When medical alarm standards fail patients and health professionals

A look at a lesser-known but important issue facing health providers and patient well-being: auditory masking

When medical alarm standards fail patients and health professionals
Credit: Thinkstock

Healthcare facilities are heavily regulated environments. From electronic health records to how fire doors in a hospital need to be installed, many different organizations and government agencies regulate the healthcare industry.

Medical alarms are one aspect of healthcare that is heavily standardized. The IV pump will “ding” if a tube becomes kinked. And because of movies with melodramatic scenes in the hospital, most people are aware of the heartbeat in the background beeping over the actors’ voices.

What patients, healthcare providers and family members may not realize is all alarms are required to meet an international standard. The international standard for medical electrical equipment (IEC 60601-1-8) from the International Standards Organization (ISO) specifies performance and alarm categories and sound specifications. All manufacturers design and build to the standard for their individual devices. The standard was created to help make the alarms discernible from other sounds in the hospital, but the device manufacturer will not know which alarm is most important, so a healthcare professional needs to be able to hear all of the alarms.

The problem of auditory masking

One type of challenge that hospitals and health professionals could face is an event called auditory masking. While the term sounds complex, it means people cannot hear one of the sounds or alarms due to the presence of a second sound. For example, if two alarms are identical and sound at the same time, you may hear both sounds. But due to the nature of acoustics, even if the alarms are not identical, you still might not discern the second alarm.

So, why are health professionals found to be at fault when masking occurs?

If a health professional misses an alarm, most devices record that an alarm was activated. During a root cause analysis, it’s easy for manufacturers to prove that their devices worked when the alarm went off.

However, it’s difficult to demonstrate or even record all of the devices sounding at the same time. In these situations, it’s easy to attribute the missed alert to alarm fatigue. Alarm fatigue is “sensory overload when clinicians are exposed to an excessive number of alarms, which can result in desensitization to alarms and missed alarms,” according to the American Association of Critical-Care Nurses.

Historically, to detect auditory masking, all alarms in a room would need to be recorded with the exact same method at the point in time the missed alarm would occur using acoustic recording equipment, which most hospitals do not have.

However, a new algorithm has been developed that would allow hospitals, health professionals and manufacturers to calculate if auditory masking can occur between any two devices, or any combination of devices, using the acoustic properties of sound (Paper 1). What the algorithm reveals is that even different alarms that meet the IEC 60601-1-8 standard could be imperceptible to healthcare professionals.

Another paper uses the same algorithm but applies it to a telemetry device, which monitors if a patient’s heart rate changes or stops. The alarms are set for different levels of criticality. This test demonstrated that even within a single device, alarm masking can occur (Paper 2). The unique aspect of the algorithm is that all the different permutations of when individual alarms start, whether simultaneously or a few milliseconds apart, are able to be tested, and researchers can verify whether specific alarms can and will mask.

I am part of a team that was awarded a research grant to work with the IEC 60601-1-8 standard developers, using the algorithm to improve the standard and decrease the likelihood of masking in future medical devices. In the meantime, health professionals and hospitals continue to increase the number and breadth of medical devices to treat patients. However, we now have the ability to test if health professionals should have been able to hear a specific alarm.

With alarms in the hospital, intensive care unit and operating room, our system is still setting up our health professional to fail. We can inform the health professional they were not at fault for missing the alarm and support the provider when the missed alarm resulted in the death of a patient.

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