Clinically Speaking

Single-Switch Driving

A Realistic Option to Consider

As therapists and providers, we have all had some very challenging and difficult clients throughout our careers. Some of our clients’ seating needs are so intricate that trying to provide them with adequate stability can take significant time and equipment. Since these clients’ seating needs are so complex, it is very easy to lose sight of the fact that we may be able to provide independent mobility to these individuals through the use of alternative controls.

When a very complex child or adult comes to us for an evaluation, the goal is to always provide them with the best opportunity for independence. In order to provide the best service we can, we need to think of every option available that may improve the client’s level of independence.

The Possibilities of a Single Switch

A few years ago, I met a little boy who was 3 years old when I was part of an assistive technology team that was evaluating him for an augmentative communication device. We found him to be very intelligent and to have a strong desire to communicate and participate in activities as independently as possible. Upon evaluation, we found that his active controlled movements were significantly impacted by his cerebral palsy. However, we did find he was able to utilize his right hip flexion consistently with a switch mounted over his right knee to control the scanning feature of a communication device.

During the trial period for a communication device, we found he was very creative and adapted quickly to the device. At this time, we had a discussion with him and his family about the possibility of using this type of switch control to move from his manual chair to a power chair for greater independence. His family said they had no idea it was a possibility for him to drive a power chair with his impaired manual dexterity. I told his family as long as he had a good access point to control a switch, then greater independence was a strong possibility. We moved forward with the process.

The power mobility evaluation was a long process requiring multiple evaluation appointments. We evaluated him for a seating system on the first appointment and then we evaluated for different alternative controls and his driving skills during the following appointments. Although we knew that single switch would probably be the best access method for driving, we wanted to be sure that all other alternative controls that might provide more direct control of the power wheelchair were ruled out first. We found his best control for driving a power wheelchair was consistent with what we had found for communication.

We decided to start him off with a four-way scanning configuration. He had rapid success with this configuration, so we moved forward to an eight-way scanning configuration. He picked up driving with single-switch scanning very quickly. He has been driving now for more than two years with single-switch scanning and has had the opportunity to try other access methods as he develops further control over his lower extremities. He continues to find that driving with an eight-way scanning system for control of his power wheelchair is the most successful for him.

Requirements for Single-Switch Driving

Single-switch scanning evaluations can be very daunting and time consuming, but the reward is incredible when we can deliver the highest level of independence to our client. It’s helpful to understand the skills a client needs to drive with single-switch scanning.

  • The client must have the vision to see the display. The devices available provide two options, either bright LED lights that move through a rotation of scanning sequences, or a brightly colored arrow on a power wheelchair display. Either option requires that the display that has the arrow or lights must be located in a spot easily seen by the user, but out of their visual field enough that it does not interfere with their vision for driving the power wheelchair.
  • The client must have the ability to attend to the scanning screen. The client must be able to watch the screen provided in all environments and visually track the scanning light or arrow of the device until it reaches the direction they want to move.
  • The client must have at least one consistent movement. This allows one-switch access to occur.
  • The client must be able to hit the switch at the appropriate time in order to choose the direction they want the power wheelchair to move. This requires timing that is not easily achieved by all clients. If their timing is off, then switch driving can be a very frustrating process. However, don’t rule out this type of driving too quickly. Give your client a chance to learn how to use the device. This at times can take many days of a trial period or, sometimes, even months to develop the ability to drive a power wheelchair.
  • They must be able to hold the switch down for as long as they desire the power wheelchair to move in the chosen direction. They must also be able to release the switch in a safe amount of time, should they get into a dangerous situation.
  • Consider what would benefit your client most, fourway or eight-way single-switch scanning. Four-way scanning offers four directions of movement for the user: forward, left, mode, reverse and right. Eight-way scanning offers more choices of direction: forward, veer forward/left, left turn, veer reverse left, mode, reverse, veer reverse right, right turn, and veer forward/right. Some clients find eight-way scanning more efficient once they can increase the speed at which the scanner moves around the scanning pattern.

Some programming options can accelerate the learning process. Turn the scan rate to a slow speed to decrease frustration. Then, as the client seems to get the hang of driving, turn the scan speed up to allow access to the different directions at a faster speed. Be sure to adjust the driving parameters such as turning speed, acceleration, deceleration and other driving parameters to ensure the wheelchair drives at an appropriate speed for your client. Try different switches to ensure you have the best switch match for the individual. Utilize light-touch switches if holding down the switch is difficult, or utilize a switch with a heavier spring in it for the client who is tough on their equipment.

Get Creative!

Remember, a switch can truly be mounted anywhere. We need to remain creative with options when looking at mounting any switch. The mounting location will probably be as unique as the individual we are working with.

We always need to remember, we owe our clients the greatest level of independence they can achieve. If it is an access method that seems labor intensive to us, we still need to allow the client to determine if it is too labor intensive for them or if the independence that the access method provides outweighs the time factor for them. Given the chance, they may just surprise you with the level of independence they can achieve.

This article originally appeared in the Pediatric Handbook August 2010 issue of Mobility Management.

About the Author

Jay Doherty, OTR, ATP, is the clinical education manager for Pride Mobility Products Corp., Exeter, Pa. Jay can be reached via e-mail at jdoherty@pridemobility.com or by calling (800) 800-8586.

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