CL IN ICAL ENGIN E E R ING
Ensuring safe, effective healthcare technology
Adverse events involving medical devices continue to occur. Understanding and learning from these events is crucial to protecting patients from harm. John Amoore describes how the safe and effective application of medical devices can be enhanced by analysis of care processes using holistic models.
Safe and effective is the core requirement for medical devices application in healthcare. Safe, because it should do no harm; effective, because it should add value to the care. Most applications are safe and effective, but failures do occasionally occur. The importance of using failures to learn how to prevent repetitions demands an open-minded analysis of the causes that recognises the nature of the care environment and inter-relationships between its elements, rather than assuming device malfunction or misuse.
The patient, care team, medical device, care plans and operating procedures and the clinical environment and its infrastructure constitute a care system. Each element interacts to support care. Reason1
shows,
using the Swiss Cheese model, how weaknesses in the elements and their interactions combine to cause accidents. His model shows how protections and barriers prevent failures causing adverse events. Care for patients is the aim of health systems. The Keystone model2
emphasises
this with the patient the focus. Thus figure 1 shows the patient as the system’s core, supported directly or indirectly by the other elements, with the elements interacting. Carers have a special place because of their direct interactions with the patient, and because the other elements, including the devices, are often applied to help care teams support the patient. Failures of element inter- relationships or of the elements themselves can cause adverse events.
Safe and effective application Reason’s model1
shows that adverse events
may be caused by failures of more than one element and by relationships between elements. Consider for example a patient with unstable physiology in critical care (figure 2). A vital-signs monitor records the patient’s condition, with provision for alarms
FEBRUARY 2021
to alert carers if any deterioration is detected – for example, heart rate decreasing. Detection requires alarms to be appropriate for the patient’s condition. Ideally, the monitor will have been configured by the installing clinical engineers with default alarms based on the clinical requirements of the particular department. The clinical engineers are part of “Infrastructure and Support” (figure 1); their configuration requires teamwork, communication with the care team optimising the alarm settings. At the point of care, alarms may be changed to match requirements of particular patients. The care team need to understand the monitor’s alarms and when and how to tweak to optimise for specific patients. Carers should understand technical limitations of alarms, such as an inability to always detect abnormal cardiac arrythmias. An important barrier to failures becoming adverse events is the vigilance of the care team (figure 2). Examples of elements are shown in
figure 2 which is based on Reason’s Swiss Cheese model. The critically ill patient is monitored by a physiological monitor, its alarms set appropriately to alert to any patient deterioration. Multiple barriers help prevent adverse events, but these barriers may have vulnerabilities – holes, that allow failures to strike through, leading to adverse events. Failures are possible in any element, care team, medical device, infrastructure and operating procedure and their interactions. Alarms were chosen to illustrate incident causes as they are frequently included in the ECRI Institute’s (
www.ecri.org) annual list of “Top 10 Healthy Technology Hazards”. The 2019 report3
draws attention to two alarm
failures that are amenable to prevention: ventilator alarm settings not matched to the patient’s condition; and failure to customise physiological patient monitor alarms. The advice to match alarms to the patient’s condition re-enforces the Keystone model2 placing the patient as the focus of the care
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