Risks to medication delivery using ambulatory infusion pumps: design and usability in inpatient settings

This investigation aims to improve patient safety by supporting healthcare staff in the safe use of ambulatory (portable) infusion pumps.

Ambulatory infusion pumps are small, battery powered medical devices which enable patients to continue their day-to-day activities while receiving their medication. They allow the continuous delivery of fluids, for example medication, at a programmed rate. Ambulatory infusion pumps are used to deliver medication for many healthcare needs, including administering symptom relief medication during palliative care (the management of pain and other distressing symptoms for people with an illness that cannot be cured). They are used in different care settings including hospitals, hospices and patients’ homes.

When issues with an ambulatory infusion pump arise while it is in use, the pump provides alerts to inform healthcare staff and patients. The types of alert include audible alarms, lights and warning messages. Guidance requires that staff also carry out infusion pump checks to ensure a patient’s medication is being delivered effectively.

This investigation explores this issue, focusing on the use of ambulatory infusion pumps to provide continuous symptom relief medication for patients receiving palliative care in an inpatient setting (a hospital or hospice). However, the findings may be applicable to other areas of care.

The resulting findings, safety recommendations and safety observations aim to prevent future occurrences of patients not receiving their intended medication when using ambulatory infusion pumps, and to improve care across the NHS.

The investigation used a real patient safety incident, referred to as ‘the reference event’, to examine aspects of ambulatory infusion pump use.

The reference event involved a patient named Stephen who was receiving palliative care as an inpatient on an oncology (cancer) ward at an acute hospital. His medication was delivered using an ambulatory infusion pump.

Stephen, who was 45 years old at the time of the incident, had stomach cancer and was admitted to hospital because of increased abdominal pain and an inability to swallow or keep fluids down. Stephen had previously had a small tube, called a ‘stent’, put into his food pipe (oesophagus) to help keep it open and enable him to swallow food. This stent had unexpectedly moved into his stomach, which was causing the increased abdominal pain.

Stephen had a procedure to reposition his stent and he remained on an acute hospital ward for his post-operative recovery. He was prescribed medication for pain relief and to minimise his sickness, which was delivered using an ambulatory infusion pump.

On the seventh day of his stay on the ward, there was an occlusion (blockage) in Stephen’s infusion pump, during which he did not receive his symptom relief medication. The infusion pump was fully functional, operating as designed, and providing the required visual and audible alerts, but hospital staff were not aware that Stephen’s medication was not being delivered. A subsequent coroner’s inquest report stated that ‘It is more likely than not that Stephen had intermittently silenced the alarm by pressing buttons on the syringe driver [infusion pump]’. This would have silenced the alarm without the occlusion being addressed.

Later that night Stephen was found on the ground, one floor down from the ward, outside of an open window. He was transferred to a nearby emergency department and then to a critical care ward to treat his injuries. After a period of recovery, Stephen was transferred to a specialist palliative care centre for ongoing care. After a few days he tested positive for COVID-19 after which his condition deteriorated, and Stephen died.

The reference event investigation considered many aspects of the wider healthcare system that contributed to Stephen’s care. However, this report focuses specifically on the care related to the use and monitoring of Stephen’s ambulatory infusion pump. Additional investigations were carried out by other organisations for aspects which were outside the scope of the HSSIB investigation.

An investigation was carried out to explore factors that can affect the ability of patients to reliably receive their medication via an ambulatory infusion pump. The focus was on this specific type of device as they are used widely across healthcare providers in England for patients receiving palliative care.

The investigation focused on:

• Equipment controls that enable effective delivery of medication.
• Environmental and staff factors that can influence the monitoring of medication delivery via ambulatory infusion pumps.

• Current ambulatory infusion pump alarms may not effectively notify staff of hazardous situations (situations where intervention by a healthcare professional is needed because there is potential for harm to a patient). Alarms may occur, but if staff are not alerted to them, the required interventions may not take place.
• Current national reporting systems are complicated and do not support the capture and sharing of medical device related incidents across appropriate national bodies.
• To enable the effective cross organisational sharing of incident data local incident reporting systems, which feed into the NHS England Learn from Patient Safety Events service, would need to meet the Medicines and Healthcare products Regulatory Agency (MHRA) data standards.
• The main factors that affect staff’s ability to hear an alarm and intervene in a hazardous situation are the infrastructure and working environment in which infusion pumps are used.
• When staff cannot hear or see an alarm, outside of the 4 hourly infusion pump staff checks, they are reliant on patients or families to alert them to issues with an ambulatory infusion pump. This is not always possible when the patient is unwell.
• International standards used by manufacturers of medical devices do not fully consider the environment in which the equipment is used.
• NHS staff are not always given guidance on how to use specific medical devices in the context of their varying environments, and how this may affect patient safety.
• The inability to access the Palliative Care Formulary (a best practice guide for medication prescribers), as a free resource, may have an impact on patient safety. This can be both in the palliative care specialism and across the wider healthcare system.