This document discusses the anesthetic management of non-obstetric surgery in pregnant patients. It covers objectives of maternal safety and fetal consideration. It provides data on the timing of surgeries during pregnancy and their indications. It also discusses the altered maternal physiology during pregnancy and the implications for anesthesia management, including changes to the respiratory, cardiovascular and coagulation systems. Potential risks to the fetus from surgery and anesthesia are outlined. Finally, it reviews various anesthetic agents and the current evidence regarding their teratogenicity in humans.

1. ANAESTHETIC MANAGEMENT
OF NON OBSTETRIC SX IN
OBSTETRIC PTS
PRESENTER:DR.RICHARDSON RESIDENT
MODERATOR:DR.SRIKANTH (ASST PROFESSOR)
DR.KEERTHI (ASST PROFESSOR)

2. OBJECTIVES
 MATERNAL SAFETY
 FETAL CONSIDERATION
 PRACTICAL CONSIDERATIONS

3.  SURGERY MAY BE NECESSARY DURING ANY STAGE OF PREGANCY
 AMONG SWEDISH WOMEN WHO HAD SURGERY DURING PREGNANCY
 42% OCCURRED IN FIRST TRIMESTER
 35%OCCURED DURING SECOND TRIMESTER
 23% OCCURRED DURING THRID TRIMESTER
 LAPROSCOPY FOR GYNAECOLOGICAL PROCEDURES WAS MOST
COMMON DURING 1ST TRIMESTER
 APPENDECTOMY WAS MOST COMMON DURING REST OF PREGANANCY

4. INDICATIONS FOR PREGNANCY
RELATED SX
 CERVICAL CERCLAGE
 OVARIAN CYST
 CONDITIONS AMNEABLE TO FETAL SX

5. INDICATIONS FOR NON PREGNANCY
RELATED SX
 ACUTE ABDOMINAL DISEASES (MOST COMMONLY APPENDICITIS AND
CHOLECYSTITIS)
 MALIGNANCIES AND TRAUMA

6. POSSIBLE RISKS TO FETUS FOR
ANTENATAL SX
 THE EFFECTS OF DISEASE PROCESS ITSELF OR RELATED THERAPIES
 TERATOGENECITY OF ANESTHETIC AGENTS OR OTHER DRUGS GIVEN IN
PERIOOERTIVE PERIOD
 INTRAOPERATIVE PERTUBATIONS OF UTEROPLACENTAL PERFUSIONS
AND/OR FETAL OXYGENATION
 RISK FOR ABORTIONS OR PRETERM DELIVERY

7. ALTERED MATERNAL PHYSIOLOGY
 PROFOUND CHANGES IN MATERNAL PHYSIOLOGY RESULTS FROM
 INCREASED CONCENTRATIONS OF VARIOUS HARMONES
 MECHAMICAL EFFECTS OF GRAVID UTERUS
 GREATER METABOLIC DEMAND
 HEMODYNAMIC CONSEQUENCES OF LOW PRESSURE PLACENTAL
CIRCULATIONS
 MECHANICAL EFFECTS BECOME APPARENT WHEN THE UTERUS EMERGES
FROM PELVIS DURING SECOND HALF OF GESTATION

8. RESPIRATORY SYSTEM AND ACID BASE
BALANCE CHANGES
 ALVEOLAR VENTILATION INCREASES BY 30% OR MORE BY MID
PREGNANCY
 THIS RESULTS IN CHRONIC RESPIRATORY ALKALOSIS WITH PaCO2 OF 28-
32 mmHG ,SLIGHTLY ALKALINE pH AND DECREASED BICARBONATE AND
BUFFER BASE
 FRC DECREASES BY 20% AS THE UTERUS EXPANDS RESULTING IN
DECREASED O2 RESERVES AND POTENTIAL FOR AIRWAY CLOSURE
 WIEIGHT GAIN DURING PREGNANCY AND CAPILLARY ENGORGEMENT OF
THE RESPIRATORY TRACT MUCOSA LEADS TO MORE FREQUENT
PROBLEMS WITH MASK VENTILATION AND INTUBATIONS

9.  ALVEOLAR HYPERVENTILATION AND DECREASED FRC ALLOW FASTER
EQUILIBRATION OF INHALED ANAESTHETICS
 THERE IS 30-40% DECREASE IN MAC FOR VOLATILE ANAESTHETICS

10. CARDIOVASCULAR SYSTEM CHANGES
 CARDIAC OUTPUT INCREASES BY 50% DURING PREGNANCY BECAUSE OF
INCREASE IN HEART RATE AND STROKE VOLUME BUT MYOCARDIAL
CONTRACTILITY IS UNCHANGED
 THERE IS DECREASE IN BOTH SYSTEMIC AND PULMONARY VASCULAR
RESISTANCE
 DURING SECOND HALF OF THE GESTATION THE UTERUS COMPRESSES
THE IVC IN SUPINE POSITION AND REDUCES THE VENOUS RETURN AND
CARDIAC OUT BY 30%
 WHICH MIGHT LEAD TO CAUSE SUPINE HYPOTENSION SYNDROME WHEN
NEURAXIAL BLOCK OR GENERAL ANAESTHESIA ABOLISHES THE
COMPENSATORY MECHANISMS

11. CHANGES IN BLOOD VOLUME AND
BLOOD CONSTITUENTS
 BLOOD VOLUME STARTS EXPANDING IN FIRST TRIMESTER AND
INCREASES BY 30-45% BY TERM
 DILUTIONAL ANAEMIA OCCURS AS A RESULT OF SMALLER INCREASE IN
RED BLOOD CELL MASS COMPARED TO PLASMA VOLUME
 ALTHOUGH MODERATE BLOOD LOSS IS WELL TOLERATED DURING
PREGNANCY PRE EXISTING ANAEMIA DECRASES PTS RESERVES WHEN
SIGNIFICANT HEMORRHAGE OCCURS
 PREGNANCY IS A HYPERCOAGUABLE STATE INCREASES IN FIBRINOGEN
FACTORS 7,810,12 AND FIBRIN DEGRADATION PRODUCTS
 PREGNANCY REPRESENTS A STATE OF ACCELERATED BUT COMPENSATED
INTRAVASCULAR COAGULATION

12. FETAL CONSIDERATIONS
 RISK OF TERATOGENICITY:
 Teratogenicity has been defined as any significant postnatal change in function
or form in an offspring after prenatal treatment.
 Unfortunately, prospective clinical studies of the teratogenic effects of
anesthetic agents are impractical; such studies would require huge numbers of
patients exposed to the drug under investigation.
 Therefore, investigations of anesthetic agents have taken one of the following
directions:
 (1) studies of the reproductive effects of anesthetic agents in small animals,
 (2) epidemiologic surveys of operating room personnel constantly exposed to
subanesthetic concentrations of inhalation agents, and
 (3) studies of pregnancy outcome in women who have undergone surgery
while pregnant

13. Principles of Teratogenicity
 A number of important factors influence the teratogenic potential of a
substance, including species susceptibility, dose of the substance, duration
and timing of exposure, and genetic predisposition.
 The interaction between dose and timing is also critical.
 A small dose of a teratogen may cause malformations or death in the
susceptible early embryo, whereas much larger doses may prove harmless
to the fetus
 Manifestations of teratogenicity include death, structural abnormality,
growth restriction, and functional deficiency.2

14.  The stage of gestation at which exposure occurs determines the target
organs or tissues, the types of defects, and the severity of damage
 Most structural abnormalities result from exposure during the period of
organogenesis, which extends from approximately day 31 to day 71 after
the first day of the last menstrual period
 Functional deficiencies are usually associated with exposure during late
pregnancy or even after birth, because the central nervous system (CNS)
continues to mature during this period.

16.  Shepard has listed several criteria for determining that an agent is a
human teratogen, including the following:
 (1) proven exposure to the agent at the critical time of development
 (2) consistent findings in two or more high-quality epidemiologic studies;
 (3) careful delineation of the clinical cases, ideally with the identification of
a specific defect or syndrome;
 (4) an association that “makes biological sense.” Documentation of
teratogenicity in experimental animals is important but not essential.

17. 1. The list of agents or factors that are proven human teratogens does not
include anesthetic agents (which are listed as “unlikely teratogens”) or any
drug routinely used during the course of anesthesia

18. Nondrug Factors Encountered in the
Perioperative Period
 Derangements of Normal Physiology: Anesthesia and surgery can cause
derangements of maternal physiology that may result in hypoxia,
hypercapnia, stress, and abnormalities of temperature and carbohydrate
metabolism
 These states may be teratogenic themselves, or they may enhance the
teratogenicity of other agents.
 The chronic hypoxemia experienced by mothers at high altitudes results in
the delivery of infants with lower birth weights but with no increase in the
rate of congenital defects.

19.  Hypothermia is not teratogenic, whereas hyperthermia is teratogenic in
both animals and humans.
 Congenital anomalies, especially involving the CNS, have repeatedly been
associated with maternal fever during the first half of pregnancy.
 It must be remembered that fetal temperature is on average 0.5°C to 1°C
higher than maternal temperature.
 Embryonic oxidative stress from reactive oxygen species has been
implicated as one of the mechanisms involved in teratogenicity of many
agents

21. Effects of Systemic Agents
 Teratogenesis has not been associated with the use of any of the
commonly used induction agents
 including the barbiturates, ketamine, and the benzodiazepines—when they
were administered in clinical doses during anesthesia.
 Similarly, no evidence supports the teratogenicity of opioids in humans;
there is no increase in the incidence of congenital anomalies among
offspring of mothers who use morphine or methadone during pregnancy

22.  Although human data relating to long-term tranquilizer therapy have
raised questions about the possible teratogenicity of some agents,
 most studies are retrospective and suffer from a variety of methodologic
flaws.
 Benzodiazepine therapy became controversial after an association
between maternal diazepam ingestion during the first trimester and
infants with cleft palate, with or without cleft lip, was reported.
 Subsequently, prospective work in 854 women who ingested diazepam
during the first trimester did not demonstrate a higher risk associated with
benzodiazepine therapy

23. Local Anesthetics
 no evidence supports teratogenicity associated with any local anesthetic
used clinically in humans.
 Maternal cocaine abuse is associated with adverse reproductive outcomes,
including abnormal neonatal behaviour
 in some reports, a higher incidence of congenital defects of the
genitourinary and gastrointestinal tracts.
 The greatest risk to the fetus most likely results from the high incidence of
placental abruption associated with maternal cocaine use

24. Muscle Relaxants
 Fujinaga et al.56 used the whole-embryo rat culture system to investigate
the reproductive toxicity of high doses of d-tubocurarine, pancuronium,
atracurium, and vecuronium
 . Although dose-dependent toxicity was manifested, these effects occurred
only at concentrations 30-fold greater than those encountered in clinical
practice
 Given that fetal blood concentrations of muscle relaxants are only 10% to
20% of maternal concentrations, these drugs appear to have a wide margin
of safety when administered to the mother during organogenesis

25.  Prolonged disturbance of normal muscular activity by muscle relaxants has
caused axial and limb deformities in the chick but has seldom been seen in
other experimental animals
 . Although one case report described arthrogryposis (i.e., persistent joint
flexure) in the infant of a woman with tetanus who received d-tubocurarine
for 19 days beginning at 55 days’ gestation
 the patient also was hypoxic and received multiple other drugs.
 Many women have received muscle relaxants for several days during late
gestation without adverse effect on the neonate.

26. Inhalation Anesthetics
 Nitrous Oxide:In vivo and embryo culture studies in rats have confirmed
that nitrous oxide has several adverse reproductive effects, each of which
results from exposure at a specific period of susceptibility.
 Fetal resorptions occurred after exposure on days 8 and 11 of gestation,
skeletal anomalies after exposure on day 8 or 9, and visceral anomalies
(including situs inversus) only when exposure occurred on day 8
 Initially, teratogenicity associated with nitrous oxide was thought to result
from its oxidation of vitamin B12, which interferes with its function as a
coenzyme for methionine synthase.

27.  Transmethylation from methyltetrahydrofolate to homocysteine to produce
tetrahydrofolate (THF) and methionine is catalyzed by methionine synthase
 Thus, methionine synthase inhibition could cause a decrease in THF (with a
resultant decrease in DNA synthesis) and lower methionine levels

28.  Nitrous oxide rapidly inactivates methionine synthase in both animals and
humans.
 Prolonged human exposure to nitrous oxide leads to neurologic and
hematologic symptoms, the latter probably resulting from diminished DNA
synthesis

29. Human Studies.
 Occupational Exposure to Waste Anesthetic Agents: Epidemiologic surveys
dating from the 1960s and 1970s suggested that reproductive hazards (e.g.,
spontaneous abortion, congenital anomalies) were associated with operating
room and dental surgery work
 These hazards were attributed to exposure to trace concentrations of
anesthetic agents, principally nitrous oxide
 The most consistent risk associated with occupational exposure was
spontaneous abortion, which carried a relative risk ratio of 1.3. The ratio for
congenital anomalies (1.2) had borderline statistical significance
 A hazards model predicted a 2.5-fold increase in preterm delivery risk in
women exposed to unscavenged gas 1 or more hours per week compared with
an unexposed group

30.  It is possible that the higher waste levels of nitrous oxide encountered in
dentists’ offices pose a reproductive risk.
 Overall, the epidemiologic data do not support an increased risk for
congenital anomalies with long-term exposure to nitrous oxide

31. Studies of Operations Performed
during Pregnancy
 Various studies like 1. In 1963, Smith9 2. In 1965, Shnider and Webster97 3.
Brodsky et al.
 4. Duncan et al. observed that rate of sponataneous abortions and pre
term deliveries were high among the pt who underwent surgeries during
pregnancy
 In summary, although anesthesia and surgery are associated with a higher
incidence of abortion, fetal growth restriction, and perinatal mortality,
 these adverse outcomes can often be attributed to the procedure, the site
of surgery (e.g., proximity to the uterus), and/or the underlying maternal
condition

32.  Evidence does not suggest that anesthesia during pregnancy results in an
overall increase in congenital abnormalities
 and there is no evidence of a relationship between outcome and type of
anesthesia

33. Behavioral Teratology
 It is well known that some teratogens produce enduring behavioral
abnormalities without any observable morphologic changes
 The CNS may be especially sensitive to such influences during the period
of major myelination, which in humans extends from the fourth
intrauterine month to the second postnatal month
 Several studies have shown that brief intrauterine exposure to halothane
adversely affects postnatal learning behavior and causes CNS
degeneration and decreased brain weight in rats.1
 in humans, investigations of the effects of maternally administered
analgesics at delivery have revealed transient, dose-related depression of
neonatal behavior

34.  The implications, if any, for the human fetus during the maternal
administration of general anesthesia are unknown
 Surgery may result not only in exposure to anesthetic agents but also in
derangements in maternal physiology (e.g., hypoxia, stress, hypoglycemia)
that can lead to apoptosis during the critical period of neuronal
development

35. Fetal Effects of Anesthesia
 maintenance of Fetal Well-Being:The most serious fetal risk associated
with maternal surgery during pregnancy is that of intrauterine asphyxia
 Because fetal oxygenation depends on maternal oxygenation, maintenance
of normal maternal arterial oxygen tension, oxygen-carrying capacity,
oxygen affinity, and uteroplacental perfusion are critical to fetal well-being.

36. Maternal and Fetal Oxygenation
 Severe maternal hypoxemia results in fetal hypoxia and, if persistent, may
cause fetal death.
 Any complication that causes profound maternal hypoxemia (e.g., difficult
intubation, esophageal intubation, pulmonary aspiration, total spinal
anesthesia, systemic local anesthetic toxicity) is a potential threat to the
fetus
 McClain et al.117 observed that the maternal administration of general
anesthesia for 4 hours in gravid ewes produced an initial—but not
sustained—increase in fetal systemic oxygenation,

37.  , which was accompanied by a sustained increase in fetal cerebral
oxygenation.
 The investigators hypothesized that the increase in fetal cerebral
oxygenation resulted from greater cerebral perfusion, lower cerebral
metabolic rate, or both.
 Histologic examination found no evidence of neurotoxicity

38. Maternal Carbon Dioxide and Acid-
Base Status.
 Maternal hypercapnia can cause fetal acidosis, because fetal Paco2
correlates directly with maternal Paco2.
 Although mild fetal respiratory acidosis is of little consequence, severe
acidosis can cause fetal myocardial depression and hypotension.
 Respiratory or metabolic alkalosis can compromise maternal-fetal oxygen
transfer by causing umbilical artery constriction and by shifting the
maternal oxyhemoglobin dissociation curve to the left.1

39.  In addition, hyperventilation, independent of changes in Paco2, may
reduce uterine blood flow and cause fetal acidosis.
 This decrease most likely is a consequence of mechanical ventilation,
whereby increased intrathoracic pressure reduces venous return and
cardiac output, which in turn decreases uteroplacental perfusion.
 Thus, hyperventilation should be avoided in the pregnant surgical patient.
Rather, the Paco2 should be kept in the normal range for pregnancy

40.  Maternal hypotension from any cause can jeopardize uteroplacental
perfusion and cause fetal asphyxia.
 The most common causes of hypotension in the pregnant patient
undergoing surgery include
 (1) deep levels of general anesthesia,
 (2) sympathectomy with high levels of spinal or epidural blockade
 (3) aortocaval compression,
 (4) hemorrhage, and
 (5) hypovolemia

41. Fetal Effects of Inhalation Agents
 The volatile halogenated anesthetic agents can affect the fetus directly (by
depressing the fetal cardiovascular system or CNS) or indirectly (by
causing maternal hypoxia or hypotension).
 Uterine perfusion was maintained during the inhalation of 1.0 and 1.5 MAC
halothane or isoflurane, because uterine vasodilation compensated for
small decreases in maternal blood pressure,in fetal lambs
 The relevance of these data to the human mother undergoing surgery
during pregnancy is not clear. Clinical experience does not support
avoidance of volatile agents, provided that maternal hypotension is
prevented

42.  If intraoperative fetal heart rate (FHR) monitoring reveals signs of fetal
compromise, it may be advisable to discontinue the volatile agent until the
fetal condition improves.

43. Fetal Effects of Systemic Drugs
 Opioids and induction agents decrease FHR variability, possibly to a
greater extent than the inhalation agents.
 Fetal respiratory depression is relevant only if cesarean delivery is to be
performed at the same time as the surgical procedure.
 Even then, high-dose opioid anesthesia need not be avoided when it is
indicated for maternal reasons(anesthesia for patients with cardiac
disease).
 The pediatrician should be informed of maternal drug administration so
that preparations can be made to support neonatal respiration

44.  Maternal administration of muscle relaxants and reversal agents typically
has not proved to be problematic for the fetus.
 It has been suggested that rapid intravenous injection of an
anticholinesterase agent might stimulate acetylcholine release, which
might cause increased uterine tone and thus precipitate preterm labor.
 Although this concern is unproven, slow administration of an
anticholinesterase (after prior injection of an anticholinergic agent) is
recommended.
 Although neither atropine nor glycopyrrolate significantly affects FHR
when standard clinical doses are administered, glycopyrrolate is often
recommended because it crosses the placenta less readily and may be a
more effective antisialagogue.

45.  One case report described mild fetal bradycardia when neostigmine was
administered with glycopyrrolate during emergence from general
anesthesia at 31 weeks’ gestation.
 This problem did not occur during the administration of a second general
anesthetic to the same patient 4 days later, when atropine was
administered with neostigmine, presumably because atropine undergoes
greater placental transfer than glycopyrrolate.
 Because the effects of reversal agents are unpredictable, the monitoring of
FHR during maternal drug administration is suggested

46.  Sodium nitroprusside and esmolol have been used during pregnancy to
induce hypotension during surgical procedures.
 Standard doses of nitroprusside have proved to be safe for the fetus146;
the risk for fetal cyanide toxicity appears to be low, provided that
tachyphylaxis does not occur and the total dose is limited.
 The use of esmolol during pregnancy remains controversial. Ostman et al.
observed minimal fetal effects after the administration of esmolol in gravid
ewes
 whereas Eisenach and Castro1 reported significant decreases in FHR and
blood pressure as well as a modest reduction in fetal Pao2

47. Prevention of Preterm Labor
 Most epidemiologic studies of nonobstetric surgery during pregnancy
have reported a higher incidence of abortion and preterm delivery
 It is unclear whether the surgery, manipulation of the uterus, or the
underlying condition is responsible.
 Second-trimester procedures and operations that do not involve uterine
manipulation carry the lowest risk for preterm labor.

48.  Although the volatile agents depress myometrial irritability and thus are
theoretically advantageous for abdominal procedures,
 evidence does not show that any one anesthetic agent or technique
positively or negatively influences the risk for preterm labor.
 Published evidence does not support the routine use of prophylactic
tocolytic agents.
 Monitoring for uterine contractions may be performed intraoperatively
with an external tocodynamometer (when technically feasible) and for
several days postoperatively, allowing tocolytic therapy to be instituted, if
appropriate.

49.  Additional surveillance is necessary in patients who receive potent
postoperative analgesics, who may be unaware of mild uterine contractions.
 Magnesium sulfate is among the most common drugs used in pregnancy as a
tocolytic, anticonvulsant, or fetal neuroprotective agent.
 Antenatal magnesium sulfate has been shown to reduce the incidence and
severity of cerebral palsy after very preterm birth
 However, magnesium has concurrent effects that are relevant to the delivery
of anesthesia, including an increase in the rate of onset of neuromuscular
blockade
 the reestablishment of neuromuscular blockade in patients recovering from a
nondepolarizing muscle relaxant,158 a reduction in general anesthetic
requirements,159 and possible impairment in coagulation (as a calcium
antagonist)

50. PRACTICAL CONSIDERATIONS
 Timing of Surgery: Elective surgery should not be performed during
pregnancy. When possible, surgery should be avoided during the first
trimester, especially during the period of organogenesis.
 The second trimester is the optimal time to perform surgery, because the
risk for preterm labor is lowest at that time.
 In the event of a serious maternal illness, the remote fetal risks associated
with anesthesia and surgery are of secondary importance
 The primary goal is to preserve the life of the mother

51. Abdominal Emergencies

52. Laparoscopy
 Concerns exist about the effects of laparoscopy on fetal well-being,
especially the risks for
 (1) uterine or fetal trauma,
 (2) fetal acidosis from absorbed carbon dioxide,
 (3) decreased maternal cardiac output and uteroplacental perfusion
resulting from an iatrogenic increase in intra-abdominal pressure.
 In a study in gravid ewes, a marked increase in Paco2 to end-tidal CO2
gradient developed during CO2 insufflation,
 suggesting that Paco2 should be used to guide ventilation if maternal and
fetal acidosis are to be avoided.1

53.  . Potential benefits include
 (1) shorter hospitalization,
 (2) less postoperative pain,
 (3) decreased risk for thromboembolic and wound complications, and
 (4) faster return to normal activities, including earlier return of normal
gastrointestinal function, less uterine irritability, and less fetal depression

55. Direct-Current Cardioversion
 Direct-current (DC) cardioversion may be necessary during pregnancy
 . It is safe in all stages of pregnancy. The electrical current that reaches the
fetus is small
 Careful FHR monitoring during the procedure is required, as is left uterine
displacement to avoid aortocaval compression
 The risk for pulmonary aspiration of gastric contents associated with
sedation (with an unprotected airway) should be weighed against the risk
for general anesthesia with tracheal intubation

56.  Regardless of whether sedation or general anesthesia is selected
 a nonparticulate oral antacid should be administered;
 administration of a histamine-2 receptor antagonist to increase gastric pH
should also be considered

57. Maternal Cardiac Arrest and
Resuscitation
 Initiation of treatment for maternal cardiac arrest differs little from that in
the nonpregnant patient.
 Left uterine displacement should be maintained during resuscitation,
 and hand position should be 1 to 2 cm higher on the sternum because of
the upward shift of the diaphragm

58.  Perimortem cesarean delivery is an essential aspect of maternal
resuscitation for women in the second half of gestation.
 The primary purpose of the hysterotomy is to improve the chance of
maternal survival, but early delivery will also improve the likelihood of fetal
survival.
 Thus, if initial resuscitative efforts are unsuccessful, perimortem cesarean
delivery should be initiated within 4 minutes of the arrest with the goal of
delivering the fetus within 5 minutes

59.  The reversible causes of cardiac arrest during pregnancy are similar to
those in nonpregnant patients.
 Additional causes specific to pregnancy include 1.amniotic fluid
embolism, 2.eclampsia, 3.placental abruption, and hemorrhage.

60. Fetal Monitoring during Surgery
 Continuous FHR monitoring (using transabdominal Doppler
ultrasonography) is feasible beginning at 18 to 20 weeks’ gestation.
 Transabdominal monitoring may not be possible during abdominal
procedures or when the mother is very obese;
 thus, the intraoperative use of use of transvaginal Doppler
ultrasonography may be considered in selected cases.

61.  FHR variability, which typically is a good indicator of fetal well-being, is
present by 25 to 27 weeks’ gestation.
 Changes in the baseline FHR and FHR variability caused by anesthetic
agents or other drugs must be distinguished from changes that result from
fetal hypoxia
 . Persistent severe fetal bradycardia typically indicates true fetal
compromise.
 An unexplained change in FHR mandates the evaluation of maternal
position, blood pressure, oxygenation, and acid-base status and the
inspection of the surgical site
 to ensure that neither surgeons nor retractors are impairing uteroplacental
perfusion

63. Anesthetic Management
 Preoperative Management: Pregnant women are at increased risk for
acid aspiration after 18 to 20 weeks’ gestation (see earlier discussion).
 Pharmacologic precautions against acid aspiration may include
preanesthetic administration of
 a histamine receptor antagonist,
 i.v metoclopramide 0.15 mg /kg (increases LES tone and has antiemetic
effect)
 and a clear nonparticulate antacid such as sodium citrate solution 30 ml
30 mins before sx is advised

64. Choice of Anesthesia
 Maternal indications and consideration of the site and nature of the
surgery should guide the choice of anesthesia
 When possible, however, local or regional anesthesia is preferred, because
it permits the administration of drugs with no laboratory or clinical
evidence of teratogenesis
 In addition, maternal respiratory complications occur less frequently with
local and regional anesthetic techniques. These techniques are suitable for
cervical cerclage and urologic or extremity procedures.

65. Monitoring
 Maternal monitoring should include
 noninvasive or invasive blood pressure measurement,
 electrocardiography,
 pulse oximetry,
 capnography,
 temperature monitoring,
 The FHR and uterine activity should be monitored both before and after
surgery.

66. Anesthetic Technique
 General anesthesia mandates tracheal intubation beginning at 18 to 20
weeks’ gestation or if the stomach is full.
 Denitrogenation (i.e., preoxygenation) should precede the induction of
anesthesia
 Drugs with a history of safe use during pregnancy include thiopental,
propofol, morphine, fentanyl, succinylcholine, and the nondepolarizing
muscle relaxants
 Scientific evidence does not support avoidance of nitrous oxide during
pregnancy, particularly after the sixth week of gestation.

67.  A cautious approach would restrict nitrous oxide administration to a
concentration of 50% or less and would limit its use in extremely long
operations.
 Hyperventilation should be avoided; rather, end-tidal CO2 should be
maintained in the normal range for pregnancy
 Rapid intravenous infusion of 500 mL of crystalloid immediately before or
during the initiation of spinal or epidural anesthesia seems prudent,
 although the anesthesia provider should not assume that this measure
will prevent maternal hypotension.

68.  Vasopressors should be available to treat hypotension if it occurs.
Maternal hypotension should be treated aggressively
 .The usual precautions must be taken to guard against a high neuraxial
blockade and systemic local anesthetic toxicity
 Regardless of the anesthetic technique, steps to avoid hypoxemia,
hypotension, acidosis, and hyperventilation are the most critical elements
of anesthetic management.

69. Postoperative Management
 The FHR and uterine activity should be monitored during recovery from
anesthesia
 Adequate analgesia should be ensured with systemic or neuraxial opioids,
acetaminophen, or neural blockade
 Nonsteroidal inflammatory agents may be used until the second half of
pregnancy, at which time they should be used with caution.
 Prophylaxis against venous thrombosis should be considered, especially if
patients are immobilized

70. REFERENCES
 CHESTNUTS TEXTBOOK OF OBSTETRIC ANAESTHESIA

71. THANK YOU