancy test is not an
innocuous social consideration”); before establishing similar program, consider cost of testing (urine vs
blood), whether to test without consent, whether to inform parents of minor child about positive test, what to
do following positive pregnancy test (eg, cancel case), and how to change anesthetic management (literature
inadequate to let patient or practitioner know whether anesthesia has harmful effects; pregnancy testing may
be offered to women of childbearing age if it will change management)
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| Drugs to avoid in pregnant patients: nitrous oxide and benzodiazepines; patient at 12 wk gestation requests
general anesthesia (GA) for cervical cerclage placement; American College of Obstetricians and Gynecologists
(ACOG) does not consider anesthetic medications problematic; limited information available; nitrous
oxide—animal study from 1980 found more abortions and more congenital anomalies in group receiving nitrous
oxide; appears that teratogenic effects seen in animals relate more to uterine artery vasoconstriction and
decreased uterine blood flow (BF) to fetus than to biochemical effects; introducing folate to protect pathway
and interrupt problem does not make any difference; adverse human effects never shown with use of nitrous
oxide; benzodiazepines—in 1970s, 2 studies showed association between maternal exposure to benzodiazepines
and cleft lip and/or cleft palate in fetus; later studies did not show same connections; study in British
Medical Journal looked at several cohort studies and did not find increased risk for major malformations when
exposed to benzodiazepines; package insert for midazolam indicates increased risk for congenital malformations
associated with use of benzodiazepines suggested in several studies, and patient should be apprised of
potential hazard to fetus
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| Fetal monitoring: examples include elective cholecystectomy in woman with recurrent cholelithiasis, emergency
femoral thrombectomy in woman at 31 wk gestation, and series of electroconvulsive therapy (ECT)
sessions in woman between 17 and 19 wk gestation; normal intraoperative monitors include blood pressure
(BP), oxygenation, and ventilation; blood glucose important during longer case; continuous fetal monitoring
possible if >24 wk gestation; continuous monitoring not possible if <24 wk gestation (but consider preoperatively,
postoperatively, and in holding area); fetal monitoring medical issue, not medicolegal issue; ensure
that intrauterine environment as optimized as possible (especially during regional anesthesia [RA]); fetal
monitoring inexact science; following deceleration, perform series of maneuvers to optimize uterine BF (eg,
increase maternal FIO2 , increase BP) and document efforts
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| Surgery in specialty hospital without labor-and-delivery: no fetal monitoring or obstetric coverage (ie, incapable
of performing cesarean delivery; neonatologists not available to resuscitate baby that might be delivered
and have problem); ACOG Committee Opinion on Nonobstetric Surgery During Pregnancy has no
outcome data showing any difference for monitoring fetus or altering anesthetic technique; no specific recommendations
can be made; important that obstetricians know about woman; if fetal monitoring used, it must be
individualized (based on gestational age, type of surgery, and availability of facilities); obstetrics, anesthesia,
and surgery must coordinate care
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| Ex-utero intrapartum treatment (EXIT) procedure: used for fetus with impingement of airway; obstetrician
can antenatally document problem that might have been fatal at birth; performed at term in cesarean delivery
suite under GA; patient should be deeply anesthetized and uterus relaxed; use high-concentration volatile
agents and high doses of narcotics; fetus anesthetized when delivered; obstetrician makes uterine incision and
removes head and one arm from uterus (remainder of body and umbilical cord remains in uterus); place fetal
pulse oximeter; administer intramuscular (IM) drugs if neonate inadequately anesthetized; clinician at head of
bed manages airway; once airway secure, may give surfactant if premature; complete as with normal cesarean
delivery
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| Anesthetic to protect fetal brain from neuronal death: healthy parturient requires emergency appendectomy
and questions anesthesia provider about effect of general anesthetic on developing fetal brain; current anesthetics
either increase inhibition by stimulating γ-aminobutyric acid (GABA) receptors (eg, benzodiazepines,
induction agents, volatile anesthetics) or suppress excitation by depressing N-methyl-D-aspartate (NMDA)
receptors (eg, nitrous oxide, ketamine); in animal studies, blocking NMDA receptors triggers widespread cell
death in developing brain during late fetal and early neonatal growth; recent article recommends avoiding exposing
unborn child to general anesthetics whenever possible, even if necessary to delay surgery until after
delivery; most animal data show that, although hemodynamics and oxygenation normal in fetus, acute respiratory
acidosis develops with laparoscopy during pregnancy; additional study shows significant hemodynamic
and oxygenation effects during 20 to 22 wk gestation (eg, decreased uterine BF, fetal acidosis and
decreased O2 content, fetal bradycardia, hypotension); remained 2 hr after insufflation
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| MATERNAL MORTALITY: AVOIDING DISASTERS —Samuel C. Hughes, MD, Professor of Clinical Anesthesia,
University of California, San Francisco, School of Medicine, and Director, Obstetrical Anesthesia, San
Francisco General Hospital
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| Rates: in 1900, maternal mortality rate in United States 900 deaths/100,000 live births; dramatic changes occurred
in late 1930s through 1940s; not much change since that time; in 1996, mortality rates in sub-Saharan
Africa similar to numbers from United States in 1900; also significant problem in Central Asia; much lower
rates in Europe (in Denmark, only 5 maternal deaths/ 100,000); US rates declining from 1967 to 1995, “but
disturbingly a plateau” (current figures seem stable to slightly increasing; may be due to better reporting)
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| Causes: include embolism (amniotic and thrombotic), hemorrhage (including ectopic), hypertensive disease,
infection, cardiomyopathy, and anesthesia (declining percentage); numbers from United Kingdom suggest
similar concerns (include thrombosis, thromboembolism, and hemorrhage); anesthesia providers often think
only of labor-and-delivery area when considering maternal mortality, but other areas important, including
managing or assisting with ectopic pregnancy, stillbirth, abortion (miscarriage or planned), live birth, and molar
pregnancy; leading causes of maternal deaths from pregnancy ending in abortion include infection, hemorrhage,
embolism, and anesthesia; recommendations from United Kingdom state that when hemorrhagic shock
follows rupture of ectopic pregnancy, patient should be transferred to operating room immediately (do not
wait to resuscitate); obstetric colleagues should consider this diagnosis in any woman of reproductive age
with abdominal complaints
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| Factors relating to maternal risk: include increasing age (more dramatic in black population; risk greater in Hispanic
than in whites), no prenatal care, and education <12 yr
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| Pregnancy-related maternal mortality in United States: Berg study from early-to-mid 1980s through 1997
found anesthesia deaths continued to decline; other areas of decline include hemorrhage and embolism; increase
seen in cardiomyopathy; anesthesia-related maternal mortality showed decline to 1.7 per million
through 1990 in United States, and similar results in United Kingdom; Hawkins study comparing GA and RA
(1979-1981 through 1988-1990); fewer general anesthetics currently performed, yet deaths remain constant;
epidural anesthesia increasing (61% of all patients), yet deaths continue to decline; 82% of deaths occur during
cesarean delivery; deaths with GA related to airway problems (including aspiration, intubation problems,
and inadequate ventilation) and cardiac arrest; deaths with RA related to local anesthetic toxicity and high
spinal; ACOG recognizes that failed intubation and pulmonary aspiration remain leading causes of maternal
mortality; some cases related to obesity (causes increases in preeclampsia, induced labor, cesarean delivery,
and emergency delivery)
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| General anesthesia: editorial by Hawkins and colleagues questioned whether GA being performed enough in
obstetrics to maintain skills; in 1997, 84% in United States received RA for cesarean delivery; in 1999, Germany
reported 27% received RA (currently much higher); remainder received GA; specific problems and
risks related to GA
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| Eating in labor: shortens duration of labor, helps achieve normal delivery, and improves experience for anesthesia
provider (unless intubating during nausea and vomiting); confidential inquiries into maternal deaths
show dramatic decline in deaths from aspiration from 1952 to 1999; continue controlling what patients eat in
labor; ACOG suggests patients in active labor should avoid ingestion of anything, except sips of clear liquid,
occasional ice chips, or preparation to moisten mouth and lips; when significant hydration necessary, it
should be given by intravenous (IV) infusion
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| Hemorrhage: postpartum hemorrhage most common (not placenta previa); important to recognize and respond
to massive hemorrhage in delivery room or recovery area
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| Use of oxytocin (Pitocin): should not be given as rapid bolus; results in decreased BP and increased heart rate
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| Uterine rupture and vaginal birth after cesarean section (VBAC): area of concern and risk; uterine rupture
rate ≤1%; current issues and guidelines may help decrease problem
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| Cesarean delivery rate: increasing in United States (≈29%) and around world; World Health Organization
suggests worldwide rate 15%; increased mortality with cesarean delivery (less with elective cesarean delivery)
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| Conclusion: important to know patient, communicate with obstetric colleagues before involvement with significant
patient (eg, cardiac disease, major medical problems), plan ahead (understand areas of risk), and equip
labor-and-delivery suite
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Educational Objectives
| The goal of this program is to educate the listener about the pregnant patient undergoing nonobstetric surgery
and avoiding maternal mortality. After hearing and assimilating this program, the participant will be better able
to:
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 | 1. Determine which women undergoing nonobstetric surgery need pregnancy testing.
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| 2. Debate the safety of midazolam and nitrous oxide during pregnancy and nonobstetric surgery.
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| 3. Review when and how fetal monitoring should be used in the pregnant patient undergoing nonobstetric
surgery.
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| 4. Examine whether the pregnant patient >24 wk gestation should have surgery in a specialty hospital without
a labor-and-delivery suite.
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| 5. Summarize the major causes of pregnancy-related maternal mortality in the United States.
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Discussed on This Program
Acetaminophen (N-acetyl-P-aminophenol; APAP) [several trade names]
Beractant (natural lung surfactant) [Survanta]
Bupivacaine HCl (several trade names)
Chlordiazepoxide [Libritabs, Librium, Mitran, Reposans-10]
Chloroprocaine HCl [Nesacaine, Nesacaine-MPF]
Diazepam [Diastat, Diazepam Intensol, Valium]
Halothane [Fluothane]
Isoflurane [Forane]
Ketamine HCl [Ketalar]
Lidocaine HCl (several trade names)
Midazolam HCl [Versed]
Nitrous oxide (N2 O)
Oxytocin [Pitocin]
Propofol [Diprivan]
Succinylcholine chloride [Anectine, Anectine Flo-Pack, Quelicin]
Thalidomide [Synovir, Thalomid]
Thiopental sodium [Pentothal]
Suggested Reading
Anand KJ et al: Anesthetic agents and the immature brain: are these toxic or therapeutic? Anesthesiology
101:527, 2004; Anderson FW et al: Sudden death: ectopic pregnancy mortality. Obstet Gynecol 103:1218,
2004; Balki M et al: Craniotomy for suprasellar meningioma in a 28-week pregnant woman without fetal heart
rate monitoring. Can J Anaesth 51:573, 2004; Bartlett LA et al: Risk factors for legal induced abortion-related
mortality in the United States. Obstet Gynecol 103:729, 2004; Bennett TA et al: Pregnancy-associated hospitalizations
in the United States in 1991 and 1992: a comprehensive view of maternal morbidity. Am J Obstet Gynecol
178:346, 1998; Berg CJ et al: Pregnancy-related mortality in the United States, 1991-1997. Obstet
Gynecol 101:289, 2003; Bouchard S et al: The EXIT procedure: experience and outcome in 31 cases. J Pediatr
Surg 37:418, 2002; Bucklin BA: Vaginal birth after cesarean delivery. Anesthesiology 99:1444, 2003; Cheng
YW et al: How long is too long: Does a prolonged second stage of labor in nulliparous women affect maternal
and neonatal outcomes? Am J Obstet Gynecol 191:933, 2004; Deneux-Tharaux C et al: Underreporting of
pregnancy-related mortality in the United States and Europe. Obstet Gynecol 106:684, 2005; Gissler M et al:
Pregnancy-associated mortality after birth, spontaneous abortion, or induced abortion in Finland, 1987-2000.
Am J Obstet Gynecol 190:422, 2004; Hawkins JL et al: Anesthesia-related deaths during obstetric delivery in
the United States, 1979-1990. Anesthesiology 86:277, 1997; Hawkins JL et al: General anesthesia for cesarean
section: are we really prepared? Int J Obstet Anesth 7:145, 1998; Hawkins JL et al: Maternal mortality in the
United States: where are we going and how will we get there? Anesth Analg 93:1, 2001; Hawkins JL: Anesthesia-related
maternal mortality. Clin Obstet Gynecol 46:679, 2003; Immer-Bansi A et al: Unnecessary emergency
caesarean section due to silent CTG during anaesthesia? Br J Anaesth 87:791, 2001; Landon MB et al:
Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. N Engl J Med
351:2581, 2004; Mazze RI et al: Halothane prevents nitrous oxide teratogenicity in Sprague-Dawley rats; folinic
acid does not. Teratology 38:121, 1988; Ong BY et al: Severe fetal bradycardia in a pregnant surgical patient
despite normal oxygenation and blood pressure. Can J Anaesth 50:922, 2003; Rosenberg L et al: Lack of
relation of oral clefts to diazepam use during pregnancy. N Engl J Med 309:1282, 1983; Wildman K et al: Maternal
mortality as an indicator of obstetric care in Europe. BJOG 111:164, 2004.
Faculty Disclosure
In adherence to ACCME guidelines, the Audio-Digest Foundation requests all lecturers to disclose any significant
financial relationship with the manufacturer or provider of any commercial product or service discussed.
For this issue, the faculty reported nothing to disclose.
Dr. Hawkins was recorded at the 59th Postgraduate Assembly in Anesthesiology presented December 9-13, 2005,
by the New York State Society of Anesthesiologists, Inc. and held in New York, NY; Dr. Hughes, at the Annual
Meeting and Anesthesiology Review Course jointly presented May 18-21, 2006, by the California Society of Anesthesiologists
and University of California, San Diego, School of Medicine and held in Rancho Mirage, CA.
The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of
this program.
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