Patient harm
Symptoms of oxytocin overdose may present where oxytocin is inadvertently given to a woman without clinical need (product mis-selection), or at a higher infusion rate than indicated. Contractions can become too frequent or last too long (uterine hyperstimulation). This can increase the risk of placental abruption and reduce the flow of blood and oxygen to the baby, causing serious harm to both mother and baby. Amniotic fluid embolism has been reported with oxytocin overdose.
Treatment with oxytocin in the management of post partum haemorrhage (PPH) is considered time critical. Any delay may worsen clinical outcome.
Clinical use
Oxytocin infusions are routinely used in the labour setting. They may be used:
• antepartum for stimulation of labour
• during labour for enhancement of labour
• postpartum during caesarean section, but following delivery of the infant and
• for prevention and treatment of postpartum uterine atony and haemorrhage
Product formulation
No licensed ready-to-administer products are currently available in the UK. Unlicensed products may be available from local pharmacy services or commercial manufacturers. Alternatively, oxytocin infusions are made up at the point of care in either a syringe or an intravenous (IV) bag.
Administration
Oxytocin may be administered by the intravenous route either as a slow bolus or an infusion.
The rate of infusion varies according to clinical use and response. Lower doses and rates of infusion are used when enhancing contractions during labour and higher doses and infusion rates are used postpartum.
Hyponatraemia
Prolonged intravenous administration of oxytocin at high doses with large volumes of fluid may cause water intoxication with hyponatraemia. The BNF includes recommendations to avoid potential harm by using electrolyte-containing diluent (i.e. not glucose), increasing oxytocin concentrations, restricting fluid intake by mouth and monitoring fluid and electrolytes.
Key risks
Product mis-selection
Harms have been reported due to practices where oxytocin infusions are prepared in advance of clinical need, in an effort to prevent delays in time critical administration. Inadvertent mis-selection of these pre-prepared oxytocin infusions when maintenance fluids were intended has caused harm.
Intravenous fluids are given regularly to women in labour and are often administered by gravity or without a volumetric pump. Any mis-selection may result in an oxytocin infusion running freely or at a significantly increased rate.
Preparation
National Patient Safety alert directives state that organisations should review and update local procedures to ensure that oxytocin infusions, for any indication, are not pre-prepared at ward level in any clinical area (including delivery suites and theatres).
Preparation in an IV bag may exacerbate the risk of mis-selection with standard intravenous fluids without additives. Preparation and administration of oxytocin via a syringe and syringe driver may support product differentiation from IV fluids. Risks of mis-selection with other medication in syringes may still be present.
Medusa can be used to identify suitable diluents and concentrations for clinical use.
Rate setting
Harms have occurred when setting and/or changing infusion rates. Examples of harm include where the oxytocin antenatal regimen is used postnatally (and vice versa) or an oxytocin infusion has been set up at a rate intended for maintenance fluids.
Practice variation
Variations in clinical reference sources, local formularies and clinical guidelines/protocols has resulted in varied practice within maternity settings across the NHS. Maternity units may not have standardised protocols and, may use different regimens within the same unit depending on obstetrician instruction.
Variation of practice may exacerbate the risk of inadvertent errors from staff unfamiliar with local standards.
Failure to comply with organisational preparation and administration checking requirements has been associated with harms.
Timely access
Barriers to timely access of the oxytocin, the consumables required for preparation and administration, or a lack of awareness of the time critical nature of oxytocin, may result in delayed therapy.
Storage
Oxytocin may be stored in locked refrigerators to comply with manufacturer’s and safe and secure storage recommendations, which may delay timely access.
The SPS Refrigerated medicines stability tool provides guidance on the off-label use of the product where the recommended storage has not been maintained.
PPH kits/trolleys
PPH kits/trolleys support timely access to equipment and medication.
Transfer of care
Known harms have occurred due to miscommunication (inadequate or missing handovers) and when reconnecting oxytocin in theatres following transfer.
Monitoring
Inadequate maternal and foetal monitoring may delay the detection of any error and increase the risk of harm. Monitoring the frequency, strength, and duration of contractions as well as the foetal heart rate continuously during therapy supports early detection.
Mitigations
When putting any mitigation strategies into practice there are considerations which may be locally unique and will require local assessment of the impact.
Standardisation of practice should not remove the need for individualised patient care.
Standardisation of practice
Ensure local policies, procedures and clinical guidelines are in place to standardise practice where possible, such as:
• ensuring oxytocin infusions are not pre-prepared in any clinical area (including delivery suites and theatres)
• utilising strategies to differentiate oxytocin from IV maintenance fluid bags and other medications.
• ensuring the infusion, including the administration line, is labelled appropriately to ensure product identification
• ensuring the roles and responsibilities of staff groups providing care in the labour setting, including theatres, are clearly defined in terms of prescribing, preparation, administration and disposal of oxytocin infusions. This should include any checks required as part of preparation and administration.
• using volumetric pumps (where available) for the administration of maintenance fluids when used concurrently with an oxytocin infusion
• ensuring clear documentation and communication of clinically appropriate monitoring, to support the early recognition of toxicity
• reviewing the diluent and oxytocin concentration used, with an aim to reduce fluid volume and minimise the risk of oxytocin associated hyponatremia.
• working with external maternal services to promote consistency in practice across the system
Timely access
Review storage and stockholding to ensure timely access to oxytocin and any consumables required for timely administration.
Consideration should be given to strategies such as:
• segregation of oxytocin within the medication fridge or a designated fridge
• risk assessed exceptions from fridge locking requirements
• storage in fridges with keypad/electronic access rather than a traditional key access
• storage out of the fridge with a reduced expiry clearly documented on product
Any decision to adopt these strategies should be risk assessed locally and detailed in the organisation’s medicines management policy.
Ensure all clinical staff working within the clinical area are aware of storage locations.
Ready to administer preparations
Review the feasibility of using ready-to-administer pre-filled syringes where appropriate.
Safety software
Prudent use of electronic safety functions, such as infusion rate limits in infusion software may limit potential harm from infusion rate errors.
Awareness and knowledge
Ensure healthcare professionals responsible for the prescribing, supply preparation, administration and monitoring of oxytocin infusions are aware of the associated key risks and have the adequate knowledge and skills required to undertake the task safely. Local training and competency requirements should meet standards outlined in any injectable medication administration policy.
Clinical alternatives
Consideration of the use of alternative products, where appropriate, may provide additional mitigation opportunities.
The NICE clinical guideline Intrapartum care advises on a number of alternative therapeutic agents to oxytocin infusion for the second-line treatment for postpartum haemorrhage.
Acknowledgments
Information on prevalent risks associated with using oxytocin infusions during and after labour was provided by the Patient Safety Team at NHS England.