25 Questions
What is the number one goal when assessing a pregnant patient?
Ensuring good maternal care
Which organ system is impacted the most during pregnancy?
Cardiovascular system
What is a common physiological change in the respiratory system during pregnancy?
Increase in respiratory rate
Which of the following liver enzymes increases during pregnancy?
AST, ALT
What happens to renal blood flow during pregnancy?
Increases by 60%
Which of the following statements about cardiac output during pregnancy is true?
Stroke volume increases by 25-35%
How many ml/min of blood flow is delivered to the uterus during pregnancy?
700 ml/min
What percentage of the uterine blood flow perfuses the intervillous space (placenta)?
80%
What is the leading cause of maternal death worldwide, including in the United States?
Maternal hemorrhage
Which trimester is considered the safest for anesthesia during pregnancy?
Second trimester
What is the significance of fetal heart rate variability after 25 weeks of pregnancy?
It indicates fetal wellbeing
Regional anesthesia is always preferred during surgery in pregnancy.
True
The decision to monitor FHTs during surgery should include a conversation with OB provider and surgeon.
True
Your patient is pregnant and has been NPO since yesterday morning. You can treat this patient as a true NPO.
False
Increased intravascular volume during pregnancy results in a 20-30% increase in erythrocyte volume.
True
Respiratory changes in pregnancy include a decrease in tidal volume (TV).
False
Plasma cholinesterase levels during pregnancy increase by 30%.
False
The production of alkaline phosphate by the placenta results in decreased liver enzyme levels during pregnancy.
False
Cardiac output decreases by 35% during pregnancy due to an increased systemic vascular resistance (SVR).
False
Uterine blood flow during pregnancy has significant autoregulation
False
Cholecystectomy or appendectomy are examples of elective surgeries commonly performed during pregnancy.
False
All general anesthetic drugs have been found to cause an increase in birth defects in pregnant women
False
Fetal heart rate monitoring should begin after 10 weeks of pregnancy
False
Increased levels of progesterone during pregnancy lead to increased gastric emptying
False
All general anesthetics cross the placenta.
True
Study Notes
Physiological Changes in Pregnancy
- Almost every organ system is impacted by pregnancy, with changes beginning in the first trimester.
- Pharmacokinetics (PK) and pharmacodynamics (PD) are both impacted.
- Hormone activity increases, leading to:
- Increased maternal metabolic demands and biochemical alterations.
- Mechanical effects of a gravid uterus.
Cardiovascular Changes
- 35-45% increase in intravascular volume.
- 45-55% increase in plasma volume.
- 20-30% increase in erythrocyte volume.
- 40-50% increase in cardiac output.
- 25-35% increase in stroke volume (SV).
- 15-25% increase in cardiac output (CO).
- 20% decrease in systemic vascular resistance (SVR).
- 35% decrease in pulmonary vascular resistance (PVR).
- Supine hypotension develops.
Respiratory Changes
- 45-50% increase in minute ventilation (MV).
- 40-45% increase in tidal volume (TV).
- 0-15% increase in respiratory rate (RR).
- 0-5% decrease in total lung capacity (TLC).
- No change in vital capacity (VC).
- 20% decrease in functional residual capacity (FRC).
- 20% increase in oxygen consumption.
- Upper airway capillary engorgement.
Hepatic and Biliary Changes
- AST, ALT, and bilirubin increase to upper limits of normal.
- Plasma protein concentrations decrease.
- Plasma cholinesterase levels decrease by 30%.
- Placenta production of alkaline phosphate levels results in double the normal value, leading to gallbladder issues.
Renal Changes
- 60% increase in renal blood flow.
- Increased clearance of creatinine, urea, and uric acid.
- Upper limits of BUN and Cr in pregnancy are 50% lower.
Ureteroplacental Physiology
- 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 (e.g., cholecystectomy, appendectomy, maternal trauma, cancer, fetal procedures).
- Maternal hemorrhage is the number one cause of maternal death worldwide (including the US).
- Up to 2% of pregnant patients will require surgery.
Anesthesia Toxicity
- All general anesthetic drugs cross the placenta.
- No studies found 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.
Preoperative Considerations
- Consultation with OB provider, always.
- Maternal coexisting disease.
- Pregnancy overlaying the coexisting disease.
- New disease of pregnancy.
- Capabilities of the facility.
- Progression of the pregnancy.
- Refer to OB provider.
Fetal Heart Rate Monitoring
- FHTs 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 (OB provider, surgeon, anesthesia provider).
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