OXYTOCIN

It is an octapeptide synthesized in

hypothalamus and stored in pituitory.

Trade name:

Pitocin, Syntocinon(1 amp= 1 ml= 5 IU)

Action

 Main action is on uterine myometrium It promotes uterine muscle contraction The action is greater on pregnant uterus

as it has increased number of oxytocin receptors

Contraction of myoepithelial cells in breast cause expression of breast milk

ADH (Anti Diuretic Hormone) like effect in large doses, causes water intoxication

Indications :- TherapeuticPREGNANCY

• Second trimester abortion

• Induction of labour

• To facilitate cervical ripening for effective induction

LABOUR

• Augmentation of labour

• Active management of third stage of labour – given after separation of placenta for promoting uterine contraction and stoppage of bleeding

PUERPERIUM

• Control of post partum haemorrhage.

Diagnostic

Oxytocin challenge test (Contraction stress test)

Oxytocin sensitivity test

Routes of Administration:

IM IV BUCCAL TABLETS NASAL SPRAY

Method of administration:  Induction of labour : For induction, 2.5 -5 units of oxytocin is

added to 500ml of RL. The drip is started at a rate of 8 drops/mins and increased every 20 mts till the contractions are effective (contractions sustained for about 45 seconds and 3 contractions in 10 mts) and thereafter that drop rate is maintained. During this period continuous monitoring of fetal heart rate and contractions are done.

(4mU- 16 mU) 1 unit= 1000 mU

Control of postpartum uterine bleeding:

10 – 20 units of oxytocin is added to 500ml IVF and run at a rate to control uterine atony or 10 units oxytocin can be given IM after delivery of placenta.

For inevitable or incomplete abortion:

10 units of OCT is added to 500ml of IVF and infused at a rate of 20- 40 mU/ mt.

Contraindications:

When vaginal delivery is not possible as in cephalopelvic disproportion, malpresenatation and malposition, severe degree of placentas previa, cord prolapsed

Previous caesarean section or hysterotomy

Incoordinate uterine contraction Grand multipara Contracted pelvis Fetal distress and emergencies where

surgical intervention is  beneficial. Hypovolemic state

Side effects:

Maternal Hyperstimulation of uterus Uterine rupture Hypotension – due to vasodilation Water intoxication – when high dose

is given with large quantities of fluids – manifested as hyponatremia, convulsions and coma

Anti diuresis

Fetal

Fetal distress Fetal hypoxia

OXYTOCIN CHALLENGE TEST (Contraction Stress Test)

To assess the fetal well being during pregnancy

Indications : IUGR Post maturity Hypertensive disorders of pregnancy Diabetes

Contraindications

Compromised fetus Previous history of CS Complications likely to produce

preterm labour APH

Procedure

The oxytocin infusion is started at an initial rate of 1mU/mt which is stepped up in every 20 mts until effective contractions are established. The alterations in FHR is recorded by electronic monitoring.

Interpretation

Positive : Persistant late deceleration of FHR

Negative : No late deceleration or significant variable decelaration

Suspicious : Inconsistent but definite decelerations do not persist with most uterine contractions.

Unsatisfactory : Poor quality of recording or adequate uterine contractions not achieved.

A negative test is associated with good fetal outcome.

Where as a positive CST is associated with increased incidence of IUD, fetal distress in labour and low Apgar score

OXYTOCIN SENSITIVITY TEST This is a useful test which helps in assessing

the irritability of the uterus. Increasing uterus irritability results in labour.

Oxytocin at 0.01 unit per ml is prepared in a 10 ml syringe, and the injection administered at the end of a spontaneous contraction. The 0.01 unit is injected intravenously at minute intervals until a contraction occurs. The total dose given to this point is called the oxytocin sensitivity. If the contractions fails to start even after 4 injections, the uterus is unlikely to be responsive to induction

NURSES RESPONSIBILITY

Obtain baseline vital signs, FHR and uterine contractions. Review laboratory tests, pelvic

adequacy and maternal and fetal conditions before OCT administration.

Use an infusion pump for accurate control of infusion rate.

Monitor maternal BP, pulse and respirations and FHR every 15 mts.

Monitor each contraction its duration, frequency and intensity as well as the status of uterus in between contractions.

Maintain I/O chart and watch for signs of fluid overload.

Record all data on a flow sheet. Have magnesium sulphate available

which may be used for oxytocin induced uterine tetany.

Discontinue the infusion if : Intrauterine pressure exceeds 75 mm

of Hg. Contractions lasting over 60 seconds Contractions occurring more

frequently than every 2 mts Fetal distress

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