HSIB: The use of an appropriate flush fluid with arterial lines (11 August 2022)

Summary

This Healthcare Safety Investigation Branch (HSIB) investigation aims to help improve patient safety in relation to the use of a flush fluid and blood sampling from an arterial line in people who are critically ill in hospital. As its ‘reference case’, the investigation uses the experience of Keith, a 66 year old man who during a stay in a clinical care unit had blood samples taken from an arterial line which were contaminated with the flush fluid containing glucose. As a result he received incorrect treatment which led to his blood glucose levels being reduced to below the recommended limit.

Content

Arterial lines are routinely fitted for severely ill patients in critical care and are flushed with a solution to maintain patency, and ensure that blood does not clot in the line. Saline is recommended as the flush solution for arterial lines.

There is a known patient safety risk in connection with this where glucose solutions being inadvertently and incorrectly used to flush arterial lines. This has led to inaccuracies in blood glucose measurements, which resulted in unnecessary administration of insulin and subsequent cases of hypoglycaemia, some of which have been fatal.

Findings

The key findings from the investigation include:

• The physical layout and design of the clinical and storage areas will influence how reliably staff are able to select and collect similar-looking equipment and medication.
• The labelling of bags of fluids, similar looking medications and manufacturers’ packaging reduce the reliability of selecting the correct flush fluid in the context of a critical care unit with time pressures and high workloads.
• The procurement and design of arterial transducer line equipment, the pressure infusion bags and transducer, do not assist in the identification of the incorrect flush fluid or prevent contamination from the flush fluid of a blood sample taken from the arterial line. Alternative equipment, for example transparent pressure infusion bags and closed arterial transducer lines, are currently available to the NHS. These may reduce the risk but are not routinely in use.
• Challenges in the provision of a consistent suitable workforce and high workloads have a detrimental effect on the safety controls currently relied upon to avoid or identify the risk of using the wrong flush fluid. Safety checks and training lack resilience to organisational pressures regularly experienced within critical care units.
• There can be a delay in identifying the contamination with glucose of an arterial line blood sample due to a normalisation and acceptance that critically ill patients may have altered blood glucose levels and require insulin treatment, and a perceived low risk associated with the use of a flush fluid.
• The design of systems to record and monitor information relevant to the arterial transducer line system and blood glucose levels do not easily alert staff to the potential use of the wrong flush fluid.
• Recommendations issued over the last 14 years by national safety bodies and professional healthcare organisations to address the safety of blood sampling associated with arterial lines have not been effectively implemented.

Safety recommendations

The report makes the following safety recommendations:

• HSIB recommends that the Medicines and Healthcare products Regulatory Agency [Head of Metabolic Disorders and Renal Systems] engages with other national regulators and relevant stakeholders to develop design guidance on labelling and packaging specific to fluids to reduce selection errors.
• HSIB recommends that the Medicines and Healthcare products Regulatory Agency [Head of Metabolic Disorders and Renal Systems] reviews and acts on the available evidence to regulate for the use of pressure infusion bags that allow fluid labels to be read when inflated.
• HSIB recommends that the Medicines and Healthcare products Regulatory Agency [Head of Metabolic Disorders and Renal Systems] communicates to all relevant stakeholders and acts on the available evidence concerning the management of the risks associated with arterial transducer line sets.
• HSIB recommends that the Department of Health and Social Care [Director of Medical Technology], once post-market surveillance data is available, involves relevant stakeholders including the Association of Anaesthetists’ review and determine appropriate actions that could be taken to further mitigate the risk of blood sample contamination by the flush fluid when using arterial transducer line systems.
• HSIB recommends that the Association of Anaesthetists [President] works with relevant professional organisations to revise existing national guidance to manage the risks of contamination by the flush fluid when using an arterial line to take a blood sample.
• HSIB recommends that the Care Quality Commission [Chief Executive] reviews the recommendations from the Association of Anaesthetists on how to manage the risks of contamination by the flush fluid when using an arterial transducer line and determines any appropriate actions for the oversight of governance and assurance arrangements within NHS providers following.