Anesthesia for the Pregnant patient Undergoing Nonobstetric surgery

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Anesthesia for the Pregnant patient Undergoing
Nonobstetric surgery

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• R4 ? ??

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• Routine surgical Pt. happen to be pregnant
• ? anxiety
  for most of us.
• 2 of parturients surgery during
  pregnancy(80,000/yr)
• - traumatic injury, ovarian cysts,
  appendicitis, cholelithiasis, breast biopsy,
  cervical incompetence
• Despite of favorable results strong aversion to
  drugs and procedures performed during pregnancy
• ? when pregnant women exposed to
  non-teratogenic drugs estimate 25 risk of
  congenital malformation
• How do we counsel a pregnant patient?
• What can you tell her about the risks to her
  pregnancy associated with anesthesia?

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Physiology and Risk Assessment

• Alteration in maternal physiology
• - Respiratory oxygen consumption?, FRC ?, pCO2
  ?,
• mucosal vascularity with
  potential bleeding?,
• difficult intubation.
• - Cardiovascular blood volume, C.O. ?,
  dilutional anemia,
• aortocaval compression
  when supine,
• vascular responsiveness ?.
• - Gastrointestinal unclear-gastric volume, pH,
  emptying
• G-E sphincter tone ?.
• - CNS MAC ?, local anesthetic requirements ?.

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• Maintenance of uterine perfusion
• - utmost importance to anesthetic during
  pregnancy
• - maternal oxygenation and fetal oxygenation
• - Avoid maternal hypoxia and hypotension
• Prevention and treatment of preterm labor
• - most difficult problem to overcome
• - m/c cause of fetal loss
• - not related anesthetic therapies,
• but to the underlying disease and the
  surgery itself.
• - no reliable therapies
• - most studies pregnant women who require
  surgery
• deliver earlier, and smaller babies

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Teratogenic effects of anesthetics

• Never demonstrated in human but probably minimal
• nitrous oxide
• - in animal adrenergin tone ? ? uterine
  vasoconstriction
• ? abortion, congenital
  anomaly
• - in human not demonstrated despite extensive
  use
• Benzodiazepine
• - oral cleft anomaly reported
• - but case-control, prospective study no
  relationship
• Opiods, iv induction agents, local anesthetics
• long history of safety

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• NMDA blocker, GABAA enhancer
• neurodegeneration, memory impairment in
  animal
• but in human unclear
• ? and these results associated with other
  anesthetic
• conditions(hypoxia, respiratory acidosis,
  starvation)?
• ? change our clinical practice?

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ANESTHETIC MANAGEMANT

• Preoperative assessment
• - pregnancy test pregnancy status unsure
• patient request
• 3 weeks elapsed LMP
• - 12-50 age LMP record in anesthetic chart.
• - if possible, delay to second trimester,
  postpartum
• - aspiration prophylaxis antacid, MXL,
  H2-antagonist
• - preoperative tocolytics
• indomethacin - few anesthetic implication
• magnesium sulfate potentiate NDMR,
  hypotension

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• Intraoperative management
• - Type of surgery, anesthetic, trimester, length
  of anesthesia no study has shown pregnancy
  outcome
• - pCO2 about 10 torr ? due to ? minute
  ventilation
• - avoid hypogylcemia ? BST
• - fetal monitoring team approach
• (surgeon, obsterician,
  anesthesiologist)
• loss of beat-to-beat variability normal
• but fetal bradycardia not
• deceleration increase maternal
  oxygenation, BP,
• uterine displacement,
  change
• surgical retraction,
  tocolysis.
• urgent situation, abdominal op - impractical

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• General anesthesia
• - full preoxygenation, rapid sequence induction,
  avoid
• hypoxia, slow reversal of relaxants
• - keep in mind airway is more edematous,
  vascular,
• and difficult
  visualization
• - propofol ? oxytocin-induced contraction(animal)
  
• - in 1st trimester, high dose ketamine(gt2mg/kg)
• may cause uterine hypertonus
• - inhalation agent
• keep lt 2.0 MAC (prevent maternal C.O. ?)

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• Regional techniques
• - minimizing drug exposure, change in FHR
• - prevent hypotension with volume replacement,
• uterine tilt, treat hypotension agressively
• - local anesthetic dose 1/3 of nonpregnant
  patient
• - exellent opstoperative pain control
• ? can report Sx. of preterm labor
• maintain FHR variability
• early mobilization

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• Postoperative period
• - monitoring FHR and uterine activity
• - preterm labor treat early and aggressively
• - parenteral pain medication
• ? FHR variability ? regional tech. if
  possible
• - high risk for thromboembolism ? early
  mobilization
• if not possible, prophylactic
  anticoagulation

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SPECIAL SITUATIONS

• Cervcial cerclage
• recent study may not be beneficial
• m/c surgical procedure during pregnancy
• Trauma
• fetal loss due to maternal death, placental
  abruption
• early ultrasound in ER to determine fetal
  viability,
• fetal monitoring should be continued
• emergent c/sec indication
• - stable mather with a viable fetus in
  distress
• - traumatic uterine rupture
• - uterus interfereing with intra-abdominal
  repair
• - mother who cant be save with a viable
  fetus

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• Neurosurgical procedures
• aneurysmal clipping, AVM repair
• fetal monitoring
• - hypotension, large volume shift, blood loss
• aggressive diuresis - reduce uterine
  perfusion,
• fetal
  dehydration
• hyperventilation
• - reduce maternal C.O.
• - O2-Hb dissociation curve
• shift to left ? oxygen release to fetus ?

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• Cardiac surgery requiring bypass
• physiologic increase in blood volume and C.O.
• - maximal at 28-30 wks. ? cardiac
  decompensation
• another high-risk period
• - immediate postpartum (aortocaval compression
  ?,
• uteroplacental autotransfusion ?
  C.O. ?)
• op Ix. severe cardiac Sx.
• - unresponsive to medical management
• if possible, surgery delay to 2nd trimester
• over 24wks fetal monitor, left uterine
  displacement
• higher bypass flow and pressure
• benefit uterine blood flow, and fetal
  oxygenation

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• Laparoscopic techniques
• fetal outcome - similar in laparotomy and
  laparoscopy
• in near-term sheep
• - CO2 pneumoperitoneum not cause hypoxia,
  fetal hemodynamic change ? but induce respiratory
  acidosis
• intra-abdominal pr ? maintain as low as
  possible
• operative time kept to minimum
• fetal shielding during cholangiogram, left
  lateral table rotation, pneumatic stoking.

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Conclusions

• Anesthesiologists should reassure the mother that
  anesthetic drug and techniques will not her fetus
  or pregnancy at risk
• Prevention of preterm labor is greatest concern
  and may require perioperative monitoring and
  tocolysis
• postoperative pain management without sedation
• aid in early Dx. and Tx. of preterm labor
• assist with early mobilization
• ? prevent thromboembolic complications.