WOMEN AND NEWBORN HEALTH SERVICE
King Edward Memorial Hospital
CLINICAL GUIDELINES
OBSTETRICS & MIDWIFERY
INTRAPARTUM CARE
INDUCTION OF LABOUR
OXYTOCIN INFUSION
Keywords: syntocinon infusion, oxytocin infusion, oxytocin induction, labour stimulation, hyperstimulation
See Clinical Guidelines, Restricted Area Guidelines (O&M): Induction of Labour (Intranet only) for
management prior to commencing an induction of labour.
AIM
To provide guidance on the use of an oxytocin infusion for labour, including contraindications,
dose/dilution, infusion rates, and management of possible complications.
KEY POINTS
1.
2.
These infusion guidelines are as per the ACOG review October 2010.
The maximum infusion rates are as per the RCOG guidelines.
1
ABSOLUTE CONTRAINDICATIONS
Any condition in which spontaneous labour is inadvisable
2 or more previous caesarean sections
RELATIVE CONTRAINDICATIONS
Grande multiparity (> P4) – discuss with the consultant
1 previous caesarean section – discuss with the consultant
Secondary arrest in active labour in a multiparous woman – discuss with consultant
PRIOR TO COMMENCING OXYTOCIN
Oxytocin should not be started for six hours following administration of vaginal
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prostoglandins.
For women with intact membranes an ARM should be performed prior to commencing
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induction.
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Establish fetal well-being immediately prior to commencement of oxytocin. Perform a 20-30
minute cardiotocograph (CTG) prior to commencing the induction.
Women with a previous uterine scar and / or high parity (greater than 4) should not have
oxytocin commenced without discussion with the obstetric team Consultant.
Women with a previous caesarean section scar should have discussion and consent to the
use of oxytocin. The rupture risk (approximately 1:100) should be explained and this
discussion documented in the medical notes.
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All guidelines should be read in conjunction with the Disclaimer at the beginning of this section
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DOSE
To reduce error a standard dilution should always be used.
Standard Dilution of Oxytocin
10 I.U. of oxytocin in 500mL of Hartmann’s solution.
At this dilution, a 3mL/hr infusion rate equates to
1milli-unit (mU) of oxytocin per minute.
INFUSION RATE
The dose of oxytocin should be titrated against uterine contractions. The aim is to achieve a frequency
of one contraction every two and half to three minutes, lasting 60 seconds using the minimum dose of
oxytocin possible.
Labour Stimulation with Oxytocin
Starting Dose
Incremental Increase
Dosage Interval
Increase the infusion
Increase the infusion rate by
rate at 15 minutely
4 mU per minute (12mL / hr) to a
intervals
maximum dose of
20 mU per minute (60mL / hr).
Once the maximum dose has been running for 30 minutes the Consultant or Senior
Registrar should review the woman prior to higher doses being administered. The
overall maximum dose of oxytocin should not exceed
36 mU per minute (108mL/hour)
4 mU per minute
(12mL / hr).
Once an ideal uterine contraction pattern has been achieved, titrate the dose to
maintain the pattern.
In the case of grande multipara(>Para 4) or a previous caesarean section, the regime
may be modified after discussion with the consultant
Oxytocin Infusion Conversion Chart
Time after starting
Oxytocin dose
Volume infused
(minutes)
(mU per minute)
(mL per hour)
0
4
12
15
8
24
30
12
36
45
16
48
60
20
60
75
24
72
90
28
84
105
32
96
120
36
108
Doses shaded yellow are above the licensed maximum dose and require Consultant
or Senior Registrar review prior to administration.
DURING ADMINISTRATION
Deliver the oxytocin through an infusion pump and ensure the giving set has a double or triple
lumen peripheral set (V-set) attached. Note: The V-Set acts as an anti reflux valve preventing
bolus administration of oxytocin.
Where the oxytocin infusion is to run as a sideline to a main intravenous line, it should be
connected to the main line with a V-Set.
Ensure continuous electronic fetal heart rate monitoring and monitoring of uterine contractions
throughout the induction using continuous electronic cardiotocography.
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All guidelines should be read in conjunction with the Disclaimer at the beginning of this section
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Place an intrauterine pressure catheter in women whose contractions cannot be adequately
assessed by external monitoring or manual palpation.
Monitor fluid balance.
Ensure constant midwifery support. The woman should have one-on-one midwifery care while
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have oxytocin infusion.
POTENTIAL COMPLICATIONS OF OXYTOCIN INFUSION
Complications that may potentially occur with oxytocin use include:
Uterine Hyperstimulation
4
4
Hyponatraemia .
hypotension
4
nausea and vomiting (infrequent)
5
Rarely – arrhythmias, anaphylactoid reaction
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UTERINE HYPERSTIMULATION
Uterine hyperstimulation from the use of oxytocin or prostaglandins induction of labour occurs in 1-5%
3
of women. Oxytocin has a short half life from 1-5 minutes and is easy to titrate should
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hyperstimulation occur.
Uterine hyperstimulation is defined as:
5 or more contractions in 10 minutes
3, 4
3
contractions lasting more than 90 seconds to 2 minutes.
4
contractions of normal duration occurring within 1 minute of each other.
4
Management of Hyperstimulation with FHR Decelerations or Abnormalities
3, 4
1. CEASE THE OXYTOCIN INFUSION
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2. Reposition the woman onto her left side.
3. Notify the midwifery Co-ordinator and the Medical Obstetric Team.
4. Consider tocolysis with Terbutaline 0.25mg subcutaneously if cessation of the oxytocic
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infusion fails to resolve hyperstimulation. A response from Terbutaline should occur within 510 minutes. Note: Terbutaline is contra-indicated in women with cardiac disease.
5. Prepare the woman for immediate vaginal delivery or possible Caesarean delivery if the FHR
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does not return to normal.
6. If the uterine hyperstimulation resolves, re-start the oxytocin infusion at half the rate of the last
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dose infused, and increase the rate as required.
Management of Uterine Hyperstimulation without Fetal Compromise
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Decrease the oxytocin infusion rate. If in doubt, cease the oxytocin, reassess the clinical situation
and discuss the management with the Medical Obstetric Team.
HYPONATRAEMIA
Oxytocin is similar in structure to vasopressin and in high doses may cause water retention. With the
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use of isotonic solutions it is rare. It can occur with prolonged infusions and if hyponatraemia is not
recognised can lead to seizures, coma and death. Pulmonary oedema may also occur without
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hyponatraemia.
To reduce the risk of hyponatraemia:
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Monitor and record fluid intake and output at least 2 hourly during oxytocin infusion.
Apply caution with use and careful monitoring of fluid balance for women with cardiac conditions.
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HYPOTENSION
If oxytocin is given as a bolus dose it can cause significant hypotension. Use of infusion pumps
prevents this risk. If a rapid injection is given it can cause transient hypotension, flushing and reflex
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tachycardia.
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All guidelines should be read in conjunction with the Disclaimer at the beginning of this section
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REFERENCES (STANDARDS)
1.
2.
Novartis Syntocinon ® Product Information. 2009
McGeown P. Induction of Labour and Post-term Pregnancy. In: Henderson C, MacDonald S, editors. Mayes'
Midwifery. 13th ed. London: Bailliere Tindall; 2004. p. 862-75.
3.
Thorogood C, Donaldson C. Disturbances in the rhythm of labour. In: Pairman S, Pincombe J, Thorogood C, Tracy S,
editors. Midwifery Preparation for Practice. Sydney: Churchill Livingstone; 2006. p. 679-716.
Smith JG, Merrill DC. Oxytocin for Induction of Labor. Clinical Obstetrics and Gynecology. 2006;49(3):594-608.
4.
5.
6.
7.
8.
Royal Australian College of General Practitioners, Australian Society of Clinical and Experimental Pharmacologists and
Toxicologists, Pharmaceutical Society of Australia. Australian Medicines Handbook. Adelaide; 2008.
Harman JH, Kim A. Current trends in Cervical Ripening and Labor Induction. American Family Physician.
1999;60(2):477-83.
Shiers C. Prolonged Pregnancy and Disorders of Uterine Action. In: Fraser DF, Cooper MA, editors. Myles Textbook
for Midwives. 14th ed. London: Churchill Livingstone; 2003.
Wei et al.High Dose vs Low Dose Oxytocin for labor augmentation.American Journal of O&G. 2010.
National Standards – 4 Medication Safety
Legislation – Poison’s Act 1965
Related Policies - Nil
Other related documents –KEMH Clinical Guidelines:
Obstetrics & Midwifery: Intrapartum Care;
Restricted Area Guidelines: Induction of Labour
RESPONSIBILITY
Policy Sponsor
Medical Director OGCCU
Initial Endorsement
July 2008
Last Reviewed
September 2014
Last Amended
February 2015
Review date
September 2017
Do not keep printed versions of guidelines as currency of information cannot be guaranteed.
Access the current version from the WNHS website.
2014
All guidelines should be read in conjunction with the Disclaimer at the beginning of this section
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