Maternal/Fetal Uterotonics

Question 1

C-section goals

4

Answer 1

• stable hemodynamics
• limit cardiac/resp depressant drugs that cross placenta
• birth of a healthy baby
• minimize bleeding

Question 2

The Maternal-Fetal exchange of substances and drugs occurs by diffusion if the molecular weight is _________?

Answer 2

< 1000 Daltons

Question 3

Pregnancy induced CV changes?

4

Answer 3

• ↑ Blood volume
• ↑ Cardiac Output
• Supine HoTN
• ↓ Vascular resistance

Question 4

When and how does maternal intravascular fluid volume begin to change?

Answer 4

Increases in the first trimester

Question 5

Increases in maternal intravascular fluid are caused by? End result?

Answer 5

• ↑ Renin, Angiotensin, Aldosterone
• Na+ & H2O reabsorption

Question 6

What causes the endocrine changes to intravascular fluid?

Answer 6

Induced by progesterone

Question 7

How do plasma proteins change due to plasma volume changes?

Answer 7

↓ Plasma proteins (dilutional)

Question 8

How much does plasma volume & RBCs change by gestation?

Answer 8

• ↑ Plasma by 50%
• ↑ RBCs only by 25%

Question 9

What Hgb value represents anemia during pregnancy at any time?

Answer 9

< 11g/dL

Question 10

Why does physiologic anemia not cause a decrease in O2 delivery?

Answer 10

↑ CO

DO2 = CO(Hgb x SpO2 x 1.34) + (PaO2 x 0.003)

Question 11

How much quantitively does intravascular fluid increase by term?

Answer 11

1,000-1,500 mL

Question 12

Averge EBL for Vaginal delivery?

Answer 12

300-500mL

Question 13

EBL for C-Section?

Answer 13

800-1,000 mL

Question 14

What neat little trick does the uterus do to volume status after delivery?

Answer 14

Uterine contraction auto-transfuses blood compensating for acute loss

Question 15

What hematological change might be observed during pregnancy?

Answer 15

Mild Thrombocytopenia

Question 16

What value does platelet count not drop below? And what is the thrombocytopenia not associated with?

Answer 16

70,000/mcL

• Abnormal bleeding

Question 17

Why does mild thrombocytopenia occur during pregnancy?

Answer 17

• Hemodilution
• Accelerated platelet turnover

Question 18

Leukocytosis in pregnancy

Answer 18

Common, unrelated to infection

Question 19

What kind of coagulable state is pregnancy, usually?

Answer 19

Hypercoaguable

Question 20

Why is pregnancy hypercoaguable?

Answer 20

• Increased clotting
• Decreased fibrinolysis

Question 21

What and how do coagulation factors change during pregnancy?

Answer 21

• ↑ F.VII, VIII, X, vWF, & Fibrinogen
• ↓ Protein S & ATIII

Question 22

Normal non-pregnant Uterine blood flow?

Answer 22

100mL/min

Question 23

Uterine blood flow @ term gestation?

Answer 23

700mL/min

Question 24

What does the Uterine blood flow @ term gestation represent hemodynamically?

Answer 24

~10% of CO

Question 25

Uterine perfusion pressure can be decreased by:

Answer 25

* Maternal HoTN 2/2 hypovolemia * Aortocaval compression * ↓ SVR for GA or Neuraxial anesthesia * decreased uterine venous pressure (supine vena caval compression, prolonged uterine contracation, Valsalva during pushing)

Question 26

Hypocapnia affect on uterine blood flow and fetus

Answer 26

Extreme hypocapnia (<20 mmHg) from hyperventilation due to pain --> reduce uterine blood flow --> fetal hypoxemia and acidosis

Question 27

When **does** neuraxial blockade alter uterine blood flow?

Answer 27

In the presence of Maternal HoTN

Question 28

When does neuraxial blockade **NOT** alter uterine blood flow?

Answer 28

In the absence of Maternal HoTN

Question 29

Which sympathomimetic is preferred in cases of Maternal HoTN? Why?

Answer 29

**Phenylephrine** * ↓ fetal acidosis * ↓ base deficit Than ephedrine

Question 30

What kind of hemorrhage has a higher incidence of coagulopathy relative to total blood loss?

Answer 30

Obstetric hemorrhage * When compared to surgical/trauma hemorrhage

Question 31

Oxytocin uses?

Answer 31

* Stimulates uterine muscle * Reduce/prevent uterine atony * ↓ hemorrhage in post-partum/abortion period

Question 32

Dose of Oxytocin to manage Uterine Atony? PPH?

Answer 32

* Atony: 1-3 units * PPH: 3-5 units

Question 33

What concern exists for a pregnant pt who previously received oxytocin?

Answer 33

Downregulation/desensitization of oxytocin receptor -> PPH & atony

Question 34

Oxytocin MoA

Answer 34

Binds to oxytocin receptor in myometrium -> ↑ intracelluar Ca2+ -> stimulates contractions

Question 35

Oxytocin dose/Half-life?

Answer 35

* 20-60 units/1L LR * Half-life: 1-6 min

Question 36

Methylergonovine MoA?

Answer 36

Direct action on α-adrenergic & 5-HT2 receptors -> ↑ uterine contraction forces/frequency

Question 37

Methylergonovine Dose/Half-lie?

Answer 37

* 0.2mg IM * Half-life: 3.4hr

Question 38

Contraindications/Caution for Methylergonovine?

Answer 38

HTN & Pre-eclampsia

Question 39

Carboprost MoA?

Answer 39

↑ myometrial concentrations of Ca2+ -> ↑ uterine contractions

Question 40

What kind of drug is Carboprost?

Answer 40

Synthetic Prostaglandin

Question 41

Carboprost Dose/Half-life?

Answer 41

Dose: 250mcg IM Half-life: ¯\ _ (ツ) _ /¯

Question 42

Contraindications/Cautions for Carboprost?

Answer 42

Asthma

Question 43

What kind of drug is Misoprostol?

Answer 43

Prostaglandin E1

Question 44

What does Misoprostol do?

Answer 44

Produce uterine contractions, duh

Question 45

Where does misoprostol get metabolized? Why?

Answer 45

Gut parietal cells * It goes in the butt

Question 46

Dose/Half-life of Misoprostol?

Answer 46

* 1000mcg Per Rectum (in the butt) * 20-40 min