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Oxytocin: Nursing Pharmacology

Notes

Notes

OXYTOCIN
DRUG NAME
oxytocin (Pitocin)
CLASS
Uterine stimulant, oxytocic
*High Alert Medication*
MECHANISM OF ACTION
  • Increases intracellular calcium in uterine smooth muscle, which causes uterine muscle contraction
  • Causes contraction of the myoepithelial cells around milk-containing alveoli, resulting in milk ejection during lactation
INDICATIONS
  • Induce or augment labor
  • Control postpartum bleeding
  • Manage incomplete or inevitable abortion
ROUTE(S) OF ADMINISTRATION
  • IV
  • IM
  • NAS
SIDE EFFECTS
  • Uterine hyperstimulation 
  • Nausea, vomiting
  • Hypertension
  • Cardiac arrhythmias
  • Amniotic fluid embolism
  • Water intoxication
CONTRAINDICATIONS AND CAUTIONS
Contraindications / avoid use of oxytocin
  • Cephalopelvic disproportion
  • Fetal malpresentation
  • Umbilical cord prolapse
  • Non-reassuring fetal status
  • Active genital herpes
  • Hypertonic uterus
  • Unripe cervix
  • Grand multiparity
  • Uterine prolapse
  • Clients at risk of uterine rupture
Avoid use in clients receiving vasopressors or prostaglandins like carboprost

Boxed warning: Should be used for medical rather than elective reasons
OXYTOCIN: NURSING CONSIDERATIONS
OXYTOCIN ADMINISTRATION DURING LABOR
  • Start a primary line with 1000 mL IV fluid, e.g. LR
  • Start a second line with standardized concentration of oxytocin in IV fluid
  • Ensure the bags and tubing are labeled clearly
  • Insert oxytocin infusion into mainline IV by connect to port nearest to IV insertion site
  • ALWAYS administer oxytocin via infusion pump
  • Titrate infusion according to client and fetal response
  • Document the start time, end time, dose, and any changes made during administration
MONITORING
  • VS and I&O
  • Frequency, duration, and force of contractions; resting uterine tone
  • FHR pattern
  • Side effects; uterine hyperstimulation; e.g., tachysystole (excessively frequent uterine contractions), uterine tetany (excessively long contractions), nausea, hypertension
  • Signs / symptoms of water intoxication; e.g., headache, irritability, confusion, nausea
UTERINE HYPERSTIMULATION OR ABNORMAL (CATEGORY III) FHR
  1. Immediately stop the infusion
  2. Turn the client on their side, stay with them while you ask another nurse to notify the HCP
  3. Increase the rate of the mainline IV fluid (NOT the fluid containing oxytocin)
  4. Provide supplemental oxygen at 8–10 L/min via face mask
  5. Assess VS and FHR
  6. Document your findings, interventions, and client’s response
OXYTOCIN ADMINISTRATION DURING POSTPARTUM
  • Administer IV or IM
  • Closely monitor fundal tone, fundal height, and position; vital signs, pain, and bleeding
CLIENT EDUCATION
  • Provide client education about how oxytocin will affect their contractions
  • Report headache, dizziness, palpitations, or intense pain
Transcript

Oxytocin is a peptide hormone released by the posterior pituitary that causes uterine muscle contraction during labor. It’s also responsible for the milk let-down reflex where milk is ejected during breastfeeding.

It’s commonly used to induce labor or help strengthen uterine contractions to facilitate delivery. After delivery of the placenta, it’s used to treat uterine atony, prevent postpartum hemorrhage and to manage incomplete or inevitable spontaneous abortion.

Okay, a synthetic version of oxytocin is used clinically. To induce labor or strengthen contractions, it’s administered via IV.

After reaching the uterus, it will activate receptors on smooth muscle cells and trigger calcium ion release from the sarcoplasmic reticulum.

This increase in intracellular calcium will cause the muscle to contract harder with increased frequency and duration in order to help with the delivery.

When used postpartum, the uterine contractions will squeeze intrauterine vessels to slow or stop postpartum hemorrhage.

Now, when oxytocin is administered as a nasal spray it causes contraction of the myoepithelial cells around milk-containing alveoli in the breasts. This will squeeze the milk into the lactiferous ducts where it could be ejected during lactation.

The main adverse effects of oxytocin are related to uterine hyperstimulation, where there’s too much contraction. This could cause painful contractions, and lead to uterine rupture and hemorrhage. It could even restrict placental blood flow, resulting in abnormal fetal heart rate patterns.

Other side effects include nausea, vomiting, hypertension, cardiac arrhythmias and amniotic fluid embolism. With prolonged use, it could have an effect similar to antidiuretic hormone and increases water retention. This is particularly dangerous since it could cause water toxicity and result in coma or even death.

Oxytocin is contraindicated or used with caution when vaginal delivery could increase the risk of complications. Common contraindications include the presence of non-reassuring fetal status, in fetal prematurity where the lungs are not fully developed, cephalopelvic disproportion, cervical cancer, active genital herpes infection, unfavorable fetal position, placenta previa, vasa previa, and any other obstetric emergencies that could require surgical intervention.

It should also be avoided in those with grand multiparity, meaning they’ve given birth 5 or more times, and those with uterine prolapse, or at risk of uterine rupture, like clients with 2 or more previous cesarean births.

Finally, it should not be used if the client is receiving a vasopressor like phenylephrine, since both can increase blood pressure.

Now, nurses are responsible for safely administering oxytocin during labor, avoiding excessive stimulation to the uterus or harm to the fetus. So, before starting the infusion, be sure to review the client’s medical record to be sure there are no contraindications to administration.

Assess the cervix to ensure it is ripe, meaning that it has started to change from being firm and thick to soft and thin. Then, confirm that the fetal presentation is favorable for vaginal delivery, and that the estimated fetal gestational age is known.

In addition, assess the fetal status by determining the baseline fetal heart rate or FHR variability, and the presence of accelerations or decelerations.

Finally, teach the client about what to expect as far as contraction strength, duration, and frequency, review measures used to monitor maternal and fetal well-being, and stress the importance of promptly reporting if pain, nausea, or other unpleasant symptoms occur.

Sources
  1. "Pharmacology: A Patient-Centered Nursing Process Approach" Elsevier Health Sciences (2014)
  2. "Focus on Nursing Pharmacology" LWW (2019)
  3. "Awhonn's Perinatal Nursing"  (2020)
  4. "Mosby's 2021 Nursing Drug Reference" Mosby (2020)
  5. "Oxytocin" National Center for Biotechnology Information (2021)
  6. "Oxytocin: Its Mechanism of Action and Receptor Signalling in the Myometrium" Journal of Neuroendocrinology (2014)