Anesthesia for the Pregnant patient Undergoing Nonobstetric surgery

1. Anesthesia for the Pregnant patient Undergoing Nonobstetric surgery 경희의료원 마취통증의학과 R4 조 인배

2. 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?

3. 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 ↓.

4. 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

5. 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

6. 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?

7. 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

8. 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

9. 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(>2mg/kg) : may cause uterine hypertonus - inhalation agent : keep < 2.0 MAC (prevent maternal C.O. ↓)

10. 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

11. 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

12. 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 can’t be save with a viable fetus

13. 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 ↓

14. 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

15. 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.

18. 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.