Powerchair scripting – the functional effects of choices
Bachelor of Physiotherapy (BPhty)
Astris PME Clinical Educator
So you’ve made the decision to recommend powered mobility for your client.
This could be for a number of reasons such as reducing the stress on shoulder joints, insufficient strength, fatigue, independence, or accessing powered seating functions. Overall, there are likely several goals for wheelchair users and their families as well as the clinical considerations of their therapy team to take into account.
Power Wheelchairs can open up a world of possibilities for those who experience difficulty with mobilising and being able to reposition when seated. However, the effectiveness of the powerchair to achieve all the goals (clinicians and clients), is dependent on the choices made at the time of scripting.
Essentially it will come down to:
- Clinical Factors – Identifying the needs of the client and risks associated with not meeting each need. Then, deciding what is non-negotiable (such as pressure relief, postural control, and drive access) and what can be compromised (additional features such as standing function, multiple transport options, or all-terrain access).
- Lifestyle Factors – environment of use and transport considerations. What does their everyday look like and where do they need to go?
- Personal Choice – what is a “need to have” Vs “nice to have”? Do any of these choices compromise any of the non-negotiables?
This should all come together to provide a picture of what powered mobility needs to provide for the client. It is important to note that this will be unique to each client despite possibly having similar diagnosis and demographics to others.
The order of the below choices is still up for debate as they all influence each other. These are the broad areas for consideration, which all have an impact on the outcome for your client.
A good place to start is knowing what is required to meet the postural and pressure needs of the client. This is key to ensure you can make the decision on which type or model of power wheelchair is going to be suitable.
For this, you should consider:
- The level of postural support required. Will the use of an integrated seat (low level of support) with no power seat functions meet this need? Or is a specialised seating system with high support required to meet complex needs?
- Complex seating will need to be mounted to the power wheelchair and will likely be used with power seating functions. How will the chosen seating system mount to the powerchair?
- If there are any other seating options such as head or lateral supports, belts, harnesses, etc, that will impact on mounting.
- How the materials of the cushion interact with the suspension capabilities of the powerchair.
Keep in mind that a great seating prescription can be undone by not correctly matching to a suitably scripted powerchair.
Power Seating Functions:
Knowing which power seat functions are required is also key when prescribing seating on a power wheelchair. The options are tilt, recline, seat elevate, foot elevate, and standing, with combinations selected based on client need (determined at initial assessment). Not all power wheelchair models with powered seat function have all these features. It is vital to know if the power wheelchair selected has the functions required by the client and that they work in a way which is easily accessible.
During the initial assessment, a decision would have been made as to how the client is going to control the chair. This will include the consideration if proportional or non-proportional controls will be used and which type of each will be selected. Access options are varied across manufacturers with additional options also available. Knowing that some power bases drive better when alternative controls are used over other chairs will also help set up for success. Being clear at the start as to what you are needing to achieve and if customisation is required will guide your selection.
There is usually little choice of castor on a particular model of powerchair, therefore this should be considered when making a choice of chair model at the start. Differing options of size, width, material, and suspension in the castor arm can make a huge difference to how a chair drives, the feel of the ride, and how well it manoeuvres.
The Power Base and Drive wheel position:
All power wheelchair bases have their pros and cons, and you will also need to consider the motor capabilities of each model to make the best choice. It comes down to, “What do you need the chair to do? What goals are you trying to achieve?”. Remembering that a compromise is likely to be needed, so understanding what is most important to the client should remain front of mind.
Rear Wheel Drive is great for driving in outdoor community spaces and performs well at higher speeds. It is stable with some climbing ability and generally has good ground clearance. It also offers great control with non-proportional inputs. However, it does have the biggest footprint and users generally need to have good spatial awareness to manoeuvre the chair as the drive wheels are behind them. This could be overcome safely with some training and experience but is a good reminder that using a rear-wheel-drive power chair takes some skills and experience to learn to drive it. A rear wheel drive also has poorer traction on steep downhill slopes.
Front Wheel Drive has great climbing ability and small front castors which means the user can get close to desks. Smaller castors also means that tighter foot placement can be achieved. It does however have poorer control with non-proportional inputs, or when travelling at higher speeds. Similar to rear wheel drive, users generally need to have good spatial awareness to manoeuvre the chair with the drive wheel now out in front of them.
Mid Wheel Drive is more intuitive to drive as you are turning from where you are sitting. This also means it has the smallest turning radius, and therefore the smallest footprint of the group. It does however require the use of front and rear stabilisers and castors which can impact on transfers and front access. Awareness of this is required as they can have a tendency to get “hung” on dips such as curbs if approached on the wrong angle. Overall, a mid-wheel drive power base can suit most clients and their needs with the greatest potential of overall use. It is also the most prescribed power base set up.
Four Wheel Drive / All Terrain. These powerchairs are often larger with the compromise being reduced manoeuvrability to enable off-road capabilities. These are generally not a good choice for indoor mobility unless you have a large home, wide hallways, and hard flooring; however they are amazing for opening up the opportunities for access in the great outdoors.
Seating and power base considerations:
The use of power seat functions will also influence the seat base to power base positioning and the chair’s functioning. For example, recline and tilt will both shift the balance of the client’s weight on the power base. Therefore, knowing their drive position is incredibly important and should be accounted for when putting the whole picture together.
Along with the considerations of base is the question of suspension, how this is achieved on the base, and how it interacts with the seating. Every chair is different so check the ride quality over the surfaces the client is going to be accessing. For example, a Roho cushion might be indicated for pressure relief but can be unstable when paired with an all-terrain option such as the X8 and used on rough walking tracks.
The tyres on a powerchair form a part of the suspension package of the powerchair base. These may also determine, to some extent, the terrain the user is going to be able to access. Selection is therefore very important, and knowing which powerchairs offer which options is handy to know. A smaller, narrower solid tyre will give you amazing manoeuvrability on flat surfaces inside, but will struggle over gravel or grass outdoors. Likewise, a wider, pneumatic, low-pressure tyre is great for traction over rough surfaces and gives a softer ride but can make turns inside a struggle if the turn space is tight.
There’s also the debate over maintenance of a pneumatic tyre versus a solid or hybrid tyre. There are obvious advantages to a solid tyre but remember to consider ride feel. There is little advantage in scripting a solid tyre if this then affects the feel of the ride to the point the client can’t use the chair.
Now that you’ve made all the choices on the script for a powerchair and seating it should all just come together, right?
In fact, this is where the skills of an experienced therapist and/or an AT specialist really come to the fore.
For example, placement of the seating base on the power base in relation to the drive wheels has a big impact on the balance of the chair. Too much weight over the castors will cause it to drive and turn heavily. There is also a concern with the chair becoming “tippy” towards the front when encountering curbs and slopes. Placed too far back, and there won’t be enough weight over the front castors so castor flutter can become an issue.
Overall, ensuring an optimal set up for the user at the start can facilitate its best use and allow it to function exceptionally well.
Astris PME have a vast range of power wheelchair options., If you are looking for any support in this area or keen to know more, reach out to us at www.astris-pme.com.au or 1300 131 884.
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