Tocolytics & Uterotonics Part 1

Question 1

Tocolytics are administered to

Answer 1

delay delivery

administered concomitantly with the corticosteroids

Question 2

Tocolytics are administered to reduce neonatal risk of

Answer 2

respiratory distress syndrome
intraventricular hemorrhage
necrotizing enterocolitis
perinatal death

Question 3

The onset of tocolytics and maximum benefit is

Answer 3

18 hours onset

max benefit 48 hours

Question 4

Tocolytic drugs include

Answer 4

magnesium sulfate
calcium channel blockers
Beta adrenergic agonists
nitric oxide donors 
cyclooxygenase inhibitors
oxytocin antagonists

Question 5

Tocolytics inhibit labor by

Answer 5

generation or alteration of intracellular messengers or inhibiting synthesis or block action of a myometrial stimulant

Question 6

Magnesium sulfate results in relaxation of

Answer 6

vascular, bronchial, and uterine smooth muscle

Question 7

The mechanism of action of magnesium sulfate is

Answer 7

alter calcium transport & availability for muscle contraction
compete with intracellular calcium; reducing myometrial contractility
hyperpolarization of the plasma membrane leads to inhibition of MLCK activity as magnesium

Question 8

Magnesium sulfate may be used to treat

Answer 8

preeclampsia

Question 9

Describe why magnesium sulfate can be used to treat preeclampsia.

Answer 9

relaxes vascular smooth muscle decreasing SVR & BP
anticonvulsant
decreases fibrin deposition, improving circulation to visceral orgas

Question 10

Neonatal side effects of magnesium sulfate include

Answer 10

hypotonia

respiratory depression

Question 11

Describe administration of magnesium sulfate.

Answer 11

loading dose of 4 to 6 g over 20-30 minutes
infusion of 1 to 2 gm/hr
continued through delivery and up to 24 hours post delivery

Question 12

The therapeutic level of magnesium is

Answer 12

4 to 9 mEq/L

Question 13

Normal serum magnesium during pregnancy is

Answer 13

1.8-3 mg/dL

Question 14

The tocolytic range of magnesium sulfate is

Answer 14

4 to 8 mg/dL

EKG changes: PQ lengthened; QRS widened

Question 15

The anticonvulsant range for magnesium sulfate is

Answer 15

7 to 9 mg/dL

Question 16

Tendon reflexes are abolished at levels of

Answer 16

10 to 12 mg/dL with magnesium sulfate

Question 17

Respiratory depression occurs at levels of

Answer 17

> 12 mg/dL of magnesium

Question 18

SA & AV blocks, & respiratory arrest occurs at

Answer 18

15-20 mg/dL

Question 19

Apnea occurs at

Answer 19

18 mg/dL

Question 20

Cardiac arrest occurs at

Answer 20

25 mg/dL

Question 21

Magnesium sulfate can result in

Answer 21

decreased blood pressure
antagonism of a-agonist
potentiation of neuromuscular blocking drug

Question 22

Side effects of magnesium sulfate include

Answer 22

CNS depression
skeletal muscle weakness
sedation 
vascular dilation, transient hypotension 
flushing 
palpitations

Question 23

Treating magnesium sulfate overdose includes

Answer 23

discontinue infusion
secure airway
IV administration of calcium chloride
diuresis

Question 24

Anesthetic implications of magnesium sulfate include

Answer 24

exaggerated hypotension after administration of epidural or general anesthesia
succinylcholine dose is not reduced for intubation- reduce maintenance doses of nondepolarizing muscle relaxants
symptomatic hypocalcemia & respiratory compromise have occurred in cases of myotonic dystrophy

Question 25

The following calcium channel blockers is commonly used because it can be given PO or sublingually:

Answer 25

Nifedipine

Question 26

The mechanism of action of calcium channel blockers include

Answer 26

block the influx of calcium ions through the cell membrane
block release of calcium from the SR
inhibit calcium-dependent myosin light-chain kinase-mediated phosphorylation- leads to myometrial relaxation
also act on potassium channels

Question 27

When calcium channel blockers are used as a tocolytic, birth is delayed between

Answer 27

2 and 7 days

Question 28

Side effects of calcium channel blockers include

Answer 28

hypotension 
dyspnea 
pulmonary edema 
tachycardia
headache

Question 29

Calcium channel blockers should not be used concomitantly with

Answer 29

magnesium sulfate

-enhance neuromuscular blocking effects affecting respiratory & cardiac function

Question 30

Anesthetic implications of calcium channel blockers include

Answer 30

expect hypotension with administration of neuraxial or general anesthesia
potential uterine atony that may be refractory to oxytocin and prostaglandins

Question 31

Stimulation of ________ results in smooth muscle relaxation.

Answer 31

B2 receptors

Question 32

Beta agonists are used to

Answer 32

inhibit myometrial contractility

increase in progesterone production- limits the spread of contractile impulses

Question 33

Common beta 2 agonists include

Answer 33

terbutaline

Question 34

Side effects of beta 2 agonists include

Answer 34

maternal & fetal tachycardia
dysrhythmias
ischemia 
hypotension 
headache
hyperglycemia 
hypokalemia 
increased plasma renin & vasopressin

Question 35

Hazards of beta 2 stimulation include

Answer 35

neonatal hypoglycemia
fetal tachycardia
increased blood sugar & insulin levels in the mother

Question 36

Hypotension from beta 2 agonists should be treated with

Answer 36

phenylephrine or ephedrine

Question 37

Anesthetic implications of beta 2 agonists include delay anesthesia for

Answer 37

60 minutes to allow the heart rate to decrease
-if not possible, all drugs that increase HR should be avoided
-ketamine, atropine, glyco, thiopental, pancuronium, etomidate
monitor IV administration due to risk of fluid overload and pulmonary edema

Question 38

_______ is more likely to delay delivery than nitric oxide donors

Answer 38

magnesium sulfate

Question 39

Side effects of nitric oxide donors include

Answer 39

maternal hypotension

headache

Question 40

Nitric oxide donors work by

Answer 40

increasing cyclic guoanosine monophosphatase (cGMP)

inactivates myosin light chain kinases causing smooth muscle relaxation