Health Assessment in Pregnancy and Anesthesia Quiz

Health Assessment in Pregnancy

• Pregnancy affects almost every organ system, with changes starting in the first trimester
• Maternal changes during pregnancy are critical to understand, with the number one goal being to take care of the mother
• Good maternal care is essential for good fetal care

Physiological Changes in Pregnancy

• Cardiovascular changes:
  • Increased intravascular volume (35-45%)
  • 45-55% increase in plasma volume
  • 20-30% increase in erythrocyte volume
  • Increase in cardiac output (40-50%)
  • 25-35% increase in stroke volume (SV)
  • 15-25% increase in cardiac output (CO)
  • Decrease in systemic vascular resistance (SVR) by 20%
  • Decrease in pulmonary vascular resistance (PVR) by 35%
• Respiratory changes:
  • Increased minute ventilation (MV) by 45-50%
  • Increased tidal volume (TV) by 40-45%
  • Respiratory rate (RR) increases by 0-15%
  • Total lung capacity (TLC) decreases by 0-5%
  • Vital capacity (VC) remains unchanged
  • Functional residual capacity (FRC) decreases by 20%
  • Oxygen consumption increases by 20%
• Hepatic and biliary changes:
  • Increased AST, ALT, and bilirubin levels to upper limits of normal
  • Decreased plasma protein concentrations
  • Decreased plasma cholinesterase levels by 30%
  • Placenta production of alkaline phosphate levels results in double the normal value, leading to gallbladder issues
• Renal changes:
  • Increased renal blood flow by 60%
  • Increased clearance of creatinine, urea, and uric acid
  • Upper limits of BUN and Cr in pregnancy are 50% lower

Uteroplacental Physiology

• Uterine blood flow increases from 100 ml/min to 700 ml/min (10% of CO)
• 80% of uterine blood flow perfuses the intervillous space (placenta) and the rest perfuses the myometrium (muscle)
• Uterine blood flow has minimal autoregulation

Surgery in Pregnancy

• Mostly limited to non-elective surgery
• Common reasons for surgery include cholecystectomy, appendectomy, maternal trauma, cancer, and fetal procedures (EXIT)
• Maternal hemorrhage is the number one cause of maternal death worldwide
• Up to 2% of pregnant patients will require surgery

Anesthesia in Pregnancy

• All general anesthetic drugs cross the placenta
• No studies found an increase in birth defects in women undergoing anesthesia while pregnant
• Small increase in risk for miscarriage or preterm delivery
• In general, the second trimester is the safest for anesthesia
• Regional anesthesia is always preferred

Preoperative Considerations

• Consultation with OB provider is always necessary
• Maternal coexisting disease should be considered
• Pregnancy can overlay the coexisting disease or create new diseases
• Capabilities of the facility should be assessed
• Progression of the pregnancy should be considered
• Refer to OB provider for guidance

Fetal Heart Rate Monitoring

• Fetal heart rate (FHT) should be monitored after 18 weeks
• At 25 weeks, FHT variability is a sign of fetal wellbeing
• Decision to monitor FHTs during surgery needs to be a three-way discussion between OB provider, surgeon, and anesthesiologist