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BED EGRESS MONITOR MAY REDUCE THE INCIDENCE OF FALLS

David Lokhorst1, Terry Rachwalski1, Mae Meller2 and Cari Wells1 1Tactex Controls Inc, Victoria, British Columbia, Canada

2Central Park Lodges, James Bay Lodge, Victoria, British Columbia, Canada

INTRODUCTION

The care aide can then assist the resident. Unfortunately, the majority of these monitors are plagued by a high number of false alarms that are annoying to care staff. The result is that bed exit alarms are often ignored or the equipment disabled by staff. This may increase the likelihood of a resident falling, and wastes money.

Currently, we are developing a monitor, called the Tactex Bed Occupant Sensor (BOS), that can detect bed exit while maintaining a low false alarm rate. The monitor is used under the bed mattress and is made of Kinotex, a pressure-sensitive foam material that incorporates an array of individual pressure sensors.

Kinotex is a fiber-optic based SmartFabric™ that acts like human skin. This material knows where it is being touched (x- and y- coordinates) and how hard (z-coordinate).

In an assisted living or nursing home environment, most falls occur at night when a resident is getting out of bed (Tideiksaar, 1998). To help prevent these falls, several companies have created bed-exit monitors. The purpose of these monitors is to alert care staff that a resident at risk for falling is getting out of bed.

PURPOSE & EXPERIMENTAL OVERVIEW

PURPOSE

This pilot study was used to test the effectiveness of 2 different bed-exit monitors, the Tactex BOS, and a commercially available monitor system that has an optional edge-of-the-bed detector (activates an alarm when the resident moves to the edge of the bed). The purpose of this pilot study was to assess the abilities of the 2 monitors to:

• Correctly reject situations where false alarms typically occur• Correctly detect bed exit

EXPERIMENTAL OVERVIEW

The effectiveness of the Tactex BOS was compared to that of the commercial monitor using a 4 bed behavior (lying on back, knees up; lying in fetal position; rolling to edge of bed; getting out of bed) X 3 bed monitor (Tactex BOS; commercial monitor – edge detection off; commercial monitor – edge detection on) protocol. The commercial monitor controller required the selection of a time delay between bed exit detection and the exit alarm sounding. The delay was set at the lowest value, 1second.

PROCEDURES

APPARATUS

Test beds were set-up with both bed-exit monitors. The Tactex BOS was placed under the mattress, while the commercial monitor was placed on top of the mattress. The Kinotex monitor was placed so that the top edge of the monitor was flush with the articulation to raise the head of the bed. The commercial was affixed as directed, on top of the mattress just below the articulation caused by raising the head of the bed.

PARTICIPANTS

The average age of participants was 67 years (sd=13 years). The participant pool was counter balanced for gender.

Placement of the commercial bed sensor and the Tactex BOS.

PROTOCOL

Participants were asked to perform 4 behaviors incorporating postures that are typical during sleeping and bed occupancy. The first 3 postures were used to test the products’ ability to correctly reject situations in which false alarms typically occur. The 4th behavior was used to test each monitor’s ability to correctly alarm during a bed exit.

 The postures and associated alarm types (false alarm or true bed exit) were:• The participant lying on their back with their knees bent, soles flat on the mattress

(false alarm)• The participant rolled onto their side with their knees bent, into the fetal position (false

alarm)• The participant straightened their legs, and rolled to the edge of the bed (false alarm)• The participant sat up, and exited the bed (bed exit alarm)

After each posture was achieved by the participant, experimenters recorded any false alarms by either product, or, in the case of bed exit, an exit alarm. The postures were tested in serial order.

 The false alarm rate for each condition was the ratio of false alarms to total trials (see Fig. 1).

The bed exit delay was calculated as the amount of time between the buttocks coming off the bed mattress and the alarm ringing.

RESULTS

False alarm rate in different sleeping positions

0%20%40%60%80%

100%120%

Knees up Fetalposition

Edge ofbed

Sleeping Position

Fa

lse

Ala

rm R

ate

(%

)

Tactex BOS

commercial monitor --edge detection on

commercial monitor --edge detection off

Figure 1: Monitor false alarm rates in different sleeping positions

Both products had a zero miss rate for bed exit, however the commercial monitor’s alarm rang after the Kinotex alarm in the edge-detection-off condition (+2.5s). Both alarms sounded at the same time in the edge-detection-on condition.

The commercial monitor was also tested in the no edge detection, 5s delay configuration. Results were similar for those of the 1s delay configuration, however lag of the commercial bed exit alarm was considerably longer.

CONCLUSION

Analyses of pilot data indicate that:

• The Tactex BOS produced fewer false alarms during the first 3 bed behaviors (no false alarms)

• The Tactex BOS detected bed exit at the same time or sooner than the other product • The commercial bed monitor detected bed-exit, however it produced false alarms during

the other bed behaviours

Based on the results of the pilot study, both bed occupant sensors will be tested in a long-term, ecological study. 

BOS technology is of interest to Health Care Practitioners, Administrators and Risk Managers, because it accurately notifies care staff of an occupant’s intent to get out of bed, and thus could be an important part of a fall prevention program. The location of the Kinotex® pad under mattress is an advantage over other products, because it means the pad is less visible, and so is less likely to upset or be tampered with by Alzheimer’s or combative residents.

Acknowledgements: References: Tideiksaar, R. (1998). Falls in older persons, prevention and management. 2nd ed.

Baltimore: Health Professions Press.