Tocolytics and Uterotonics

Question 1

What interventions are used to prevent and treatment postpartum hemorrhage?

Answer 1

uterogenics (oxytocin, methylergonovine, prostaglandins, misoprostal

Question 2

Why are ergot alkaloids (Methergine) not administered IV?

Answer 2

because of their potent vascular effects, profound hypertension, nausea and vomiting, cerebral hemorrhage

Question 3

What is the dose and route of administration for Methergine?

Answer 3

0.2 mg IM, can be repeated 15-20 minutes, total dose 0.8

Question 4

What do ergot alkaloids cause besides uterine contraction?

Answer 4

increase in blood pressure, central venous pressure, pulmonary capillary wedge pressure

Question 5

What can prostaglandins cause besides uterine contraction?

Answer 5

nausea, bronchospasm, increased pulmonary vascular resistance

Question 6

How is Hemabate administered?

Answer 6

IM or directly into uterine muscle

Question 7

How is preeclampsia defined?

Answer 7

systolic HTN of 140mmHg or higher or diastolic of 90mmHg or higher after 20weeks gestation with proteinuria

Question 8

What is the one way to end preeclampsia?

Answer 8

delivery

Question 9

Risk of postpartum hemorrhage interventions

Answer 9

large bore IV, has volume resuscitation, have fluid warmer available, T&C, CBC, coags

Question 10

In terms of preeclampsia what can be done to enhance fetal lung maturity if no severe features are occurring?

Answer 10

corticosteroid administration

Question 11

Magnesium sulfate MOA

Answer 11

alter calcium transport and availability for muscle contraction, competes with calcium reducing myometrial contractility, hyperpolarization leads to inhibition of MLCK activity = relaxation of vascular, bronchial, uterine smooth muscle, vasodilation

Question 12

Magneisum sulfate Indications

Answer 12

preeclampsia (decreases SVR and BP, anticonvulsant, decreases fibrin deposition improving circulation to visceral organs)

Question 13

Magnesium sulfate Administration

Answer 13

Loading dose 4-6 grams IV in 50mL over 20-30minutes

Infusion 1-2g/hr, continued thru delivery up to 24 hours post delivery

Question 14

Therapeutic Magnesium level

Answer 14

4-9 mEq/L (normally 1-3)

Question 15

Magnesium sulfate Side effects

Answer 15

transient hypotension, sedation, skeletal muscle weakness, CNS depression

Question 16

Magnesium sulfate overdose

Answer 16

discontinue infusion, secure the airway, IV CaCl, diuresis

Question 17

What do tocolytics do?

Answer 17

relax the uterine muscle, slow down delivery

Question 18

What are tocolytics concomitantly administered with?

Answer 18

corticosteroids for lung protection of neonate, prior to 33 weeks gestation, maximum benefit 48 hours

Question 19

Types of tocolytics

Answer 19

magnesium sulfate, calcium channel blockers, b-adrenergic agonists, nitric oxide donors, cyclooxygenase inhibitors, oxytocin antagonists

Question 20

neonatal side effects of magnesium sulfate

Answer 20

hypotonia, respiratory depression (RARE)

Question 21

What can happen when serum magnesium is >12mg/dL

Answer 21

respiratory depression

Question 22

what can happen when serum magnesium is 25 mg/dL

Answer 22

cardiac arrest

Question 23

What can happen when serum magnesium is 7-9mg/dL

Answer 23

anticonvulsant

Question 24

What can happen when serum magnesium is 10-12mg/dL

Answer 24

tendon reflexes abolished

Question 25

what can happen when serum magnesium 15-20mg/dL

Answer 25

SA and AV blocks, respiratory arrest

Question 26

What calcium channel blocker do we use as a tocolytic and why?

Answer 26

nifedipine, it can be given PO or sublingually

Question 27

Mechanism of action of Nifedipine

Answer 27

block influx of Ca2+, block release of Ca2+ from SR, inhibit Ca2+-dependent MLCK mediated phosphorylation

Question 28

How long can birth be delayed for with use of nifedipine?

Answer 28

2-7 days

Question 29

Side effects of Nifedipine

Answer 29

hypotension, dyspnea, pulmonary edema, tachycardia, HA Avoid concomitant use with magnesium sulfate

Question 30

How do B2 agonists work?

Answer 30

stimulates B2 receptors causing smooth muscle relaxation, inhibit myometrial contractility, increase progesterone production

Question 31

what does progesterone cause?

Answer 31

histologic changes in myometrial cells that limit the spread of contractile impulses

Question 32

Which B2 agonist do we use the most?

Answer 32

Terbutaline

Question 33

What are the hazards of B2 stimulation?

Answer 33

- increased blood sugar and insulin levels in mom | - neonatal hypoglycemia and tachycardia

Question 34

Side effects in mom and fetus with B2 agonists

Answer 34

``` vasodilation tachycardia dysrhythmias ischemia hypotension pulmonary edema HA hyperglycemia hypokalemia increased plasmin renin and vasopressin ```

Question 35

How long should anesthesia be delayed for with B2 agonist administration if possible?

Answer 35

60 minutes to allow HR to come down if not possible don't give drugs to increase HR

Question 36

How should hypotension be treated with B2 agonist administration?

Answer 36

phenylephrine or ephedrine

Question 37

Which nitric oxide donor do we administer?

Answer 37

nitroglycerine

Question 38

How do nitric oxide donors work?

Answer 38

increasing cyclic guanosine monophosphate (cGMP), inactivates MLCK = smooth muscle relaxation

Question 39

Side effects of nitric oxide donors

Answer 39

HA, hypotension

Question 40

What does cyclooxygenase do?

Answer 40

converts arachidonic acid to prostaglandin h2 which enhance formation of myometrial gap junctions increasing available Ca2+

Question 41

How cyclooxygenase inhibitors work?

Answer 41

reduce prostaglandin levels by inhibiting COX enzymes from converting arachidonic acid = decreased uterine contraction

Question 42

Which nonselective COX inhibitor do we use?

Answer 42

Indomethacin

Question 43

Which COX-2 selective inhibitor do we use?

Answer 43

Celecoxib

Question 44

Anesthetic implications of COX inhibitors

Answer 44

platelet inhibition with nonselective COX inhibitors

Question 45

Which muscle relaxant is preferred for RSI with tocolytics?

Answer 45

Succinylcholine

Question 46

What do uterotonics do?

Answer 46

cause contraction

Question 47

What is the leading cause of postpartum hemorrhage?

Answer 47

uterine atony

Question 48

What intervention should be tried first post delivery for PPH?

Answer 48

fundal massage and then oxytocin

Question 49

What is oxytocin?

Answer 49

endogenous hormone produced by posterior pituitary gland that lowers the threshold for depolarization of uterine smooth muscle

Question 50

What synthetic oxytocin do we give?

Answer 50

Pitocin - octapeptide

Question 51

Pitocin administration

Answer 51

20-40 units/L over 15-20minutes post delivery as soon as cord is cut, also used prophylactically to reduce blood loss, never bolus

Question 52

Pitocin administration to induce labor

Answer 52

infusions at low controlled rates

Question 53

Side effects of pitocin

Answer 53

vasodilation or decreased SVR = hypotension and tachycardia

Question 54

2nd line of treatment for uterine atony

Answer 54

ergot alkaloids

Question 55

which ergot alkaloid do we use?

Answer 55

Methergine - synthetic, MOA is not clear

Question 56

Contraindications for ergot alkaloids

Answer 56

preexisting hypertension, PVD, ischemic heart disease

Question 57

what can we give if methergine is contraindicated or not effective?

Answer 57

prostaglandins (hemabate)

Question 58

MOA of Hemabate

Answer 58

increases myometrial calcium levels, increases MLCK activity = uterine contraction

Question 59

Administration of Hemabate

Answer 59

250 mcg IM or directly into myometrium, repeat every 15-30minutes, total dose 2mg

Question 60

Administration of Misoprostol

Answer 60

800-1000mcg, sublingual or buccal

Question 61

Use of Carboprost (prostaglandin) can result in __ with women with reactive airway disease

Answer 61

bronchospasm, Va/Q mismatch, hypoxemia