Obstetrics Flashcards
When is maternal cardiac output the highest?
Immediately following delivery: this is because venous compression is relieved, there is some auto transfusion from uterine contraction, and there is no longer fetal dependence on mother’s circulation
It will fall rapidly and be back to normal around 2 weeks
What are the two hemodynamic parameters that either do not change, or decrease in pregnancy?
CVP remains the SAME, and venous capacitance increases, meaning that SVR DECREASES. Everything else, including HR, SV, volume, plasma volume, RBC mass increase
What are the respiratory changes seen during ACTIVE LABOR?
- Increased MV due to Increased TV and RR
- Decreased PaCO2, leading to a L shift in the O2 dissociation curve
- Increased O2 consumption
- Decreased alveolar dead space due to an increase in CO
What are the two HR cutoffs for fetal bradycardia and their interventions?
- < 100 bpm: provide PPV
2. < 60 bpm: perform chest compressions at a rate of 3:1 (3 compressions, 1 breath)
What happens to coagulation factors in pregnancy? Which 2 are affected the most?
- Increase in factors
- Factor VII and fibrinogen are increased the most
- Resistance to protein C and levels of protein S decrease
- Factors XIII and XI, AT III and tPa decrease
What is the first line treatment for uterine atony? What treatment should you avoid in a patient with pre-eclempsia?
- Oxytocin given as a slow infusion. Do not give as a bolus or a rapid infusion, as this will cause uterine relaxation
- Avoid methylergotamine in patients with pre-eclempsia, as this causes massive vasoconstriction and can worsen HTN
What are the signs of amniotic fluid embolism?
Cardiogenic shock, consumptive coagulopathy, pulmonary HTN, and fetal bradycardia
What intervention should you use for cerclage placement with bulging cervix vs. prophylactic cerclage?
- Cerclage with bulging cervix requires uterine relaxation –> perform a GA, this will relax the uterus
- Prophylactic cerclage would be best performed under neuraxial technique (aka Spinal)
What places a person at a higher risk for PDPH?
Female gender
What mediates FHR variability?
PS tone
What causes early, late, and variable decelerations?
- Early: benign finding, due to compression of the head
- Late: due to hypoxia, seen with placental insufficiency
- Variable: due to umbilical cord compression –> the relationship to the contraction is variable
What factor is increased in pre-eclempsia?
- Thromboxane A2
What determines the low placental transfer of Bupivicaine?
High protein binding
What values indicate an AKI in a pregnant woman?
Serum Cr > 0.8 mg/dl
BUN > 13
What are the respective blocks available for stage 1 or stage 2 labor?
- Stage 1: Paracervical block – though this can lead to fetal bradycardia
- Stage 2: Pudendal block
What are the two placental abnormalities associated with Breech presentation?
- Cornual placenta
2. placenta previa
Describe the risks and benefits of performing a CS vs. a vaginal birth.
- CS: Decreased risk of INITIAL uterine rupture and maternal hemorrhage
- However, CS has more risks and a longer hospital stay than vaginal births
What is the MOA of Terbutaline?
B2 agonist that binds to the uterine muscle to activate adenylyl cyclase, which leads to decreased Ca
- can cause tachycardia and pulmonary edema
What medication is used to facilitate fetal version, vaginal delivery of breech kiddo, or removal of retained placental contents?
Nitroglycerine
What two therapies are recommended for pre term labor?
- Corticosteroids: reduces morbidity and mortality
2. Magnesium: neuroprotective in kids in pre term labor
What are some causes of Polyhydramnios?
Duodenal atresia, TE fistula, inhibition of fetal swallowing
What effect does lisinopril have on amniotic fluid production?
It causes oligohydramnios
What metabolic derangement is seen with high dose Oxytocin use? Why?
Hyponatremia. This is because high doses of oxytocin lead to decreased renal excretion of fluid. This fluid overload then stimulates natriuresis.
What is the major disadvantage to doing a paracervical block during labor?
It causes fetal bradycardia, possibly due to vasoconstriction of local anesthetic injection
What is the electrolyte abnormality seen with Terbutaline?
Hypokalemia
What gas is LEAST likely to cause uterine relaxation in a GA for a pregnant woman?
N20
What effect does Nitrous Oxide have on pulmonary pressures?
It increases PVR
What is the structure of Glycopyrrolate? Does it cross the placental barrier?
- Quaternary amine
- It does NOT cross the placenta
- In general, things that cross the BBB will cross the placental barrier
What are the characteristics of drugs that cross the placental barrier?
- Small
- Uncharged
- Unionized
- Low protein binding
- High concentration of free drug
What will PTT and PT show in Antiphospholipid antibody syndrome?
- PTT: prolonged
2. PT: normal
What is the most common cause of postpartum hemorrhage?
Uterine atony
What are the criteria that indicate severe pre-eclampsia?
- BP > 160/110
- Thrombocytopenia
- Liver impairment
- Renal impairment
- CNS or visual disturbances
- Pulmonary edema
What are the criteria to diagnose Pre-eclampsia?
BP > 140/90 on two separate occasions in a pregnant woman > 20 weeks who did NOT have HTN before
What two agents are used for uterine relaxation in Inversion? How about for retained placenta?
- For inversion: use magnesium and terbutaline
2. For retained placenta: use NG
What effect does neuraxial anesthesia have on temperature?
It causes vasodilation below the level of the block. This leads to a redistribution of blood that lowers the core temperature. Additionally, the levels below the block cannot sense the cold, and the threshold for shivering is lowered. When patients start to shiver, they shiver above the level of the block, which cannot generate enough heat to cover the levels below the block.
Non-thermogenic shivering is also a possibility. AKA is not related to the actual core temperature
What effect does Terbutaline have on fetal insulin levels?
Causes hyperinsulinemia: This is because the mother is hyperglycemic and the glucose transfers to the fetus, but the insulin does not. The fetus then compensates by increasing production of insulin
What is the most common cause of maternal mortality in labor?
Cardiovascular diseases
What levels are targeted when doing neuraxial analgesia for a C-section?
T4-S4
What is the treatment for pruritic associated with neuraxial opioids?
Nalbuphine
What is the MOA of Ritrodine?
B2 agonist used for uterine relaxation. It increases uterine blood flow
When might prostaglandins be CI in patients with uterine atony?
If they have asthma. Carboprost can lead to increased PVR, that can lead to pulm HTN and bronchoconstriction. In general, prostaglandins cause bronchoconstriction
What pH and lactate levels define fetal acidemia?
- pH < 7.20
2. Lactate > 4.8
What value on an ABG is increased in a pregnant woman vs. a healthy woman?
PaO2: this is due to increased MV
According to the ASA, what is the difficult airway algorithm?
If the baby is not in distress, wake up the patient.
If the baby is distressed and you CAN mask ventilate, either continue masking, or throw in an LMA. If you CANNOT mask, put in an LMA or perform a surgical airway.
When is vWD a CI to neuraxial anesthesia?
If disease is severe (and sometimes moderate can be CI). It is all based upon Factor VIII levels, so a patient should undergo lab testing prior to neuraxial anesthesia if it is not an emergency
What are the cut offs for APGAR scores?
< 3 means necessary resuscitation
4-7 moderate, requires observation
8-10 is normal
When is it safest to perform non-obstetric surgery in a pregnant woman?
In the second trimester. No anesthetic technique has been shown to reduce the risk of pre-term labor or miscarriage
