technical cons derations - veterans affairs · of a small business deciding to purchase a new...

Technical Cons derations

Powered Mobility and Its pl i cations

by C. Gerald Warren

Mr. Warren is President of C . Gerald Warren & Associates, a consultant firm in the field of technology applied torehabilitation . He is also Clinical Associate Professor, Department of Rehabilitation Medicine, and Affiliate AssociateProfessor, Center for Bioengineering, University of Washington, Seattle, WA . Mr. Warren is a past president of theAssociation for the Advancement of Rehabilitation Technology (RESNA).

INTRODUCTION

When we examine the factors that contribute toquality of life we see a combination of no less

than three : independence, vocation, and recreation.Like legs on a stool, all three need to be present,connected, and of similar length to provide stability.Among those things comprising independence, mo-bility and communication play the most criticalroles, and are functions that are basic to the qualityof a person's life.

Homo sapiens have certainly distinguishedthemselves as the most mobile animals to grace theface of the Earth . For man, mobility is a fundamen-tal part of living. Being able to move about, toexplore, under one's volitional control is a keystoneof independence . The degree of mobility individualshave is directly related to their level of indepen-dence; restricted mobility significantly affects theability to live a productive life.

Restricted mobility occurs in many forms andto many degrees . It must be looked upon as afunctional limitation of an individual rather than asa state or condition related to specific diagnoses.Just as the ability to be mobile varies in able-bodiedpersons, it also varies among people with disabili-ties, even within their diagnostic categories . Inproviding powered mobility, the process must focuson the person, clearly defining his or her restrictionsor limitations in function, and then determining how

best to reduce or eliminate those restrictions byintegrating powered equipment into their lives.Introducing powered mobility equipment into adisabled individual's life can truly be liberating forthat person. For those with no functional capability,it can be the difference between complete depen-dence and a great deal of independent mobility. Forthose with marginal capability, it can significantlyadd to their productivity and quality of their lives.

The powered wheelchair began with the applica-tion of automobile starter motors to the tubularcross frame wheelchair with power derived from anautomotive battery . The developments that followedall revolved around the basic cross frame tubularchair . As time went on and innovation continued tomeet the needs of severely disabled individuals, thecross frame of the wheelchair was removed and thespace beneath the seat became available for a varietyof equipment . Electronic control systems, communi-cation systems, respirators, recliners, and phrenicnerve stimulators all became part of the supportsystem that could be mounted on a poweredwheelchair . By the mid-1970s, where the resourceswere available, severely disabled individuals wereseated on a "pile of parts" which they were able tocontrol and so achieve a significant level of indepen-dent mobility . Concurrently, the "make Americaaccessible" plan was implemented and the domainof wheelchair users, particularly those using pow-ered equipment, expanded dramatically.

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WARREN : Powered Mobility

As sophistication in the design and variety ofaccessories and seating systems grew, so did the pileof parts. In 1982, new concepts were brought to-gether at the VA-sponsored workshop on specialadapted wheelchairs and sports chairs, WheelchairIII (1). As a result of this conference, many recom-mendations were made for research and develop-ment focusing on efficiency of the equipment, noisefactors, braking systems, and ride quality. In addi-tion, a philosophy evolved regarding the esthetics orthe cosmetics of a mobility system . This originatedthe concept of a powered chassis to which seats andaccessories were added in an orderly, modular form.

In the 1980s it is not uncommon to seeindividuals who are completely dependent in theirmobility functioning at very high levels, using anappropriate and well-integrated mobility system toindependently pursue their vocational, social, andleisure goals . The key to a successful implementa-tion of a powered mobility system does not, how-ever, lie in the technology itself—it relies primarilyon the needs and desires of the disabled individualto maintain or increase the quality of his/her life.The application of powered mobility equipmentmust be part of the total rehabilitation program. Itmust be integrated into the total plan which isdirected at specific functional outcomes.

The most obvious benefactors of poweredmobility are persons who are completely dependent(i .e ., without the equipment they are unable to movein their environment) . In some clinical settings, theseare the only people who are considered as candidatesfor powered mobility equipment . There are, how-ever, many manual wheelchair users and marginalwalkers who can gain considerable functional bene-fits from the use of powered equipment . These"marginal" ambulators do move in their environ-ments independently, but they may be greatlyrestricted in rate and distance due to their limitedcapability.

The marginal manual wheelchair user is some-one whose disability includes upper body weaknessand who depletes energy levels by propelling amanual wheelchair for more than very short dis-tances (such as those with mid- to low-level quadri-plegia). The resulting fatigue often compromisesother aspects related to the quality of their life . Thissituation can occur simply because the options to begained by using a powered system were not consid-ered during the prescription process . While such

individuals . should use manual equipment for neededexercise, recreation, and as a back-up in circum-stances where transportation or access is restricted,everyday mobility may be less stressful with apowered system. In some instances, the use ofmanual wheelchairs can be equated to use ofknee-ankle orthoses by individuals with paraplegia.For some, it soon becomes apparent that they wouldbe better off using a lightweight manual wheelchair.

These considerations illustrate the importanceof realistically assessing the functional objectives ofan individual and, when indicated, encouraging theuse of powered equipment . This can provide themarginal manual wheelchair user with an appropri-ate rate of ambulation as well as a means ofconserving his/her personal energies for activitiesother than mobility. The same considerations applyto the person with marginal ability to walk indepen-dently . Individuals with peripheral nerve disease,obesity, limb deficiency, or advanced age, all be-come candidates for a form of powered mobilitywhen the rate and/or range of their ambulationsignificantly restricts the quality of their lives.

The use of powered mobility for children hasbecome more prevalent in recent years, but notwithout controversy . In the early 1980s, the conceptof early mobility for severely disabled childrenemerged and was based on the logic that the patternof development of these individuals should approxi-mate that of able-bodied children . The interventionwas focused on reducing the limitations in the areasof social, cognitive, perceptual, and functionaldevelopment that were induced by lack of mobility.Clinical application of powered mobility for veryyoung children spurred the wheelchair industry torespond with new equipment . Research and develop-ment programs were established to provide disabledchildren with mobility at a time that would closelycoincide with the development of mobility in able-bodied children.

There are two main concerns regarding poweredequipment for young children : safety applications,and the potential adverse effects on the physicaldevelopment of a child who is provided early use ofpowered mobility. However, from clinical experi-ence, it is becoming clear that providing appropriatemobility to very young disabled children benefitstheir total development pattern and has a significantimpact on their potential to be more productiveindividuals .

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JRRD Clinical Supplement No . 2 : Choosing a Wheelchair System

GENERAL CONSIDERATIONS IN SELECTINGPOWERED MOBILITY EQUIPMENT

The assessment that leads to the decision aboutwhich equipment to purchase or recommend

is most important. This assessment must integratethe individual's functional needs, life plan, andavailable resources . The process is similar to thatof a small business deciding to purchase a newvehicle. Good decision-making would call forcareful analysis of all the functions the vehicleshould perform for the business. Then, dependingon the needs identified by the company, attentionwould be focused on the type of vehicle indicated—say, a compact car or a tractor trailer . Next, itwould be necessary to determine how the vehiclewould fit into the company's total business planby balancing functions to be gained with purchasecost . Finally, it would be necessary to answer thequestion : can and how will this acquisition be paidfor?

When applied to a recommendation for thepurchase of a wheelchair, this kind of approachrequires that a team of clinicians assist the client inthe process of evaluation . In projecting a realisticoutcome, the client must be knowledgeable aboutthe equipment, and be able to reconcile the cost ofachieving the objectives while maximizing the avail-able resources.

Because of the expense involved, the mostdifficult part of the delivery process may be estab-lishing a payment source and the needed level offunding . Third party payers often reel at the cost ofproviding powered mobility and its accessories.They have also historically witnessed the fact thatthe intended or desired outcome has frequently notbeen achieved . Such experience naturally leads themto be cautious, or at least conservative, in theirapproaches to funding powered mobility . This is adifficult position to try to reverse.

The conservative position of the third partypayers has been precipitated by the fact that themarket for durable medical equipment has beensupply (vendor) driven . The only way to regainthe confidence and support of the funding agenciesis through modification of the service deliveryprocess to make it more demand driven . This canonly be done by having clients and clinicians makeappropriate decisions about the equipment that isneeded to realize a reasonable functional outcome .

This outcome can be achieved by clearly defining theclient's needs, being informed about and selectingthe most appropriate equipment, and effectivelyutilizing all available technical, clinical, and finan-cial resources.

EQUIPMENT FOR THE MARGINAL WALKER

The design of equipment used by the marginalwalker is usually 3-wheeled or scooter-like. This

design provides excellent mobility without the"stigma" of a wheelchair and it is easy to mountand dismount . It is often used to compensate fora person's inability, for whatever reason, to com-fortably and safely travel distances outside thehome. It is not usually selected for exclusivein-home use because canes, walkers, or grab barsand rails are more suitable for moving over shortdistances.

The first consideration for equipment selectionis whether it will be used indoors, outdoors, or both.Equipment used exclusively indoors, at home, orin institutional or vocational settings, may not needto have the stability, power, distance, or durabil-ity requirements that outdoor use demands . How-ever, the vigor and functional needs of the usersshould influence the selection of indoor equipment.For example, the equipment for a geriatric indi-vidual to use going from bedroom to dining roomto therapy facilities in a retirement home woulddiffer significantly in function and cost from thatused by a young person with bilateral above-kneeamputation who was a shop supervisor in a largeindustrial setting . In some cases, a choice of lowperformance or high performance equipment mayhave to be made, or, in cases where adequateresources are available, two types of equipment maybe selected . Equipment used for high performanceindoors is often suitable for the low performancerequirements of outdoor use (i .e ., on relatively flat,uniform surfaces with moderate distance require-ments).

The selection of equipment for outdoor use isinfluenced most by the surfaces upon which it willoperate and the distances required to travel . Cli-matic conditions must also be considered becauseperformance of powered drive mechanisms areaffected significantly by moisture and temperature.Other considerations for this type of equipment are :

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seating for posture and trunk stability ; ease ofmounting and dismounting ; portability in ease ofassembly and disassembly ; and the weight and sizeof individual components which may need to belifted and stored in a car trunk.

The following case study illustrates how needsassessment and proper prescription can restorefunctional independence for an individual withmarginal walking capabilities.

Case #1 : Jackie M.Jackie M . is a 28-year-old female, diagnosed at

age 14 with Kugelberg-Welander's disease . She has ahistory of progressive motor weakness . At this pointin her life she is able to walk short distances onsmooth surfaces with the use of a cane . Jackie is alarge individual whose joints are being jeopardizedwith ambulation and she is at high risk of fracturesor joint trauma due to falling . Though weak, shehas good positional control of her upper extremitiesand her hand dexterity is excellent . She cannot,however, stand from a seated position indepen-dently.

Jackie is employed as a clerk-typist, full-time.She is currently experiencing a number of problemsat work which are directly related to her impairedmobility . She requires assistance getting in and outof the building and rising from her chair at her workstation . She is reluctant to ask for assistance andtherefore does not use the bathroom as often as sheshould . As a result she experiences periodic urinarytract problems . Jackie is unable to meet part of herjob requirement—moving to various locationsaround the workplace . Her employer will be relocat-ing to a carpeted facility, which will make it nearlyimpossible for her to walk at all.

Jackie's functional need made her an excellentcandidate for a 3-wheeled mobility device with apivoting and elevating seat . It was found that shecould independently come to the standing position ifthe seat could be elevated to 34 inches and locatedadjacent to a 54-inch high solid surface for her tolean on.

Providing her with this equipment makes Jackieindependent in the workplace . The installation of a54-inch shelf in the lavatory makes it possible forher to carry out her bladder functions (which sheperforms standing) . Now, Jackie only needs transferassistance from her husband when entering ordeparting her work facility .

EQUIPMENT FOR THE MARGINAL MANUALWHEELCHAIR USER

M any people interpret the change from a manualwheelchair to a powered wheelchair as an

admission or "indictment" of greater disabilityrather than as an option for increased capability . Itis often difficult to accurately assess or recognize thesecondary functional options that are realized whena person chooses to use a more efficient andeffective form of mobility . Often the perceived lossof physical prowess can be obviated by introducingthe person to wheelchair sports . The questions mustbe asked: What else might be achieved if the form ofmobility saves the wheelchair user's expense ofenergy? How much more work could get done?How much more "up time" could the individualhave? How much more productive could that timebe?

It is also important to consider the complica-tions and expense that are introduced by incorporat-ing powered mobility into a person's life . The costof providing and maintaining a powered system isapproximately three times that of a manual system.Some people who would like to use poweredequipment do not, simply because the expense of theinitial purchase combined with the need for suitabletransportation far exceeds available resources.

If they do use powered equipment, marginalmanual wheelchair users also need manual equip-ment for back-up and convenience . Some individu-als use the powered equipment only in fixed loca-tions and use the manual chair when traveling bycar . Others, where resources are available, use anappropriately equipped van.

It is not uncommon to find an individual whomoves from powered equipment back to manualequipment . This can occur when the gains intendedby the use of a powered chair is overridden by thebenefits of practicality or convenience offered byusing manual equipment.

A careful assessment of the individual canresult in a mobility plan that incorporates bothpowered and manual chairs . Based on functionalneeds, the powered equipment can range from lightduty equipment for use in a work place to full-sizedheavy duty high powered equipment for use in longrange indoor and outdoor mobility.

People in this ambulation category generallyhave good upper extremity control and moderately

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good trunk balance . They often desire high perfor-mance equipment, which is available through someof the major manufacturers, but can also can befound in kits which modify a chair to providegreater acceleration and top speed.

There is a population of disabled individualswho can use a hybrid approach to their mobilityneeds by combining manual and powered wheelchairequipment . Selecting the appropriate types of equip-ment for these individuals relies heavily on insightfulanalysis of their functional needs, looking particu-larly at how the use of powered mobility will impacttheir total lifestyle . The key to implementing such aprogram for an individual lies in identifying thefunctional or productivity gains that can be achievedand weighing them against the costs involved inproviding that equipment given the client's re-sources.

The case study below describes how one personcombined the use of manual and powered systems inorder to concentrate his energies on being produc-tive at work, while maintaining a more independentimage for leisure-time activities.

Case #2 : Russell G.Russell G . is a 20-year-old male with complete

quadriplegia at C 6-7 . He completed a comprehen-sive rehabilitation program and had been dischargedambulating with a lightweight wheelchair equippedwith pegged hand rims . He wanted to use themanual wheelchair in order to maintain and improvehis upper extremity condition . Russell independentlytransferred in and out of an automobile, laboriouslyloading and unloading the wheelchair.

Eighteen months after discharge he was spon-sored by the Division of Vocational Rehabilitationto attend a computer training program specificallyfor disabled individuals . The demands of the pro-gram began to take a toll on his stamina, and duringthe course he would on occasion allow an ambulat-ing student to give him a push from his car into thefacility and/or to and from the lunch room (overlow pile carpet).

Suggestions that he consider using a poweredwheelchair continued to be rejected because Russellperceived that using a powered wheelchair would bean admission of greater disability . Then, on fieldtrips to potential employers he began to realize theimpracticality of pushing the distances required toget from the parking facility into the building and to

his workplace. There were also considerable dis-tances to be travelled within the building, such as tomeetings and to the lunchroom . To efficientlyaccomplish these tasks (related solely to his mobilityand not to his job function) it would requireexcessive effort in his manual chair.

He eventually engaged in planning the moveinto a powered wheelchair system . Russell relocatedhis residence close to a wheelchair-accessible bus linethat connected with his employment location . Henow uses his electric wheelchair to go to and fromwork . But he continues to use his manual wheelchairfor all other social and recreational activities . Themanual wheelchair also serves as a backup when heencounters difficulties and/or breakdown with hiselectric wheelchair.

EQUIPMENT FOR THE SEVERELY DISABLEDINDIVIDUAL

People in this category are unable to indepen-dently transfer and/or are severely limited in

their ability to control mobility equipment . Theymust rely completely on their equipment for anylevel of independent mobility . With the properequipment, it is possible for someone capable ofonly one or two body motions to control a wheel-chair . The use of pneumatic switches makes itpossible for a person with only control of pressurein the oral cavity to operate powered equipmentwith a sip and puff control . Once fitted with theappropriate system, many people can have sufficientmobility to achieve high levels of independence . It isnot uncommon now to find people in the workplacewho have little more than breath or head control.These people can be assisted into their wheelchair inthe morning, provided with minimal assistancethroughout the day with feeding or leg bag evacua-tion, and at the end of a very productive day can beassisted from the wheelchair to their bed . Many suchindividuals are engaged in activities related to theireducation, vocation, and social leisure time.

Providing equipment for these individuals re-quires a highly integrated approach taking intoconsideration the physical requirements of the per-son's environment, the seating and positioning ofthe individual, the selection of the optimal controlmethod, and the integration of accessories andassociated equipment . Determination of a mobility

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system for an individual in this category is, as in allother wheelchair prescription cases, based on theanticipated functional needs and life objectives thatwill be pursued.

The first step in the process is to select the basicpowered base. The characteristics of additionalpowered equipment—such as recliners, communica-tion, and/or life support systems—must also beconsidered . This places further requirements on themobility system for both power and the space toaccommodate this equipment.

The next consideration is seating . The individ-ual must be provided with a seating system that willboth position him/her for optimal control of theequipment and also maximize the length of time theperson is able to remain seated in the wheelchair,which involves the factors of fatigue and tissueprotection . Determining the best positioning andposture of the individual in the wheelchair is ahighly specialized process that requires a well coor-dinated team approach . Proper seating is oftenfundamental to an individual's ability to operate thecontrol system . This is particularly true for individu-als who are cerebral palsied or head injured forwhich the processes of seating and control must beperformed together.

The factors in seating a severely disabled personto maximize "up time" are tissue protection, lowerextremity circulation, and threshold of fatigue.Tissue protection in persons with insensitive tissuerequires a seating surface that provides optimaldistribution of the pressures . However, the redistri-bution or unweighting of the load-bearing surfacesis an effective complementary method of assuringmaximum protection.

For the individual who is unable to performreliable pressure relief manually, powered recliningor tilting of the seat may be necessary . Poweredreclining mechanisms allows the individual to inde-pendently redistribute or decrease the pressure onthe weight-bearing surfaces and to rest residualtrunk and respiratory musculature . The reclinefunction is often combined with elevating legrestsand can assist in control of lower extremity fluidpooling. Many such users have demonstrated asecondary function of the recliner : using the motionto reposition themselves in space in a limited formof body language.

People who use reclining equipment have fre-quently complained that repeated reclining shifts

their bodies out of the normal stable position,causing a loss of sitting balance and poor position-ing. Sliding or stretching during the recline can alsocause unwanted spasticity and repeated reclining canwrinkle and bunch clothing, which of itself cancause uneven pressure distribution.

The reason for these difficulties arises from theearly design of the wheelchair, which used a simplehinge joint to attach the chair back to the frame . Inreclining a wheelchair with a standard hinge theperson tends to slide down the back of the seat.During elevation of the chair back, shear forcesbetween the person and the back usually prevent theperson from sliding back up to the original seatingposition . The sliding occurs because the location ofthe pivot points of the chair differ from the axis ofrotation of the person's body during the recline (2).

Many manufacturers now incorporate mecha-nisms into the recline system of wheelchair mecha-nisms that are designed to eliminate sliding either byallowing the chair back to slide with the person bytilting the entire seat, or by using mechanisms thatcause the chair back to follow the path of theperson. Studies have shown that the average dis-placement during recline is 11 centimeters.Chairbacks that provide a non-shear feature mustaccommodate displacement of approximately thismagnitude as the chair back goes through the reclinecycle (Figures la and ib).

A similar displacement problem can exist at theknee because the axis of rotation of the chair andthe knee joint may not coincide . The problem here isless severe, however, because the low mass of thelegs lets them slide without difficulty . A morecommon problem is encountered with the incorrectlength of the legrests . If they are too short, excessivepressure can be applied on the bottom of the feetwhen the legrest is elevated . Pressure on the feet andaccommodations made by adjusting the length ofthe legrest on the chair should always be checkedwhen using a system for reclining or elevating thelegs .

The use of non-shear reclining systems cansignificantly increase the up time of an individualand make it feasible and safe for that person tospend an entire functional day in a powered wheel-chair .

Control of a powered wheelchair can beachieved by harnessing any reliable motion anindividual may have . Motion in a plane can be used

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Figure is.Back displacement produced in a typical wheelchair . Reprinted from C .G. Warren et al. : Reduction of back displacementwheelchairs . Arch Phys Med Rehabil 63 :447-449, 1982.

to control a joystick and provide proportionalcontrol . Limited unidirectional motion can activatesingle switches which can be electronically inter-preted to perform a variety of functions . It ispossible to drive a wheelchair, slowly, with the useof a single switch . Voice recognition, whereby aperson speaks commands to control the chair, hasbeen used ; however, this approach has not beenwidely accepted due to cost, complexity, and reli-ability of operation.

The numerous sites that can be used forwheelchair control are shown in Figure 2 . Propor-tional control can be achieved using conventionaljoysticks when gross hand motion is available.When motion is limited, "short throw" joysticksneeding only 3/16 of an inch displacement of thesticks still result in full amplitude signal from thewheelchair controller . This approach can makefingertip control, chin control, and, in some cases,lip or tongue control possible.

Switching control of the wheelchair is madefeasible by the use of acceleration control circuitry.A sip and puff regimen uses a hard puff or sip on astraw connected to pneumatic switches to controlthe chair's forward and reverse and stopping func-tions . A soft sip or puff on the same straw activatesswitches that control the turning rate. Single-switchcontrol of a chair is also possible, whereby thefunctions are scanned and selected with a singleswitch (Figures 3a and 3b) . Such operation isnecessarily slow, but it does provide independentmobility for the severely disabled individual whomay have no other alternative.

Recently, microprocessors have been integratedinto wheelchair control systems that allow thecustom programming of performance features . Once

a person's motor capabilities have been analyzedwith regard to rate and degree of control and aphysical interface defined (i .e ., the method by whichthe person will activate the system), the controlfeatures can be custom-tailored to make the machinerespond appropriately.

When a severely disabled individual begins dailyactivities there are many accessories on board the

Figure lb.Average curve of back displacement versus recline angle for asample of quadriplegic subjects . Reprinted from C .G. Warrenet al . : Reduction of back displacement in wheelchairs . ArchPhys Med Rehabil 63 :447-449, 1982.

2-

0-10

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40 50

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ANGLE OF RECLINE(degrees from vertical)

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CURVE "A" - CONVENTIONAL RECLINER HINGE

CURVE °B°- WITH 4-BAR LINKAGE

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B

Figure 2.

Wheelchair control system . By positioning a switch or sensing device at some anatomical location, signals can be derived which mightbe employed to operate a wheelchair . This listing represents potential control sources ; controllers have been implemented to use manyof these sites:

A. Chin control. Worn as a collar, device requires very smalltravel (1/4 inch or less) to produce proportional control.B. Headrest control. By pushing straight back against theheadrest, a forward signal is produced . By rocking the head tothe left or right against the headrest, turn signals are generated.A separate switch needs to be activated to reverse the sense forbackward motion.C. Joystick . This operates using standard joystick format.D. Arm/elbow control. Movement of the elbow outwardand/or sliding of the arm forward and backward might be usedfor activation of switches or proportional signals.E. Head control. Direct use of forward/backward andleft/right movement of the head is employed.F. Shoulder position . Elevation and depression (or slump)provide forward/backward signals while protraction/retraction

of the shoulder provide the left/right signals.G. 1) Pneumatic (puff/sip) control . This system uses hard puffsand sips to control forward and backward velocities, while softpuffs and sips introduce proportional turns ; 2) Spoken control.A computer can analyze the words spoken and use them to"drive" the wheelchair ; 3) Mouth, tongue, lip control. Ahead-mounted chin-controller element can make use of smallmovements to provide proportional control.H. Foot control. A rocker plate could yield all four signals forwheelchair direction, or "gas pedal" type controls might beused.I. Knee control. Thrusting the knee inward or outward canprovide control signals.(Courtesy of DU-IT Control Systems Group, Inc ., Shreve, OH44676)

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JRRD Clinical Supplement No . 2: Choosing a Wheelchair System

OFF

SPEED

SELECT HIGHWHEN ON

REVERSE

DU-1 DIUNI AY

•

RIGHT

Figure 3a.Display for single switch scanning.(Courtesy of Z YGO Industries, Inc.)

wheelchair that may require control . Accessoriesmay include headlights, flashing lights, horns,alarms, tape recorders, fans, recline functions,telephone, and remote control actuators . The varietyof functions on the chair are selected through aswitch that controls a scanning display of thefunctions available . A second set of switches or ajoystick is then used to select a desired function.Since most individuals who use this type of equip-ment are not capable of operating more than onecontrol mechanism at a time, the functions areusually performed in serial.

Besides operating the wheelchair accessoryequipment, the control systems also incorporateremote control communication with environmentalsystems through radio frequency or infrared beams.Usually, the individual operates the features of anenvironmental control system through the samecontrol mechanism that is used for all other featuresof the wheelchair . Such a system enables the personto have remote control of anything switchable in hisor her environment, such as the telephone, inter-com, door latches, lights, AC receptacles, radios,television, and computer (Figure 4).

The survival rate of spinal cord injured peoplewho are respirator dependent has increased mark-edly because of the improved evacuation proceduresat accident sites and the specialized care nowprovided for severely disabled individuals . Those

who require life support systems, such as respiratorsand/or phrenic nerve stimulators, now can havethem mounted on board their wheelchairs . Thecritical nature of these life support systems requiresthat they be coupled to an emergency alarm systemthat can sense difficulty or malfunction and sum-mon assistance if needed . Commercial paging tech-nology can be applied, where a simple sensor detectsthe malfunction and a paging system transmits asignal to a receiving station to summon assistance.

Figure 3b.Direct select switches for directional control.(Courtesy of Z YGO Industries, Inc .)

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WARREN: Powered Mobility

Figure 4.Environmental control unit (ECU) utilizing cordless telephone technology . The MECCA system fully integrates into DU-ITwheelchair systems . This approach permits nearly all functions of the system to be located anywhere in the household . It places boththe selection and control processes as well as all of the telephone functions with the user in his wheelchair.(Courtesy of DU-IT Control Systems Group, Inc ., Shreve, OH 44676)

MECCA MOBILE SYSTEM

MECCA BASE SYSTEMOperator, MECCA-M and

wheelchair system D U t

AC APPLIANCES

VIABSR MODULES

ECU ACCESSORIES

VIA

BSR . MODULES

ECU ACCESSORIES

VIA

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DISPLAY MECCA BASE

SPECIALSECU (10)

This type of equipment requires lift-equippedvehicles for transportation . The most critical issue intransporting such individuals is adequate hold-downmechanisms in the vehicle . These mechanisms mustsecurely hold the wheelchair frame to the vehicle,and the individual must be secured to the wheel-chair . It is essential to remain aware of the fact thatthe wheelchair itself can constitute a mass 2 to 3times that of a person, and thus on impact it canbecome a formidable missile inside a vehicle.

The following case study demonstrates how aperson with a progressively disabling condition hasbeen able to continue his daily activities through theuse of a specially-equipped powered mobility sys-tem.

Case #3 : Bill T.Bill T. is a 39-year-old male, diagnosed with

Charcot-Marie-Tooth disease, a progressive heredi-tary neuropathy. The disease had progressed to thepoint where he was using a standard poweredwheelchair with a low back, swing-away legrests,and detachable desk arms . He used a lift-equipped

van with a translating driver's seat to which hetransferred from the powered wheelchair.

Bill was employed full-time by a state agency asan administrator of a major social service program.This position required him to spend a significantamount of time in and out of his office, driving15,000 miles a year.

Deterioration of his condition led to a moregeneralized weakness, which in turn affected hisposture, his ability to do pressure-reliefs, and inparticular his transfer abilities . He began experienc-ing persistent welling in his lower extremities. Hislevel of fatigue became extremely high . By the endof the day an independent transfer could take himup to 5 minutes . He found it necessary to retireimmediately after his evening meal . His generalhealth and well-being were deteriorating to the pointwhere he began to miss work.

A request to the Division of Vocational Reha-bilitation for post-employment services resulted inan evaluation focused on his mobility and transpor-tation system. It was recommended that he use apowered reclining wheelchair with elevating legrests

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and non-shear hinge mechanism operated through awheelchair accessory control system . This systemalso allows Bill to mount on the wheelchair a taperecording system for dictation and note-taking . Thepowered recline system allows him to sit in a relaxedposture and perform pressure reliefs while in meet-ings and at his desk talking on his speaker phone.Bill now has a great deal of flexibility finding waysto rest during the work day . The elevating legrestssignificantly improved the pooling of fluids in hislower extremities.

In addition, the van was modified to include adrop pan and hold-down system in the driver'sposition so that he could operate his vehicle from hiswheelchair. This eliminates what had been a verydifficult transfer activity . It also adds to his safetysince his wheelchair is now secured whereas in thepast it had simply been parked with brakes on whilethe van was in motion.

This implementation not only significantly im-proves Bill's effectiveness in the workplace but alsohas had a tremendously positive impact on thequality of his life by increasing his daily up time by3 and a half to 4 hours.

PEDIATRIC POWERED MOBILITY

n recent years increased attention has been paid toI the mobility needs of motor-impaired children

(3,4) . Proponents of powered vehicles for veryyoung people present strong reasons for introducingpowered mobility to children at a time in theirdevelopmental pattern that coincides as closely aspossible to when they would have begun indepen-dent mobility as an able-bodied child . The applica-tion of powered mobility can be as young as 24months.

This is a marked departure from the previouslyheld concept that powered mobility should only beprovided to adults because the value of providingthis equipment to children was offset by issues ofsafety and physical development . Moreover, it iscertainly true that with powered systems there arehigher costs, transportation problems, and accessi-bility issues. However, recent research clearly pointsto the advances that can be achieved in social,cognitive, perceptual, and functional developmentsof the child when early mobility is achieved .

Introducing powered mobility equipment foruse by a child must be done through a comprehen-sive evaluation of the child and family that isperformed by clinicians who understand how tomaximize the potential benefits of the equipment tothe child's life . There is a variety of equipment withmany options now on the market, such as 3-wheeledvehicles, carts .and buggies, and a miniature versionof the standard powered wheelchair.

Many systems are available for the child withlimited functional control . Selecting and interfacingthe control system with the child's abilities is one ofthe most crucial aspects, and should be done inconjunction with choosing the proper seating sys-tem. Proper positioning of the child is critical inachieving both operational success and safety.

All aspects of the child's growth and develop-ment need to be considered and incorporated intothe process . The evaluation must also consider thedevices that will be used in conjunction with themobility system, such as augmentative communica-tion, environmental control, and computers used inthe educational process . Of particular importance isintegrating the control of each piece of equipment toassure that it can be effectively operated with as fewrestrictions as possible . As with any child, there isthe ever-present concern for safety as independentmobility is explored . The disabled child learning touse powered mobility just presents a different set ofcircumstances.

ELEVATING AND STANDING MOBILITYDEVICES

In some vocational, educational, or perhaps evendomestic settings, an individual might benefit from

either elevating himself to various heights or movingaround in a vertical position . For example, anindividual may have to perform desk or keyboardactivities on the job and may also have to performcustomer service related activities at a 42-inchcounter. An elevating wheelchair seat will facilitatethese tasks.

There also is equipment on the market that willenable a person to be restrained in a standingposition and use a joystick to drive the poweredplatform upon which he/she stands . One such pieceof equipment also allows the individual to bend at

85


the waist and/or to move from standing to a nearlyprone position . Such equipment, however, is not foreveryone. But, it is appropriate in circumstanceswhere a needed function demands a capability thatcan only be provided by such equipment.

RECREATIONAL EQUIPMENT

There are many types of all-terrain vehicles thatare hand-controlled or that are easily adaptable

to hand controls . These vehicles can provide atremendous social leisure outlet for many disabledindividuals . Such vehicles have also been used invocational settings to move individuals throughterrain completely non-negotiable by standard pow-ered mobility equipment . This kind of equipmentcan provide opportunities for activities ranging fromcompeting on semi-professional race track circuits tohiking, hunting, fishing, or just taking a leisurely"walk in the woods ."

Organized competitive activities for poweredwheelchair users have been conducted on an ad hoc

basis in many parts of the country, usually inconjunction with a sports wheelchair event . Asinterest in powered wheelchair competitive eventsincreases, it is hoped it will precipitate the type ofdesign development that occurred with manualwheelchairs and the resulting growth of sports andrecreational activities.

CONCLUSION

The goal and responsibility of the prescriber of awheelchair must be to restore to the greatest

degree possible the individual's ability to pursuethe three quality of life factors: independence,vocation, and recreation. In some instances, thisis best accomplished by providing the option ofusing both a manual and a powered wheelchair.Giving a person the advantage of both optionsmay make the difference between self-reliance

and dependence on others . It can determine whetheror not a person is able to travel between homeand work or school without the assistance of others.It can greatly affect the quality and degree ofparticipation in many leisure activities, such asgoing out for a "walk" to the grocery store or justaround the neighborhood. Distances that seem shortor a bit of brisk exercise to an able-bodied walkermay cause total fatigue to those who must pushthemselves in a manual wheelchair . These areconsiderations that should not be overlooked by theprescriber.

Clearly, the powered wheelchair is not a symbolof further disability but a means to move aboutfreely while preserving vital energies for productivepursuits . This message must be conveyed to every-one whose disability requires the use of a wheelchairto carry out all or some of the everyday functions ofliving . However, the attitude that powered mobilityis only for those with severe disability is a conceptwidely held by both disabled individuals and thegeneral public. It need not be and should not be.Clinicians and other professionals who prescribewheelchairs have an opportunity to dispel this mythand, at the same time, improve the quality of life formany wheelchair users.

REFERENCES

1. Golbrahson FL, Wirta RW : Wheelchair III. Report of aWorkshop on Specially Adapted Wheelchairs and SportsWheelchairs. Bethesda, MD: Rehabilitation EngineeringSociety of North America, 1982.

2. Warren CG, Ko M, Smith C, Imre JV : Reducing backdisplacement in the powered reclining wheelchair . ArchPhys Med Rehabil 63 :447-449, 1982.

3. Trefler E, Kozole K, Snell E (Eds .): Selected Readings onPowered Mobility for Children and Adults with SeverePhysical Disabilities . Washington, DC : Association forthe Advancement of Rehabilitation Technology, 1986.

4. Jaffe K (Ed .) : Childhood Powered Mobility: Develop-mental, Technical, and Clinical Perspectives . Washington,DC: Association for the Advancement of RehabilitationTechnology, 1987 .

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