Microprocessor-controlled multiplexed functional electrical stimulator for surface stimulation in paralyzed patients with safety enhancements

• US 5,092,329 A
• Filed: 05/22/1990
• Issued: 03/03/1992
• Est. Priority Date: 04/07/1989
• Status: Expired due to Fees

• Current Assignee: Sigmedics, Inc.
• Original Assignee: Sigmedics, Inc.
• Inventors: Graupe, Daniel, Arber, Amihadar
• Primary Examiner(s): Jaworski, Francis
• Assistant Examiner(s): MANUEL, GEORGE C
• Application Number:
  US07/527,381
• Time in Patent Office: 651 Days
• Field of Search: 128/419 R, 128/421, 128/422, 128/420.5, 128/420.6, 128/903, 128/423 W
• US Class Current: 607/66
• CPC Class Codes: A61F 4/00 Methods or devices enabling patients or disabled persons to operate an apparatus or a device not forming part of the body operating or control means for prostheses A61F2/48, A61F2/68
• CPC Class Codes: A61N 1/36003 of motor muscles, e.g. for walking assistance

Abstract

In accordance with the present invention, a functional electrical stimulation system enables upper-motor-neuron paraplegic patients and certain other paralyzed or partially paralyzed patients to stand and to take steps with the support of a walker in an independent fashion so that they are in control of the stimulation and, noting that they have very little or no sensation, that they still can obtain some feedback on the state of the system. In one embodiment, a compact and safe battery-operated stimulation system is provided that is of pocket size and that allows for non-invasive safe and controlled stimulation using skin surface electrodes.

The system of the present invention is a stimulation system for providing upper-motor-neuron paralyzed patients with capabilities of unbraced standing and unbraced walking, which consists of a single pulse power and amplifier that outputs various trains of stimulation pulses and which is totally under microprocessor generation and control, where the microprocessor'"'"'s microcomputer selectively performs multiplexing of the pulse trains and their selective alternate distribution to the various surface electrodes attached to the skin of the patient at the appropriate stimulation locations. It also controls pulse-width, pulse-duration, pulse-amplitude and pulse-shape.

Furthermore, the system can compute and activate (audible and/or visual) warning signals to warn the patient when the system is close to its maximal output. This would happen when muscle fatigue is such that no further increase in stimuli level can keep the patient upright. The system computes and outputs indications of the various stimuli levels to a visual display, and it provides automatic fail-safe and override capabilities to help ensure that the patient does not fall in case of major circuit or system failure or misactivation. This is a critical capability since this system will be used by paraplegics who lack sensation in their lower extremities.

Claims

1. An electrical stimulation system adapted for coupling to a patient, said system comprising:

a plurality of electrodes adapted to be coupled to locations at the right and left side of the lower part of the body of a patient,

input command means comprising a manual command switch circuit for providing mode input command signals;

controller means for storing and selectively outputting said control signal responsive to said input command signals;

pulse generator means for selectively outputting trains of pulses having selectively variable duration and pulse repetition frequency responsive to said control signal;

pulse amplifier means for selectively amplifying said pulse generator means output responsive to said control signal;

multiplexer means for selectively multiplexing outputs of said pulse amplifier means and alternatively between selected ones of said electrodes responsive to said controller means;

wherein said electrodes are wired in pairs as channels, wherein there are at least 4 channels, one adapted to be coupled to the right quadriceps muscle, one adapted to be coupled to the left quadriceps muscle, one adapted to be coupled to the right common peroneal nerve and one adapted to be coupled to the left common peroneal nerve; and

interconnection means, comprised of a polarized quick insertion device for coupling said input commands from said manual switch command circuit to said control means.

2. An electrical stimulation system adapted for coupling to a patient, said system comprising:

a plurality of electrodes adapted to be coupled to locations at the right and left side of the lower part of the body of a patient,

input command means comprising a manual command switch circuit for providing mode input command signals;

controller means for storing and selectively outputting said control signal responsive to said input command signals;

pulse generator means for selectively outputting trains of pulses having selectively variable duration and pulse repetition frequency responsive to said control signal;

pulse amplifier means for selectively amplifying said pulse generator means output responsive to said control signal;

multiplexer means for selectively multiplexing outputs of said pulse amplifier means and alternatively between selected ones of said electrodes responsive to said control means;

wherein said electrodes are wired in pairs as channel, wherein there are at least 4 channels, one adapted to be coupled to the right quadriceps muscle, one adapted to be coupled to the left quadriceps muscle, one adapted to be coupled to the right common peroneal nerve and one adapted to be coupled to the left common peroneal nerve;

interconnection means for coupling said input commands from said manual switch command circuit to said control means;

wherein the manual switch command switch circuit is mounted on the patient support device and permits only level adjustment; and

means for displaying the pulse output stimulus level for the channel having its level manually modified responsive to switch activation at the time of modification and for a short time thereafter.

3. An electrical stimulation system adapted for coupling to a patient, said system comprising:

a plurality of electrodes adapted to be coupled to locations at the right and left side of the lower part of the body of a patient,

input command means comprising a manual command switch circuit for providing mode input command signals;

controller means for storing and selectively outputting said control signal responsive to said input command signals;

pulse generator means for selectively outputting trains of pulses having selectively variable duration and pulse repetition frequency responsive to said control signal;

pulse amplifier means for selectively amplifying said pulse generator means output responsive to said control signal;

multiplexer means for selectively multiplexing outputs of said pulse amplifier means and alternatively between selected ones of said electrodes responsive to said control means; and

a portable casing within which said system is housed;

wherein said pulse generator means and said controller means are further characterized as comprising a single microcomputer, and an Analog to Digital Convertor (ADC), wherein said microcomputer selectively outputs through said ADC a single pulse train to said pulse amplitude and power amplifier, wherein said pulse power and amplitude is a single pulse amplifier, wherein the output of the pulse amplitude and power amplifier is multiplexed to distribute its output to at least 4 channels, wherein the multiplexer means is further comprised of solid state switch devices, wherein said control means switches modes of operation responsive to said input command means to provide a "stand" mode, a "take left step" mode, a "take right step" mode, and a "sit down" mode, wherein the levels of said pulse trains are ramped at an initial "stand" mode stand-up from an initial "sit-down" mode the levels of said pulse trains power, wherein said microcomputer receives said input commands from both an external switching array mounted on a patient support device that is coupled by a coupling to said casing enclosing said microcomputer, pulse amplifier, ADC and multiplexer, and, from a switching array mounted on said casing, wherein switching input commands are coupled from said external array including two sets of switches, one mounted on the right side of patient'"'"'s support device and one mounted on the left side of same, wherein said right side switches include one step switch to select command of "take right step" and one level switch to select command of both increasing pulse level for right quadriceps and for increasing pulse level for producing a right step, wherein increasing of pulse level for right quadriceps is commanded by a single short pressing of said level switch, wherein each such pressing produces a fixed increment increase in pulse level, and wherein a long duration pressing of said level switch beyond a predetermined duration selects a command to increase level of pulse to the common peroneal nerve to produce a step, wherein said left side switches do the same respectively for the left quadriceps and left step, wherein switching to command sit down is performed by long duration pressing for a duration longer than some predetermined duration, of a selected switch, and wherein once said sit down has been commanded, said control means delays execution of sit down command for different predetermined time duration;

wherein said switches on said casing are further comprised of separate switches for increasing level of pulses to right and left quadriceps muscles and level of pulses to common peroneal nerve to execute each step, wherein there is also a separate switch for sit down and one for stand, wherein there are also separate switches to command decrease of each of the above pulse levels and where there is also a system on-off switch, wherein said casing also includes a pulse level display that displays the level of the pulses to the channel whose level is manipulated at the time for a short predetermined time duration afterwards, and wherein the casing also includes a visual display of "low battery" and a warning display of maximal level of pulses to that quadriceps channel whose level is the highest, wherein the level at which said warning is activated is selectively determined responsive to the microprocessor, wherein there is a first audible alarm for low battery and another audible alarm, distinguishable from said first audible alarm, for maximal level of pulses that parallels the respective said visual alarm displays, the audible alarms being placed within said casing, wherein there are output sockets from the casing for output of said stimuli to the skin surface electrodes attached to the patient at the appropriate locations, wherein said microcomputer provides means for providing safety features, comprising means for returning the system to stand mode after sit down mode override means for returning to stand mode after each step mode, and of returning to stand mode responsive to said step mode being activated in excess of a predefined time, and which disallows right and left step from being activated simultaneously, wherein said safety means delays execution of sit down mode for a predetermined time duration and allows override of said sit down mode by pressing any switch during said time duration, said safety means providing means for returning the system to said stand mode whenever otherwise no take step or sit down command is received and allowed by said microcomputer, including when no command inputs at all are received by said microcomputer, wherein all interpretation of switch pressure duration and all other interpretations and setting of the various predetermined time durations are determined by the microcomputer, wherein all safety features are provided responsive to said same microcomputer and all outputs to and determination of warning except for low battery warning are set responsive to said microcomputer, wherein all overrides are set by said microcomputer, and wherein said microcomputer sets pulse repetition frequency, pulse width and pulse amplitude, and degree of overshoot responsive to said input commands;

wherein said visual warning is further characterized in that there exists a visual warning when sit down function has been activated and for a short time thereafter.

4. An electrical stimulation system for coupling to a patient, said system comprising:

a plurality of electrodes adapted to be coupled to locations at the right and left side for the lower part of the body of a patient,

input command means comprising a manual command switch circuit for providing mode input command signals;

memory for storing operational instructions and data;

control means for selectively outputting a control signal responsive to said input command signals;

pulse generator means for selectively outputting trains of pulses having selectively variable duration and pulse repetition frequency responsive to said control signal;

pulse amplifier means for selectively amplifying said pulse generator means output responsive to said control means;

multiplexer means for selectively multiplexing outputs of said pulse amplifier means alternatively between selected ones of said electrodes responsive to said control means; and

a portable casing within which said system is housed;

wherein said pulse generator means and said control means are further characterized as comprising a single microcomputer, and an Analog to Digital Converter (ADC), wherein said microcomputer selectively outputs through said ADC a single pulse train to said pulse amplitude and power amplifier, wherein said pulse power and amplitude amplifier is a single pulse amplifier, wherein the output of the pulse amplitude and power amplifier is multiplexed to distribute its output to at least 4 channels, wherein the multiplexer means is further comprised of solid state switch devices, wherein said control means switches modes of operation responsive to said input command means to provide a "stand" mode, a "take left step" mode, a "take right step" mode, and a "sit down" mode sit position, wherein at a subsequent "sit down" mode the levels of said pulse trains decreases to zero in a ramp manner to avoid sudden cessation of power, wherein said microcomputer receives said input commands from both an external switching array mounted on a patient support device that is coupled by a coupling to said casing enclosing said microcomputer, pulse amplifier, ADC and multiplexer, and, from a switching array mounted on said casing, wherein switching input commands are coupled from said external array including two sets of switches, one mounted on the right side of patient'"'"'s support device and one mounted on the left side of same, wherein said right side switches include one step switch to select command of "take right step" and one level switch to select command of both increasing pulse level for right quadriceps and for increasing pulse level for producing a right step, wherein increasing of pulse level for right quadriceps is commanded by a single short pressing of said level switch, wherein each such pressing produces a fixed increment increase in pulse level, and wherein a long duration pressing of said level switch beyond a predetermined duration selects a command to increase level of pulse to the common peroneal nerve to produce a step, wherein said left side switches do the same respectively for the left quadriceps and left step, wherein switching to command sit down is performed by long duration pressing for a duration longer than some predetermined duration, of a selected switch, and wherein one said sit down has been commanded, said control means delays execution of sit down command for a different predetermined time duration;

wherein said switches on said casing are further comprised of separate switches for increasing level of pulses to right and left quadriceps muscles and level of pulses to common peroneal nerve to execute each step, wherein there is also a separate switch for sit down and one for stand, wherein there are also separate switches to command decrease of each of the above pulse levels and where there is also a system on-off switch, wherein said casing also includes a pulse level display that displays the level of the pulses to the channel whose level is manipulated at the time for a short predetermined time duration afterwards, and wherein the casing also includes a visual display of "low battery" and a warning display of maximal level of pulses to that quadriceps channel whose level is the highest, wherein the level at which said warning is activated is selectively determined responsive to the microprocessor, wherein there is a first audible alarm for low battery and another audible alarm, distinguishable from said first audible alarm, for maximal level of pulses that parallels the respective said visual alarm displays, the audible alarms being placed within said casing, wherein there are output sockets from the casing for output of said stimuli to the skin surface electrodes attached to the patient at the appropriate locations, wherein said microcomputer provides means for providing safety features, comprising means for returning the system to stand mode after sit down mode override, means for returning to stand mode after each step mode, and of returning to stand mode responsive to said step mode being activated in excess of a predefined time, and which disallows right and left steps from being activated simultaneously, wherein said safety means delays execution of sit down mode for a predetermined time duration and allows override of said sit down mode by pressing any switch during said time duration, said safety means providing means for returning the system to said stand mode whenever otherwise no take step or sit down command is received and allowed by said microcomputer, including when no command inputs at all are received by said microcomputer, wherein all interpretation of switch pressure duration and all other interpretations and settings of the various predetermined time durations are determined by the microcomputer, wherein all safety features are provided responsive to said same microcomputer and all outputs to and determination of warnings except for low battery warning, are set responsive to said microcomputer, wherein all overrides are set by said microcomputer, and wherein said microcomputer sets pulse microcomputer, and wherein said microcomputer sets pulse repetition frequency, pulse width and pulse amplitude, and degree of overshoot responsive to input commands;

wherein said output sockets are fast connect.