OB Flashcards
Methergine causes arterial vasoconstriction by ___ stimulation and inhibition of ___ release.
alpha
endothelial derived relaxation factor
This drug used for blood pressure control in parturients is a combined alpha and beta antagonist with rapid onset and few neonatal complications (might see bradycardia).
Labetalol
Magnesium Sulfate
dose:
Onset:
Duration:
4 grams over 20 min, or 2-3 grams/hr infusion
onset: immediate
duration: 20-30 mins with good renal perfusion
Magnesium Sulfate – effects on anesthesia-related drugs:
Potentiates nondepolarizing and depolarizing NMBs (probably not enough to alter dose) (the inhibition of ACh release at the NMJ causes this)
In which order do we choose drugs for use in a hypertensive emergency for parturients?
labetalol –> hydralazine –> nipride
Misoprostol
dose:
onset:
half-life:
1-2 tablets buccal (in cheek) (200 mcg each) – can be given rectally and vaginally(by OB)
onset: rapid
half life: 20-40 mins
This drug used for blood pressure control in parturients is a potent vasodilator that decreases (preload/afterload), peripheral resistance (especially when used with volume repletion), maternal BP, and uterine vascular resistance to increase uterine blood flow.
Limiting side effects of this drug include maternal (bradycardia/tachycardia) (reflex sympathetic response to direct vasodilation), vomiting, and tremors.
Hydralazine
afterload
tachycardia
This drug is used in parturients as a venodilator. It decreases cardiac filling pressures by acting on capacitance vessels, and you may get reflex tachycardia.
Nitroglycerin
Methergine
dose:
onset:
duration:
0.2 mg IM every 2-4 hrs (max 5 doses)
onset: 2-5 mins
duration: ~3 hrs
Between Nipride and Nitro, which drug is preferred for use in parturients?
Nipride is preferred; Nitro may cause hypotensive “overshoot”
Which drug causes an increase in temperature that might initially lead the healthcare team to think the patient is experiencing MH?
Hemabate –> increases temperature possibly by 2 degrees (possibly due to effect on hypothalamic thermoregulation)
This drug is used in parturients for acute hypertensive crisis. It is a potent arteriolar dilator with a rapid onset and short duration. Maternal and fetal cyanide toxicity is a concern, but at low doses (5-10 mcg/kg/min) it is unlikely.
Nipride (Sodium nitroprusside)
Pitocin
dose
onset
DOA
10-40 U in 1000cc (1L) LR
onset: Immediate
duration: within 1 hr
WE NEVER GIVE IV BOLUS
What is our primary goal with the administration of Magnesium Sulfate in parturients?
What is a beneficial side effect?
Primary goal = prevent seizures
Beneficial side effect = decreased BP
Hemabate
dose
onset
DOA
250 mcg IM repeated every 15-45 mins (max 8 doses)
onset: immediate
duration: 2 hrs
How do you treat Magnesium Sulfate-induced magnesium toxicity?
Calcium gluconate 1 gram (given over 2 mins)
fluids
diuresis
O2
How does volume repletion help in the treatment of severe pre-eclampsia?
Intravascular repletion can improve the low CO.
When right and left cardiac filling pressures normalize, CI improves, maternal HR and SVR decrease, and fetal circulation improves.
why do we use Methergine?
1) Helps induce labor (by increasing motor activity/tone of the uterus) >arterial vasoconstriction)
2) Then helps the uterus stop bleeding post-delivery (alpha stimulation –> arterial vasoconstriction)Why do we give methergine?
Magnesium Sulfate effects:
- Mild vasodilator that decreases uterine activity to increase uterine blood.
- Decreases SVR
- Pulmonary Edema
- Dilates liver beds and kidneys to increase function,
Methergine (____________)
___ (Methylergonovine)
Pitocin (___)
___ (Oxytocin)
Hemabate (___)
___ (Carboprost)
Magnesium Sulfate s/e:
Can cause pulmonary edema, may be some correlation with chorioamnionitis
magnesium toxicity (monitor Mag levels, treat toxicity with calcium gluconate 1 gram over 2 min, fluids, diuresis, O2)
Crosses the placenta, so neonate may show signs of respiratory depression, apnea, and decreased tone
Magnesium plasma level that causes:
normal levels
Magnesium plasma level that causes:
therapeutic levels
Magnesium plasma level that causes:
ECG changes,prolonged PR, widened QRS
Magnesium plasma level that causes:
decreased tendon relfexes, respiratory depression
Magnesium plasma level that causes:
respiratory arrest, ECG changes (SA/AV conduction)
Magnesium plasma level that causes:
cardiac arrest
Hemabate drug class and MOA:
Synthetic analogue of prostaglandin F2
Stimulates uterine contraction,
Increases myometrial calcium,
Stimulates smooth muscle of GI tract to cause diarrhea
Methergine C/I:
- severe HTN (alpha stimulation of drug further increases BP)
- pregnancy-induced hypertension (PIH)
- cardiac disease
Pitocin uses:
induction of labor; control uterine bleeding postpartum and after suction D&C
Methergine MOA:
increases motor activity of uterus by acting directly on smooth muscle of the uterus to increase tone, rate, and amplitude of contraction
causes arterial vasoconstriction by ALPHA STIMULATION and inhibition of endothelial derived relaxation factor release
Methergine drug class:
Semisynthetic ergot alkaloid
Misoprostol (___)
___ (Cytotec)
Pitocin C/Is:
fetal distress, unfavorable fetal positions, previous uterine rupture
Misoprostol drug class:
Synthetic prostaglandin E1
Magnesium Sulfate (MgSO4) uses:
Used to prevent eclamptic seizures (decreases incidence of seizure by 50 %);
also to stop premature labor (tocolytic effect)
Hemabate s/e:
- Temperature –> possibly d/t effect on hypothalamic thermoregulation (can increase 2 degrees)
- Airway constriction and wheezing,
- Heart: Increased CO, BP, and PVR –> d/t constriction of vascular smooth muscle
- Diarrhea –> d/t stimulation of smooth muscle in GI tract
Pitocin s/e:
flushing, brady/tachycardia, hyper/hypotension (especially when given rapidly)
Misoprostol uses:
Indicated for uterine atony, abortions, cervical ripening, peptic ulcer disease
Magnesium Sulfate MOA:
Inhibition of acetylcholine release at NMJ
Pitocin MOA:
- Indirectly increases intracellular calcium
- directly stimulates the oxytocin receptor on the myometrium
- some antidiuretic properties
