By L. Michelle Tieszen, PT, and Thomas G. Johnston, PT
The Power of Selection Selecting an appropriate power mobility system can be a daunting task for even the most experienced clinicians. Many types exist with a multitude of features and costs to be considered. Understanding appropriate evaluation strategies and power mobility system components will allow you to work effectively with clients and durable medical equipment (DME) providers as you select an appropriate system. Information, assessment, recommendation, and teamwork are the keys to choosing the appropriate power mobility system. Data Gathering Asking the following questions will help guide your selection:
The next step is further assessment of the current mobility system, which should include a detailed review of the condition of all components of the mobility and seating systems. Follow this with an assessment of the client’s position, motor control, and mobility in his or her current system. examining propulsion When you observe wheelchair propulsion in the client’s current mobility system, watch for signs of trunk asymmetry and instability, as well as dysfunctional movement patterns. If the client experiences pain, tingling, or numbness in the upper extremities, document the time and distance that elapse before symptoms begin, as well as the resulting functional limitations. Such symptoms indicate a need to change the propulsion method and are useful in justifying the recommended system. To assess manual wheelchair mobility, be sure to include surfaces that the client encounters on a routine basis, such as sidewalks, gravel, grass, ramps, curb cuts, and padded carpet. Independence on a tile floor may not mean independence at home and in the community. Functional assessment of transfers, ambulation, manual wheelchair propulsion, and pressure-relieving abilities are important in selecting power mobility systems. Transfer abilities will influence the choice of seat height, armrests, and footrests. Ambulation ability will indicate the need for power mobility to achieve independence in the community and/or home environments. If a mobility system is not currently used, standard and lightweight manual wheelchair propulsion should be assessed to rule out the appropriateness of a manual system. The inability to reposition or complete independent pressure relief may indicate the need for a power tilt or a recline feature. Different funding sources will have different requirements for justification of power mobility. Knowledge of the reimburser’s requirements for power mobility will help as you gather the needed information during assessment. The physical assessment should include extremity strength, range of motion, and motor control, including coordination and spasticity. If a head support or head control option will be needed, assessment should include an examination of the head and neck as well. For seating and positioning recommendations, a mat evaluation should be completed and should include an assessment of unsupported sitting balance, determination of fixed and correctable trunk deformities, and maximum hip flexion/knee extension allowed while maintaining a neutral lumbar spine. The Recommendation Goes to... You are now ready to apply the assessment information to determine recommended power mobility system components for your client. You will need to identify recommendations in the following areas: Factory-set parameters (basic level). Electronic control of this type offers preset speed and acceleration/deceleration for forward, reverse, and turning.1 The user can adjust the speed; however, no individual driving parameters can be adjusted. Indications for this level of electronics include good postural control, good coordination, motor control for joystick manipulation, and stable medical condition. Programmable electronics (intermediate level). Electronic control of this type offers the ability to individually adjust parameters for speed, acceleration, and deceleration in all directions.1 This level of electronics is indicated when factory preset parameters have an adverse effect on postural control caused by poor sitting balance, spasticity, and abnormal reflexes. Programmable electronics (sophisticated level). In addition to adjustments offered at the intermediate level, adjustments can be made to joystick throw and sensitivity.1 Joystick input can be latched (ie, one command, such as a puff, activates forward drive until the stop command, such as a sip, is given), or momentary (ie, forward drive is activated while the joystick is manipulated, but stops when the joystick is released). Multiple device integration through the wheelchair electronics is possible in order to allow use of power tilt/recline/stand, communication devices, and environmental control units. a closer look at power bases Front wheel drive (FWD) power bases have good turning characteristics and ideal torque for pulling over objects in rough terrain. Rear wheel casters can result in fishtail at higher speeds; therefore, FWD chairs do not have the top speed of rear wheel drive (RWD) chairs. Midwheel drive power bases are best for clients with indoor environments and minimal to moderate community exposure. The center of gravity is closest to the drive wheels in this base, creating the tightest turning radius. Negative traits include difficulty climbing curbs and turning on uneven ground, especially when coupled with grass or brush. The front antitip wheels usually have minimal vertical travel and reduce drive wheel traction in deep ditches or ruts. (Some manufacturers claim 4 in. of front antitip wheel travel, allowing their bases to overcome this problem and climb small curbs.) Rear wheel drive power bases best handle the needs of clients in rural settings with demanding use patterns, due to increased stability at higher speeds. The deficits of RWD control are an increased turning radius and a chair that tries to push the casters through obstacles instead of pulling. Four wheel or all wheel drive systems are currently very expensive, but give outdoor enthusiasts a specific advantage in low traction and extreme environmental conditions. Disadvantages are increased weight, cost, and turning radius. These systems are difficult to medically justify and usually require payment by the client. Rigid frames are strong and durable but require the client to transfer in and out of vans or trucks via a lift or ramp. (Trailers or trailer-hitch systems used with cars can transport a rigid frame power chair, but require minimal ambulation or a caregiver to transport the chair.) Folding frames can be placed into mid- or full-size cars after removal of motors and batteries. A caregiver is usually needed to break down the chair and place the battery or motor combination in the vehicle. Frame length needs to be chosen after considering accessories, client driving preferences, and user weight, which would include the weight of the ventilator, ventilator tray, and seating system. Longer frames have more stable handling characteristics and are recommended for those who need ventilator trays or have greater than 250-pound user weight and need a heavy-duty frame. Shorter frames are lighter and have tighter turning radiuses. teamwork Once the necessary system components have been identified, it is time to begin equipment recommendation and trial. It is especially important to work as a team with the client, caregiver, and equipment provider. The equipment trial is important to test the recommendations and the client’s ability to safely use power mobility. It is best to try the type of power mobility system that is recommended and to closely simulate the client’s own environment. If a client is not immediately successful, a training period will often result in independence with power mobility. If joystick control is a problem, experiment with different programming of the electronic control parameters, joystick, or switch site modification to find a successful option. Assessment in the client’s environment may reveal safe and independent power mobility in familiar surroundings, even if supervision is necessary in unfamiliar environments. Be sure to listen to both positive and negative input from the client or caregivers. This will provide further opportunity to adjust the recommendations to meet their specific needs. If solutions are not readily apparent, enlist the help of the DME provider, who may suggest additional equipment and accessory options. The team now makes a final selection from the limited number of mobility systems that have all the needed components. L. Michelle Tieszen, PT, is clinical supervisor of outpatient physical therapy, and Thomas G. Johnston, PT, is a physical therapist on the spinal cord team, both at Madonna Rehabilitation Hospital, Lincoln, Neb. Reference
