40 Questions
What is the primary indication for administering tocolytics?
preterm labor
What is the effect of magnesium on uterine muscle?
relaxation
What is the mechanism of action of oxytocin on uterine muscle?
stimulates calcium channels, causing contraction
What is the primary indication for administering uterotonics?
postpartum hemorrhage
What is the effect of beta 2 agonists on uterine muscle?
relaxation
What is the mechanism of action of alpha 1 agonists on uterine muscle?
stimulates calcium channels, causing contraction
What is the half-life of oxytocin?
15 minutes
What is the onset of action of oxytocin?
1-2 minutes
What is the suggested dosage of oxytocin for women at low risk of postpartum hemorrhage during elective cesarean section?
20-40 IU in one liter of isotonic solution over four hours
What is the recommended dosage of oxytocin by slow intravenous injection after delivery according to the British National Formulary?
5IU oxytocin
What is the effect of continuous exposure of human myometrium cells to oxytocin?
It leads to a significant loss in their capacity to respond to oxytocin
What is the ED90 of oxytocin for women who have labored compared to non-laboring women at term?
9x higher
What is the recommended dosage of oxytocin for prevention of post-partum hemorrhage in the US?
10-40 IU/L
What is the 'Rule of Threes' in oxytocin administration?
3 units of Pit in 3 mL over 3 minutes
What is the effect of active labor on oxytocin receptor concentrations?
They are reduced
What is the suggested dosage of oxytocin for laboring patients requiring cesarean section?
Slow 3IU bolus followed by an infusion of 510U
What is a significant concern when combining methergine with other vasopressor agents?
Severe hypertension
What is the primary mechanism by which prostaglandins cause uterine contraction?
Increase in calcium concentrations
Which of the following is a contraindication for the use of methergine?
All of the above
What is a potential side effect of Hemabate?
Bronchospasm
What is the dose of Hemabate used for PPH?
250 mcg IM or intramyometrially
Which of the following is a use of misoprostol?
All of the above
What is a potential effect of PGE2 on the cardiovascular system?
Increased SVR and PVR
What is a potential respiratory complication of PGE2?
Increased intrapulmonary shunting
What is the effect of Nifedipine on the uterus?
Greater effect on uterus compared to other Calcium Channel Blockers
What is the effect of Beta-mimetics on uterine muscle?
Relaxation of smooth muscle
What is the mechanism of action of Ritodrine and Terbutaline?
Selective Beta 2 agonist producing increases in cAMP
What is the effect of Calcium Channel Blockers on the fetus?
Decreased variability
What is the combination of inhaled anesthetics and Calcium Channel Blockers associated with?
Uterine atony
What is the cause of uterine hypertonicity in the postpartum period?
Unopposed oxytocin induced tetany as epinephrine levels decrease after labor
How do Beta agonists compare to magnesium for tocolysis?
Beta agonists are superior to magnesium for tocolysis
What is the formula for uterine perfusion?
Uterine arterial pressure - Uterine venous pressure/ uterine vascular resistance
What is the primary mechanism of action of Ephedrine in terms of norepinephrine?
Inhibits norepinephrine reuptake
What is the primary indication for using Phenylephrine?
Prophylactic treatment before spinal or cesarean section
What is the primary effect of Hydralazine on the cardiovascular system?
Dilates arterioles
What is the ratio of alpha to beta receptor activity for Labetalol?
1:3
What is the primary mechanism of action of Tranexamic Acid?
Reversibly inhibits plasminogen to plasmin conversion
What is the primary indication for using Ephedrine in obstetric anesthesia?
Treatment of hypotension following neuraxial placement
What is the duration of effect of Hydralazine when administered intravenously?
2-3 hours
What is the primary benefit of using Tranexamic Acid in obstetric hemorrhage?
Reduced mortality from bleeding within three hours of delivery
This quiz covers the management of postpartum hemorrhage, uterine receptors, and their role in labor. It includes questions on oxytocin, prostaglandins, and alpha and beta receptors, as well as their effects on uterine muscle contraction and relaxation.
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