WHAT TYPES OF INTERFACE DEVICES ARE AVAILABLE FOR PROPULSION OF A MOTORIZED WHEELCHAIR IN A PATIENT HAVING C5 TETRAPLEGIA ?
B ) WHAT ARE THE PRESCRIPTION CRITERIA FOR EACH TYPE OF SUCH DEVICES ?
A 2 DEFINITION
A ) The term interface describes the mechanism for controlling the movement of a power wheelchair.
B ) Examples of interfaces include, but are not limited to, joystick, sip and puff, chin control, head control, etc. Interfaces are also called control input devices.
TYPES
A ) proportional interface is one in which the direction and amount of movement by the member controls the direction and speed of the wheelchair.
1 One example of a proportional interface is a standard joystick.
B ) A non-proportional interface is one which involves a number of switches. Selecting a particular switch determines the direction of the wheelchair, but the speed is pre-programmed.
1 One example of a non-proportional interface is a sip-and-puff mechanism.
INTERFACE DEVICES
1 CONTROLLER
A ) The term controller describes the microprocessor and other related electronics that receive and interpret input from the joystick (or other drive control interface) and convert that input into power output which controls speed and direction. A high power wire harness connects the controller to the motor and gears.
TYPES
1 A non-expandable controller has the following features:
A ) May have the ability to control up to 2 power seating actuators through the drive control (for example, seat elevator and single actuator power elevating legrests)
B ) (Note: Control of the power seating actuators though the Control Input Device would require the use of an additional component, an electronic connection between wheelchair controllers and power seating system motors.)
C ) Can accommodate only an integral joystick or a standard proportional remote joystick
D ) May allow for the incorporation of an attendant control.
2 An expandable controller is capable of accommodating one or more of the following additional functions:
A ) Other types of proportional input devices (e.g., mini-proportional or compact joysticks, touchpads, chin control, head control, etc.)
B ) Non-proportional input devices (e.g., sip and puff, head array, etc.)
C ) Operate 3 or more powered seating actuators through the drive control. (Note: Control of the power seating actuators though the Control Input Device would require the use of an additional component, an electronic connection between wheelchair controllers and power seating system motors.)
D ) An expandable controller may also be able to operate one or more of the following:
A separate display (i.e., for alternate control devices)Other electronic devices (e.g., control of an augmentative speech device or computer through the chair’s drive control)An attendant control
2 A harness describes all of the wires, fuse boxes, fuses, circuits, switches, etc. that are required for the operation of an expandable controller.
A ) It also includes all the necessary fasteners, connectors, and mounting hardware.
B ) A harness is separately billable in addition to an expandable controller both at initial issue and with complete replacement of the expandable controller.
3 An integrated proportional joystick and controller is an electronics package in which a joystick and controller electronics are in a single box, which is mounted on the arm of the wheelchair.
4 A remote joystick is one in which the joystick is in one box that is typically mounted on the arm of the wheelchair and the controller electronics (i.e., the box containing the electronics that connects the interface to the motor and gears).
A ) are located in a different box that is typically located under the seat of the wheelchair.
B ) The joystick is connected to the controller through a low power wire harness.
C ) A remote joystick may be used for either hand control, chin control, or attendant control.
REQUIREMENTS
A standard proportional remote joystick is one which requires approximately 340 grams of force to activate and which has an excursion (length of throw) of approximately 25 mm from neutral position. It can be used with a non-expandable or an expandable controller.
TYPES OF REMOTE JOYSTICK
1 A mini-proportional (short throw) remote joystick is one which can be activated by a very low force (approximately 25 grams) and which has a very short displacement (a maximum excursion of approximately 5 mm from neutral).
A ) It can only be used with an expandable controller.
B ) It can be used for hand or chin control or control by other body part (e.g., tongue, lip, fingertip, etc.).
2 A compact proportional remote joystick is one which has a maximum excursion of about 15 mm from neutral position but requires approximately 340 grams of force to activate. It can only be used with an expandable controller. It can be used for hand or chin control or control by other body part (e.g., foot, amputee stump, etc.).
5 A touchpad is an interface similar to the pad-type mouse found on portable computers.
VV IMP
A ) A hand control interface with multiple mechanical switches is a system of 3 to 5 mechanical switches which are activated by the person touching the switch.
B ) The switch that is selected determines the direction of the wheelchair.
C ) A mechanical stop switch and a mechanical direction change switch, if provided, are included in the allowance for this c
6 Specialty joystick handles are prefabricated joystick handles that have shapes other than a straight stick (e.g., U-shape or T-shape) or that have some other non-standard feature (e.g., flexible shaft).
7 A sip and puff interface is a non-proportional interface in which the user holds a tube in their mouth and controls the wheelchair by either sucking in (sip) or blowing out (puff).
A ) A proportional, mechanical head control interface is one in which a headrest is attached to a joystick-like device. The direction and amount of movement of the person’s head pressing on the headrest control the direction and speed of the wheelchair. A mechanical direction control switch is included in the component.
B ) VV IMP A proportional, electronic head control interface is one in which a person’s head movements are sensed by a box placed behind the user’s head. The direction and amount of movement of the person’s head (which does not come in contact with the box) control the direction and speed of the wheelchair.
C ) A proportional, electronic extremity control interfaceis one in which the direction and amount of movement of the user’s arm or leg control the direction and speed of the wheelchair.
D ) Interfaces typically have programmable control parameters for speed adjustment, tremor dampening, acceleration control, and braking.
INTERFACE DEVICES * ( SUMMARY - DEVICES ) FOR C5 TETRAPLEGIA
1 CHIN CONTROL
2 ELECTRONIC INTERACE ( speech generating devices )
3 ENHANCED JOYSTICK ( Q LOGIX EX )
4 HEAD RESTS
5 LAP TRAY WHEELCHAIR ATTACHMENT ( for trunk support )
6 ACTUATOR ( power seat elevation and stander feature )
7 SAFETY BELT / PELVIC STRAP / CHEST STRAP
8 CLOTHING GUARD
9 ULTRA LIGHT WEIGHT WHEELCHAIR ( less than 30 lbs )
10 ADULT TILT IN SPACE WHEELCHAIR ( greater than or equal to 20 degrees )
11 POWERED WHEELCHAIR CUSHION ( has an airpump )
12 FLAT FREE INSERT ( for pneumatic tyres )
B ) PRESCRIPTION CRITERIA FOR INTERFACE DEVICES
1 are generally prescribed for use by users who are unable to use a manual wheelchair
2 should be atleast mentally stable or should understand the technical aspects of such wheelchair
3 client satisfaction for propulsion devices
4 clients cognitive and perceptual capacity
5 should have no difficulties / disturbances in visual field - should see well
6 should have no hearing difficulties
7 capacity of upper limb - muscle power of all the individual muscle groups should be assessed
8 ASIA grading should be done
9 patient should have following abilities -
A ) to manipulate controls ( turning a key , adjust dials )
B ) to atleast turn head to look to the side or behind while turning
10 There should not be any history of seizures - should be atleast medically fit
11 There should not be any hx of drug abuse or liquor intake
12 Sufficient training should be provided before using these devices