Fall Detection in PERS Devices

Fall Detection in PERS Devices

Jim Lipman, GoFind Inc.

According to the National Council on Aging falls are the leading cause of fatal injury as well as the most common cause of non-fatal trauma-related hospital admission for seniors. More than one-third of seniors over the age of 65 fall each year, many more than one time, and in the U.S. a senior dies from a fall every 19 minutes

This is a serious problem that is addressed by many of the PERS (Personal Emergency Response Systems) in two ways – an SOS button that allows the person who has fallen to get help and, more recently, built in fall-detection in the devices themselves.

The Problem with “True” Fall Detection

No PERS fall detection sensor is perfect, which would be defined as always detecting a true fall and never identifying a “false” fall as a real one. An example of a false fall would be if someone wearing a wrist PERS gestured and hit a cabinet or wall with their hand (and I imagine many of us have done this). The sudden deceleration of the accelerometer in the fall detection sensor could easily be interpreted as a fall by the person wearing the PERS.

Ideally the fall detection algorithm should be designed such that a true fall would never be missed, even though sometimes a false fall may be flagged as a true fall. This is analogous to the U.S. justice system, which is designed such that the probability of an innocent person being convicted of a crime should be far less than a guilty person not being convicted of a crime they really did commit. This is why when a PERS fall detection sensor identifies what it thinks is a true fall, before summoning help it should be able to check with the PERS wearer is they really have fallen, for example, verifying the fall by asking the wearer if they are all right. 

Algorithms and Firmware are the Keys

Most wearable automatic PERS fault detection devices depend on measurements from a 3-axis accelerometer working with multiple sensors along with proprietary algorithms for detecting a true fall and minimizing flagging a false fall as a true one. However, because of the potential danger of not detecting a true fall, it’s better to have the risk of an occasional false alarm than be left without a way to get help in the event of a true fall.

Do Your Homework

The various PERS providers each have their own set of hardware and fall detecting algorithms, often proprietary, for automatic fall detection. When choosing a PERS with this capability it is a good idea to do some research on the provider to determine how good a job they do automatically detecting a fall. There are several articles written by third-party medical device evaluators that can provide advice on which PERS devices do the best job of automatic fall detection. 

Another consideration is comfort – if an elder isn’t comfortable with their medical alert device, they may not wear it all the time, which negates the fall detection feature. Also – the device must be waterproof, since many falls occur in the bathroom when the wearer is showering or bathing.

Being an educated consumer is always a good idea but is especially important when making a decision that can affect the health and quality of life of a loved one. 

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