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Anesthesia for Non-Obstetric Surgery in Pregnancy


Anesthesia for Non-Obstetric Surgery in Pregnancy Joe Dietrick, CRNA, M.A. Have A Nice Day Anesthesia, LLC Chillicothe, MO * * * * Intrauterine PG thought to be ... – PowerPoint PPT presentation

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Title: Anesthesia for Non-Obstetric Surgery in Pregnancy

Anesthesia for Non-Obstetric Surgery in Pregnancy
  • Joe Dietrick, CRNA, M.A.
  • Have A Nice Day Anesthesia, LLC
  • Chillicothe, MO

  • Identify the most common procedures
  • Identify factors of maternal safety, fetal
    teratogenicity, intrauterine asphyxia, preterm
  • Intraoperative FHR monitoring
  • Laparoscopic surgery
  • Anesthetic management

Introduction (1 of 3)
  • Surgeons approach to surgery in pregnancy
  • 1990 If medical or surgical treatment plan
    usually followed for a nonpregnant woman is
    altered because of pregnancy, there must be
    strong justification for its modification.
  • Occurrence Approx 50K/yr (1-2)

Introduction (2 of 3)
  • Most common procedures5
  • Appendectomy
  • Cholecystectomy
  • Ovarian disorders
  • Trauma
  • Breast / cervical dz
  • Bowel obstruction

Introduction (3 of 3)
  • 4 Areas of Unique Concern
  • Maternal safety
  • Fetal teratogenicity
  • Intrauterine fetal asphyxia
  • Preterm labor
  • Appropriate anesthetic care will require
    understanding of the current knowledge of these

Maternal Safety Significant changes after 1st
  • Uterine enlargement
  • AO/VC compression LUD gt 20 wks
  • Respiratory
  • Increased VO2 decreased reserve risks HYPOxia
  • Chronic resp alkalosis (PaCO2 32)
  • Potential AW difficulty
  • CNS
  • Up to 40 decrease in MAC
  • Increased LA sensitivity
  • GI
  • Increased aspiration risk from physical and
    biochemical changes gt 18-20 wks

Teratogenicity general
  • Fetal risk
  • 0-15d ? usually embryotoxic (EGA 2-4 wks)
  • 15-60d (organogenesis) ? great risk to fetus.
  • 31-71d EGA (4-10 wks)
  • Then functional deficits
  • Nearly all drugs have been demonstrated to be
    teratogenic in some species at some dose.

Teratogenicity Research Issues
  • Difficulty in applying animal human studies to
  • Variations in susceptibility between species
  • Human studies are retrospective
  • Difficulty in controls
  • Confounding multiple variables
  • Small numbers inadequate for statistical

Teratogenicity BZD, Opioids
  • BZD/minor tranquilizers
  • Associated with increased anomalies
  • BZD
  • Initally associated with increased cleft palates
  • Later studies no relationship
  • FDA (1975) minor tranquilizers should almost
    always be avoided in 1st trimester
  • Single dose no effect
  • Synthetic opioids animal studies not teratogenic

Teratogenicity MR, LA
  • Muscle relaxants
  • minimal placental transfer
  • Local Anesthetics
  • Lidocaine used in PG rats w/o complication
  • No evidence of problems in humans
  • Cocaine is a known teratogen
  • IUGR, preterm delivery, and increased risk of
    abruptio placentae

Teratogenicity Induction Agents
  • Induction Agents
  • Ketamine not teratogenic
  • gt1 mg/kg ? ?risk of preterm labor
  • Thiopental not teratogenic in conventional
  • Propofol in pregnant ewe1
  • No adverse fetal effects compared to thiopental
  • Propofol Succinylcholine ?demonstrated cases of
    severe maternal bradycardia in ewe

Teratogenicity N2O
  • N2O
  • Theoretical risk is decreased but reversible DNA
  • Pretreatment with folinic acid is not proven
    effective in preventing neurogenic teratogenicity
    in animals
  • Conclusion
  • Teratogenic only under extreme conditions
    however, slightly increased abortion risk?

Teratogenicity Inhalation Agents
  • Volatile anesthetics
  • Shown teratogenic in some species
  • VA N2O in PG rats showed no anomalies at any
    gestational age
  • Like N2O, slightly increased risk of abortion?

Teratogenicity non-drug factors
  • Anesthesia /or surgery may cause
  • HYPOxia
  • HYPOtension
  • HYPERcapnia
  • ? temp
  • ? / ? BS
  • Effects may be teratogenic

With a critical event, pose greatest fetal risk
Intrauterine Fetal Asphyxia (1 of 4)
  • Avoided by maintaining the following variables of
    fetal respiration
  • Maternal oxygenation
  • Maternal carbon dioxide tension
  • Uterine blood flow

Intrauterine Fetal Asphyxia (2 of 4)
  • Maternal oxygenation
  • HYPOxia can occur with either regional or general
  • HYPERoxia does not promote either fetal HYPOxia
    from UA constriction, or retrolental fibroplasia
  • Fetal pO2 lt60 due to maternal/placental
    mismatch and high placental VO2

Intrauterine Fetal Asphyxia (3 of 4)
  • Maternal CO2
  • Fetal CO2 related to maternal level
  • HYPOcapnia
  • Increased ventilation may reduce venous return or
    provoke UA vasoconstriction, and cause a fall in
  • Alkalosis reduces release of O2 from maternal
  • Target EtCO2 32-34 mmHg

Intrauterine Fetal Asphyxia (4 of 4)
  • Uterine blood flow
  • HYPOtension may be caused by
  • anesthetics (GA or RA)
  • AO/VC compression
  • Vasoconstriction may be caused by endogenous or
    exogenous sympathetic activity, including
    injection of ketamine (gt 2mg/kg)
  • Neostigmine (anti-Ach-ase)
  • Glyco, then slow admin with FHR monitoring

Preterm Labor (1 of 2)
  • Anesthetic effect on preterm labor unknown
  • Surgical procedures in abdomen and especially
    near uterus are associated with preterm labor
  • gt24 wks 22 delivered 1st week post-op
    appendectomy (1991, N778)

Preterm Labor (2 of 2)
  • Pre-emptive pro-gestational drugs
  • Have not been demonstrated effective at
    preventing preterm labor or abortion
  • Ketamine, vasopressors, anticholinesterases
  • increase uterine tone and therefore increase
  • Volatile agents
  • decrease uterine tone may have benefit

Intraoperative FHR monitoring
  • Horrigan, et al (1999)2 reviewed 12 articles
  • Conclusion 20 years experience ? no documented
    evidence that FHR monitoring intraoperatively is
  • Letter in response, by Kendrick Neiger
  • 18 cases, 10 non-cardiac
  • Uterine activity requiring tocolysis 3/10
  • One episode of bradycardia assoc. with EBL
  • Must individualize decision

ACOG Opinion 474 (02/2011)3
  • The decision to use fetal monitoring should be
    individualized and, if used, should be based on
    gestational age, type of surgery, and facilities
  • Ultimately, each case warrants a team approach
    (anesthesia and obstetric care providers,
    surgeons, pediatricians, and nurses) for optimal
    safety of the woman and the fetus.

More detail3
  • If FHR used
  • Neonatal/ped serv
  • CS capability available
  • Qualified individual for FHR interpretation
  • When
  • Previable FHR before after
  • Viable FHR Toco before after (minimum)

Intraoperative FHR?3
  • The fetus is viable.
  • It is physically possible to perform
    intraoperative electronic fetal monitoring.
  • A health care provider with obstetric surgery
    privileges is available and willing to intervene
    during the surgical procedure for fetal
  • When possible, the woman has given informed
    consent to emergency cesarean delivery.
  • The nature of the planned surgery will allow the
    safe interruption or alteration of the procedure
    to provide access to perform emergency delivery.

Laparoscopic Surgery4
  • No difference in indications
  • Timing
  • Elective avoid
  • Optimal Early 2nd trimester
  • Performed as late as 34 wks EGA
  • Initial trocar approach
  • No difference between open blind
  • Midline 6 cm above fundus

Laparoscopic Surgery4
  • Adverse effects of CO2 insufflation
  • Maternal ? fetal acidosis
  • Pneumoperitoneum 8 12 mmHg (lt 15)
  • Avoid N2O (or lt 50), extreme position
  • EtCO2 32 -34 mmHg
  • Hyperventilation deleterious

MAC Issues5
  • Risk of hypoventilation ? fetal acidosis
  • Difficulty in evaluating resp status
  • Potential difficulty with emergent AW
  • ? risk of aspiration
  • Compounded by co-existing morbidities

  • Timing
  • Avoid if possible
  • Risk vs benefit OB consult
  • Non-emergent early/mid 2nd trimester
  • Perioperative monitoring
  • Cont FHR uterine activity if possible.
  • FHR gt18 wks6 or gt 23 wks
  • Ability to perform emergent CS
  • Plan action for persistent fetal ? HR

  • Anesthesia
  • Both GA RA used
  • Maintaning variables of fetal well-being most
  • Regional generally preferred
  • gt 16 wks
  • Aspiration prophylaxis
  • Resolve dehydration / hypovolemia
  • LUD
  • Maintain variables of fetal well-being

  • Pneumatic compression devices perioperatively
  • Postoperative management
  • Opiates antiemetics as needed
  • Avoid NSAIDs, esp gt32 weeks
  • Emergent delivery
  • Effects of anesthetics may require neonatal
  • Muscle relaxants do NOT cross placenta

FDA Pregnancy Categories
  • Unless otherwise noted all information is from
    the OB text
  • Naughton, N Cohen, S. (2004). Non-obstetric
    Surgery in Pregnancy. In Chestnut, D. (Ed),
    Obstetric Anesthesia, Principles Practice, 3rd
    Ed ( Pg 255-272)
  • Other references
  • Alon, et al. Effects of propofol and thiopental
    on maternal and fetal cardiovascular and
    acid-base variables in the pregnant ewe.
    Anesthesiology. 1993 Mar78(3)562-76
  • Horrigan TJ, Villarreal R, Weinstein L. Are
    obstetrical personnel required for intraoperative
    fetal monitoring during nonobstetric surgery? J
    Perinatol. 1999 Mar19(2)124-6.
  • ACOG Committee Opinion Number 284 Non-obstetric
    surgery in pregnancy. Obstet Gynecol.
  • Stany, M, et al. Laparoscopic surgery in
    pregnancy. Retrieved 04/01/2011) from UpToDate.
    Website http//
  • Norwitz, E., Joong, S. Management of pregnant
    women undergoing non-obstetric surgery.
    Retrieved 04/01/2011) from UpToDate. Website
  • Ni Mhuircheartaigh RN, OGorman DA. Anesthesia in
    the pregnant patient for non-obstetric surgery. J
    Clin Anesth 20061860- 6.