Obstetrics

Question 1

What happens to cardiac output during pregnancy? How does it change from fetal development until birth of the child? What factors influence the initial change in CO? What factors influence the dramatic change after labor? What can this mean for a mom with a history of heart problems, then?

Answer 1

Cardiac output increases in pregnancy due to an increase in stroke volume (increase blood volume) and an intrinsic increase in HR. It is increased by about 40% throughout pregnancy due to these factors.

Immediately after delivery CO increases as much as 80% due to blood volume and the now contracted uterus.

The increased demands on the heart associated with pregnancy can place a mom with heart disease at risk for heart failure.

Question 2

Does Hct increase or decrease with pregnancy? Does this lead to anemia? Why or why not?

Answer 2

Hct actually increases, but d/t the increase in blood volume a relative dilutional anemia exists.

Question 3

What happens to SVR during pregnancy? Why?

Answer 3

SVR and PVR decrease to promote perfusion

Question 4

What happens to MAP during pregnancy? Explain why

Answer 4

MAP remains relatively constant due to increased CO and decreased SVR

Question 5

What is average blood loss for a vaginal delivery? Uncomplicated Csection?

Answer 5

Vaginal: 500 ml
Csection: 750-1000 ml

Question 6

What is Aortocaval compression? What steps should be taken to avoid this complication when patients are supine?

Answer 6

Gravid patients lying supine may allow the uterus to compress the inferior vena cava and the aorta reducing blood return to the heart and blood flow to the uterus. This in return can reduce cardiac output and lead to hypotension and poor uterine perfusion.

Left uterine displacement. Place a ramp on the patients RIGHT side at 15 degrees to displace the uterus to the left

Question 7

Speak to the clotting situation for the parnutrient: What happens to coag factors? What happens to fibrinogen? What does all this mean for the parturient in terms of clotting?

Answer 7

Both. They are hypercoagable as coag factors and fibrinogen increase. This, however, is accompanied by increased fibrinogen breakdown. Overall, moms are considered to be hypercoagulable and at increased risk for clotting.

Question 8

What happens to platelets in the parnutrient? Why? What does this put the mom at risk for?

Answer 8

Platelet levels may decrease due to a number of possible factors including dilution and accelerated platelet breakdown. Usually this throbmobcytopenia is not a problem and considered normal with pregnancy. As a general rule of thumb practitioners may refuse to place epidural catheters if platelet values drop below 100K

Question 9

What makes parturients more susceptible to airway complications? What are the concerns?

Answer 9

Engorgement of the mucosa d/t increase in blood volume can lead to a higher malampati score, a narrowed glottic opening, and increased risk of bleeding with instrumentation

Question 10

How does pregnancy effect the following respiratory considerations: oxygen consumption, respiratory rate, tidal volume, minute ventilation, PaCO2, FRC, ERV, RV

Answer 10

O2 consumption: increased
RR: increased 
Minute Ventilation: increased
Tidal Volume: increased 
PaCO2: decreased 
FRC: decreased 
ERV: decreased
RV: decreased

Question 11

Why are FRC, ERV, and RV decreased in pregnancy? In terms of respiratory pathophysiology how can this be thought of as?

Answer 11

Due to upward displacement of the diaphragm restricting the lungs. It can be thought of as restrictive disease (not letting air in)

Question 12

What effect does progesterone have on MAC for anesthetics and dosing of local anesthetics both peripherally and neuroaxially?

Answer 12

MAC is decreased by 30-40%

Local anesthetic dosing is reduced as nerves are more sensitive to locals

Neuroaxial dosages are reduced d/t engorgement and reduction in the neuroaxial space increasing spread of the local both in the epidural and subarachnoid space

Question 13

What are the three considerations that make parturients a higher risk for aspiration? What causes these risks to occur?

Answer 13

Increased gastric volume d/t slow motility
Decreased pH of gastric content d/t gastrin
Decreased LES tone d/t progesterone

Question 14

At what point in pregnancy are parturients considered an increased aspiration risk and RSI with a secured and protected airway advised? At what point is the risk normalized?

Answer 14

Beginning in the 2nd trimester.

Question 15

What happens to GFR in pregnancy? Why does this occur?

Answer 15

GFR is increased d/t an increase in CO.

Question 16

Describe blood flow to the uterus in pregnancy (autoregulation, %CO,

Answer 16

There is NO autoregulation and thus it is dependent on a maternal MAP.
It is 10% of cardiac output.

Question 17

What are disadvantages to IV analgesics for laboring parturients?

Answer 17

Typically provides subpar pain relief
Leads to maternal and fetal respiratory depression
Associated with nausea and vomiting in the face of a lowered LES tone —> aspiration risk

Question 18

Will the following opioid analgesics cause respiratory depression in the fetus? (Meperidine, Morphine, Fentanyl, Ketamine, Remifentanil)

Answer 18

All of them can cause respiratory depression in the neonate if administered in utero

Question 19

Describe each stage of labor in regards to vaginal changes, delivery process, and analgesia needs (stage 1, stage 2, stage 3)

Answer 19

Stage 1: dilation and effacement from 1-9 cm, pain is typically T10-L2
Stage 2: complete dilation (10 cm) until delivery of the fetus, pain is T10-L2 and S2-S4
Stage 3: delivery of the placenta

Question 20

What is fetal heart rate variability? What is a normal FHR? What is normal variability (mild, moderate, marked)?

Answer 20

When a fetus is well oxygenated there will be variability in the fetal heart rate from 110-160 bpm. Variability is an assurance of fetal well being. Variability is described as mild (< 5bpm variability), moderate (6-24 bpm variability), and marked (25+ bpm variability)

Question 21

What are the advantages and disadvantages of Bupivicaine for epidural anesthesia

Answer 21

Produces more sensory then motor block (differential blockade); ADVANTAGE
Associated with more severe cardiotoxicity with LAST

Question 22

What are the advantages and disadvantages of lidocaine for use in parturients?

Answer 22

It has a quick onset with dense block for Csection; ADVANTAGE

The dense block is not ideal for vaginal delivery; DISADVANTAGE

Lidocaine is associated with potential neurotoxicity, cauda equina syndrome, and transient neurological symptoms when administered in the subarachnoid space (spinal) and for this reason it is often avoided for spinal anesthesia; DISADVANTAGE

Question 23

What unique phenomenon must be considered with the use of morphine and chloroprocaine

Answer 23

It has been show to reduce the effectiveness of neuroaxial morphine

Question 24

What is a common “test dose” for placement of an epidural catheter in obstetric anesthesia? What is the idea behind this test dose?

Answer 24

45 mg of lidocaine (3 cc of 1.5%) in 1:200,000 epinephrine. It is a means of assessing if the catheter is intrathecal or intravascular. Intrathecal will create a dense lower extremity block (undesired) and intravascular will created an increase in HR and possibly early signs of systemic toxicity (lip numbness, metallic taste, ringing in ears). In pregnant patients an increase in HR with bolus test dose is non-specific due to contractions and pain.

Question 25

What is the advantage of adding an opioid to an epidural or spinal block? What are the disadvantages?

Answer 25

Opioids allow lower concentrations of local anesthetic, thus creating less motor blockade, while maintaining effective analgesia.

Question 26

What are indications that an epidural catheter may have migrated into the intrathecal space? What about the intravascular space?

Answer 26

Intrathecal —> If motor block becomes dense, sensory block remains adequate, and segmental spread less distinct

Intravenous —> sensory block lost and possible signs of system toxicity (though low concentration epidural bags make this unlikely

Question 27

What are common solutions for epidural anesthesia (Bupivicaine and Ropivicaine)? What is a common rate?

Answer 27

Bupivicaine: 0.0625% - 0.125% w/ 1-3 mcg of fentanyl

Ropivicaine: 0.1% - 0.2% w/ 1-3 mcg of fentanyl

Rate is 8-12 ml/hr with bolus interval

Question 28

What are common side effects of neuroaxial opioid administration?

Answer 28

Respiratory depression, pruritus, urinary retention, nausea

Question 29

What is a “subdural injection” during epidural? What are the signs and symptoms? How can it be avoided? What is the treatment?

Answer 29

Placement of the catheter between the dura and the arachnoid (subdural). Spread will occur within 5-15 minutes to cause hypotension, respiratory compromise, and/or unconsciousness.

It can not be avoided. Treatment involves support: stop infusion, provide hemodynamic support, intubate and respiratory support if needed.

Question 30

Describe the two common uses of Mg Sulfate infusion in the obstetric population. What are the therapeutic levels for the therapy?

Answer 30

Tocolytic: used to stop/slow uterine contractions in preterm pregnancy. Therapeutic level is 4-8 mg/dL

Anti-convulsant: used to prevent seizures in cases of severe pre-eclampsia. Therapeutic levels are 8-10 mg/dL

Question 31

What are the common side effects of Mg Sulfate infusion that should be monitored for?

Answer 31

Pulmonary Edema
Hypotension
Loss of Reflexes
Muscle Weakness
CNS Depression

Question 32

How does Mg Sulfate work as a Tocolytic? What about as a treatment for pre-eclampsia?

Answer 32

Mg Sulfate reduces the amount of Ca for uterine contraction

It is a CNS depressant

Question 33

Describe what is observed at the following Mg levels: 1-3, 4-8, 8-10, 10+, 18+

Answer 33

1-3: normal Mg blood level
4-8: useful as a tocolytic 
8-10: useful as an anticonvulsant
10+: deep tendon reflexes are suppressed
18+: respiratory depression

Question 34

What is the use of betamethasone in pregnancy for the neonate? How long does it take before it begins to take effect with benefits?

Answer 34

It is given to hasten the lung development of the neonate in cases of possible premature labor. It takes 8-48 hrs before results will be beneficial.

Question 35

What class of drug is Terbutaline? What is it used for? What are common side effects? Why has it fallen out of favor?

Answer 35

It is a beta-agonist used as a tocolytic. Common side effects include transient low blood sugar and hypokalemia. It also causes fetal tachycardia as it crosses the placenta. It has fallen out of favor d/t fetal tachycardia and its lack of efficacy as a tocolytic.

Question 36

What must be taken into consideration in regards to the following IV pharmacological agents given concurrently with a Mg Sulfate infusion…

• Depolarizing Muscle Relaxant
• Non-Depolarizing Muscle Relaxant
• Alpha Agonists (phenylephrine, ephedrine, etc)

Answer 36

All muscle relaxants will be potentiated by Mg; this means smaller doses are needed to elicit muscle relaxation

Alpha agonists efficacy is decreased; it may take more then usual to elicit desired effects when a Mg Sulfate infusion is in use.

Question 37

Describe Placenta Previa, Placenta Accreta, Placenta Precreta, and Placenta Increta

Answer 37

Placenta Previa: the placenta covers the cervical os, this leads to painless vaginal bleeding, and depending to the severity of cervical os coverage a c-section may be indicated. Patients are at a higher risk for sudden rupture and bleeding and higher post-partum bleeding.

Placenta Accreta: the placenta is adhered to the myometrium and placenta delivery results in an increase in hemorrhage and bleeding.

Placenta Precreta: the placenta is adhered into the myometrium and placenta delivery results in an increase in hemorrhage and bleeding.

Placenta Increta: the placenta is adhered through the myometrium and placenta delivery results in an increase in hemorrhage and bleeding. Bleeding may be so intense and fast that a hysterectomy in the face of massive blood infusion is indicated

Question 38

What is placental abruption? What are the signs and symptoms? What are complications of abruption? What disease states are most likely to lead to abruption?

Answer 38

When the placenta tears away from the uterine and internal bleeding occurs. Signs and symptoms may include abdominal pain, loss of positive fetal assurance d/t hypoperfusion, external bleeding may or may not be noted. Parturients with pre-eclampsia or a history of uncontrolled HTN are more likely to have placental abruption.

Question 39

What is diagnostic for pre-eclampsia (Mild and Severe)

Answer 39

Mild is new onset HTN and proteinuria (>3g) at 20+ weeks gestation, other signs and symptoms are rare if present

Severe is BP >/= 160 mm Hg and proteinuria >5g. Other signs and symptoms may include visual disturbances, RUQ pain, headache, thrombocytopenia, etc.

Question 40

When should BP management be initiated for a mom diagnosed with pre-eclampsia? What is the aim of this management? When should Mg Sulfate infusion be initiated? Why? What is the therapeutic value?

Answer 40

BP management should be administered when BP exceeds 160 systolic or 110 diastolic. This is to reduce occurrences of thrombolitic stroke and/or decreased placental perfusion.

Mg Sulfate is initiated with severe pre-eclampsia to reduce chances of seizure. A therapeutic value is 8-10 mg/dL

Question 41

How is Mg toxicity treated?

Answer 41

With 10% calcium gluconate (10 ml)