ppt chapter 53-1

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Chapter 53

Drugs Affecting Uterine Motility

Chapter 53

Drugs Affecting Uterine Motility


QuestionQuestion

• Which of the following hormones is responsible for uterine contractions?

– A. Progesterone

– B. Estrogen

– C. Prolactin

– D. Oxytocin


AnswerAnswer

• D. Oxytocin

• Rationale: Oxytocin is the hormone responsible for uterine contractions.


PhysiologyPhysiology

Contractions and related changes

• The induction of labor is related to oxytocin.

• The oxytocin receptors that are located in the endometrium increase during labor and reach peak levels at birth.

• Prostaglandins also have a role in preparing the uterus for labor and delivery.

• Prostaglandin E2 (PGE2) leads to sensitization of the myometrium to oxytocin.


Uterine MusclesUterine Muscles


PathophysiologyPathophysiology

• Occasionally, uterine function proceeds abnormally.

• Two main categories of obstetric situations require drug administration to initiate the onset of contractions:

– Labor that does not begin at term

– Pregnancy that is detrimental to the patient or her fetus


Oxytocics Oxytocics

• Oxytocic drugs are synthetic forms of the endogenous posterior pituitary hormone oxytocin.

• They produce uterine contractions and milk ejection for breast-feeding.

• Prototype drug: oxytocin (Pitocin)


Oxytocin: Core Drug Knowledge Oxytocin: Core Drug Knowledge

• Pharmacotherapeutics

– Given by IV drip infusion to initiate or augment (improve) labor contractions

• Pharmacokinetics

– Administered: IV. Onset: immediate. Elimination: liver, kidneys, and mammary glands.

• Pharmacodynamics

– Synthetic, exogenous oxytocin has the same effects on the body as natural, endogenous oxytocin.


Oxytocin: Core Drug Knowledge (cont.)Oxytocin: Core Drug Knowledge (cont.)

• Contraindications and precautions

– Cephalopelvic disproportion and unfavorable fetal positions

• Adverse effects

– Nausea, vomiting, uterine hypertonicity, and cardiac arrhythmias

• Drug interactions

– Sympathomimetic drugs


Oxytocin: Core Patient Variables Oxytocin: Core Patient Variables

• Health status

– Assess pelvic adequacy.

• Life span and gender

– Assess duration of pregnancy.

• Lifestyle, diet, and habits

– Consider the patient’s risk of water intoxication.

• Environment

– Assess environment where the drug will be given.


Oxytocin: Nursing Diagnoses and Outcomes Oxytocin: Nursing Diagnoses and Outcomes

• Risk for Fetal or Maternal Injury related to uterine hypertonicity secondary to oxytocin therapy

– Desired outcome: The mother and fetus will progress through labor and delivery without injury while on oxytocin therapy.

• Excess Fluid Volume related to drug-induced water intoxication and altered electrolyte levels

– Desired outcome: The patient’s fluid status will remain normal while on oxytocin therapy.


Oxytocin: Planning and InterventionsOxytocin: Planning and Interventions

• Maximizing therapeutic effects

– Assess cervical ripening using the Bishop scoring system before oxytocin therapy starts.

– Use an infusion pump for precise administration of oxytocin.

• Minimizing adverse effects

– Piggyback the diluted oxytocin solution into a primary IV line.

– The FHR monitor continuously records the patient’s uterine contraction pattern.


Oxytocin: Teaching, Assessment and EvaluationOxytocin: Teaching, Assessment and Evaluation

• Patient and family education

– Educate the patient and family about the rationale for oxytocin use.

– Explain that the patient and fetus will be monitored closely.

• Ongoing assessment and evaluation

– Throughout induction, monitor continually for evidence of adverse maternal or fetal effects.


QuestionQuestion

• Which of the following is the severe adverse effect(s) of oxytocin?

– A. Water intoxication

– B. Uterine rupture

– C. Permanent CNS damage to the fetus

– D. Both B and C

– E. All of the above


AnswerAnswer

• E. All of the above

• Rationale: Severe adverse effects include water intoxication and rupture of the uterus.

• Other adverse fetal effects are premature ventricular contractions and other arrhythmias, impaired fetal oxygenation, permanent brain or CNS damage, and death.


Tocolytics Tocolytics

• Drugs that inhibit uterine activity are classified as tocolytics.

• Preterm labor is the medical complication requiring the administration of tocolytics.

• Tocolytics are used when true labor begins after 20 weeks’ gestation and usually before completion of the 34th gestational week.

• Currently, several drugs are used for their tocolytic properties.

• Prototype drug: terbutaline (Brethine)


Terbutaline: Core Drug Knowledge Terbutaline: Core Drug Knowledge

• Pharmacotherapeutics

– Off-label to control preterm labor in pregnancies of 20 to 34 weeks

• Pharmacokinetics

– Administered: SC or oral. Onset of action is faster when given SC.

• Pharmacodynamics

– Beta-receptor agonist (stimulant) that selectively prefers the beta-2 receptors over beta-1 receptors .


Terbutaline: Core Drug Knowledge (cont.)Terbutaline: Core Drug Knowledge (cont.)

• Contraindications and precautions

– Contraindicated before the 20th week of pregnancy

• Adverse effects

– Tachycardia, hypotension, dyspnea, nervousness, transient hyperglycemia, pulmonary edema, cerebral and myocardial ischemia, nausea, and vomiting

• Drug interactions

– Other beta stimulants


Terbutaline: Core Patient Variables Terbutaline: Core Patient Variables

• Health status

– Assess for contraindications to therapy.

• Life span and gender

– Pregnancy Category B

• Environment

– Assess environment where drug will be given.


Terbutaline: Nursing Diagnoses and Outcomes Terbutaline: Nursing Diagnoses and Outcomes • Risk for Injury to the mother from adverse effects of drug

therapy

– Desired outcome: No adverse effects will occur from drug therapy.

• Risk for Injury to infant stemming from premature delivery or adverse effects from drug therapy

– Desired outcome: Drug therapy will prevent premature delivery of infant and will not cause adverse effects to the newborn.

• Excess Fluid Volume, pulmonary edema, related to potential adverse effects of drug therapy

– Desired outcome: The patient’s fluid volume will remain within normal limits.


Terbutaline: Planning and InterventionsTerbutaline: Planning and Interventions

• Maximizing therapeutic effects

– Begin drug therapy as soon as possible after preterm labor is diagnosed.

• Minimizing adverse effects

– Closely monitor the patient’s fluid status and avoid fluid overload.

– If the patient demonstrates signs of adverse effects, the dosage of terbutaline should be decreased.


Terbutaline: Teaching, Assessment, and EvaluationTerbutaline: Teaching, Assessment, and Evaluation

• Patient and family education

– Educate the patient and family about the therapeutic and adverse effects of the drug.

– Explain to the patient the rationale for lying on her left side.

• Ongoing assessment and evaluation

– Monitor the maternal heart rate, FHR, and maternal blood pressure and fluid status throughout terbutaline therapy.


QuestionQuestion

• Terbutaline inhibits contractility of uterine smooth muscle by inhibition of the alpha receptors in the uterine smooth muscle.

– A. True

– B. False


Answer Answer

• A. True

• Rationale: Terbutaline is a beta-receptor agonist (stimulant) that selectively prefers the beta-2 receptors over beta-1 receptors.

• Stimulation of these receptors inhibits contractility of uterine smooth muscle.

ppt chapter 53-1

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