Output pulse compensation for therapeutic-type electronic devices

• US 5,184,617 A
• Filed: 06/05/1990
• Issued: 02/09/1993
• Est. Priority Date: 06/05/1990
• Status: Expired

• Current Assignee: Encore Medical Asset Corporation (Enovis Corp.)
• Original Assignee: Staodyn, Inc. (Compeq Technology Company Limited)
• Inventors: Harris, Frank W., Owens, Alan R.
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): SCHAETZLE, KENNEDY
• Application Number:
  US07/533,293
• Time in Patent Office: 980 Days
• Field of Search: 128/421, 128/422, 128/419 PG, 128/419 R, 128/419 G, 128/732, 128/423 R
• US Class Current: 607/63
• CPC Class Codes: A61N 1/3603 Control systems

Abstract

Pulse compensation is disclosed for electronic devices capable of producing a pulse output signal suitable for therapeutic purposes with pulse compensation being automatically provided upon sensing of a change in the conditions being monitored. The electronic device, which preferably includes a micro-computer, has externally accessible pulse width and intensity controls for determining the width and amplitude of pulses then being delivered. Upon each sensing of a change in a monitored condition capable of causing user discomfort or possible injury, the intensity of the pulses then being delivered is quickly reduced and then gradually increased toward the full intensity requested by the intensity control. Pulse compensation is also provided when the pulse width is varied by the pulse width control to thereby automatically cause a corresponding change in the range of intensities of the pulses then delivered, based upon a nerve fiber strength-duration curve of the pulses, to thereby maintain the stimulation capability of the pulses substantially constant at a percentage of intensity as determined by the intensity control.

Claims

1. An electronic device for providing output pulses for therapeutic purposes, said device comprising:

electronic controller means providing control pulses;

voltage supply means providing a voltage output;

pulse output means including transistor means for receiving said control pulses and said voltage output and, responsive thereto, providing output pulses for therapeutic purposes having an intensity and pulse width subject to change due to the occurrence of predetermined condition variations; and

said electronic controller means including sensing means connected with said transistor means for sensing saturation of said transistor means indicative of the occurrence of a predetermined condition variation capable of causing user discomfort while said output pulses are being provided, and, responsive thereto, said electronic controller means causing intensity compensation of said output pulses by causing the intensity of said output pulses to be quickly reduced to a predetermined intensity level and then, upon completion of said reduction, causing the intensity level of said output pulses to be gradually increased toward the intensity level of said output pulse existing immediately prior to sensing of the occurrence of said predetermined condition variation.

2. The device of claim 1 wherein said electronic controller means allows the intensity level of said output pulses to be gradually increased over a predetermined period of time unless said electronic controller means senses the occurrence of a predetermined condition variation capable of causing user discomfort during said predetermined time period of gradual increase of the intensity level of said output pulses.

3. The device of claim 1 wherein said electronic controller means includes micro-computer means for causing generation of said control pulses and for effecting said intensity compensation of said output pulses.

4. An electronic device for providing output pulses for therapeutic purposes, said device comprising:

electronic controller means providing control pulses;

voltage supply means providing a voltage output;

pulse output means for receiving said control pulses and said voltage output and, responsive thereto, providing output pulses for therapeutic purposes having an intensity and pulse width subject to change due to the occurrence of predetermined condition variations;

pulse width control means for varying the width of said output pulses;

intensity percentage control means for varying the percentage of intensity of said output pulses; and

said electronic controller means including sensing means for sensing a predetermined condition variation establishing a change in the width of the output pulses by said pulse width control means, and, responsive thereto, causing a corresponding and predetermined change in the range of intensities of said output pulses based upon a strength-duration curve applicable to said output pulses, said change in the range of intensities of said output pulses being in a manner such that the percentage of intensity as established by said intensity percentage control means is substantially maintained.

5. The device of claim 4 wherein said electronic controller means causes said corresponding and predetermined change in the range of intensities of said output pulses to be such that the charge delivered per pulse of said output pulses is maintained substantially constant.

6. In an electronic device for providing output pulses for therapeutic purposes and having output means for producing said pulses that includes a transistor with a drain, output pulse compensation means comprising first means including sensing means connected with said output means for sensing the drain voltage of said transistor indicative of a change in at least one predetermined condition being then monitored and sample and hold means connected with said sensing means whereby said sample and hold means receives the sensed drain voltage of said transistor, and second means connected with said sample and hold means for causing a rapid decrease in the intensity level of said output pulses upon sensing of said change in at least one predetermined condition being then monitored, said second means, upon completion of said rapid decrease in intensity level, then causing the intensity level of said output pulses to be thereafter gradually increased over a predetermined time period toward the intensity level of said output pulses existing immediately prior to said rapid decrease.

7. The device of claim 6 wherein said compensation means causes said rapid decrease in the intensity level of said output pulses in response to a predetermined change condition capable of causing user discomfort or possible injury.

8. The device of claim 6 wherein said sample and hold means includes capacitor means for storing a voltage indicative of said sensed change in said predetermined condition being then monitored.

9. The device of claim 6 wherein said compensation means causes said gradual increase in the intensity level of said output pulses over a period of about two seconds.

10. An electronic device for providing output pulses for therapeutic purposes, said device comprising:

electronic controller means providing control pulses;

voltage supply means providing a voltage output;

pulse output means for receiving said control pulses and said voltage output and, responsive thereto, providing output pulses for therapeutic purposes, said pulse output means including transistor means; and

said electronic controller means including sample and hold means connected with said transistor means for sensing the drain of said transistor means and capacitor means for storing a voltage indicative of said drain, said electronic controller means receiving said voltage stored at said capacitor means and, responsive to a stored voltage indicative of the occurrence of a predetermined condition variation, causing intensity compensation of said output pulses by rapidly decreasing the intensity level of said output pulses and thereafter gradually increasing the intensity level of said output pulses over a predetermined period of time toward the intensity level of said output pulses existing immediately prior to said rapid decrease in intensity level.

11. The device of claim 10, wherein said transistor means is an analog control output transistor, and wherein said sample and hold means includes a gate transistor connected between said analog control output transistor and said capacitor means.

12. In an electronic device for providing a pulse output signal for therapeutic purposes with said electronic device having pulse width control means for varying the pulse width of said pulse output signal and intensity percentage control means for varying the percentage of intensity of said output pulses, pulses width compensation means comprising:

sensing means for sensing a change in the pulse width of said pulse output signal by said pulse width control means and providing an output indicative thereof; and

electronic means for causing a change in the range of intensities of said pulse output signal responsive to said output from said sensing means, with said change in the range of intensities of said pulse output signal being in a manner such that the percentage of intensity as established by said intensity percentage control means is substantially maintained, and with said change in the range of intensities of said pulse output signal being based upon a strength-duration curve applicable to said delivered pulses of said pulse output signal to thereby maintain the charge delivered per pulse of said pulse output signal substantially constant.

13. The pulse width compensation means of claim 12 wherein said electronic means of said pulse width compensation means is a part of a micro-computer controlled by a predetermined algorithm.

14. The pulse width compensation means of claim 13 wherein said electronic device is a TENS-type unit, and wherein said preselected algorithm follows a mathematical formula of I=19.6/(1-e.sup.(-0.00305×

PW-0.0664)), where I is current and PW is pulse width.

15. An electronic device for providing output pulses for therapeutic purposes, said device comprising:

pulse width control means;

amplitude percentage control means;

controller means connected with said pulse with control means and said amplitude percentage control means, said controller means providing control pulses each pulse of which has a width and an amplitude determined by said pulse width control means and said amplitude control means;

high voltage supply means for providing a high voltage output;

pulse output means for receiving said control pulses and said high voltage output and, responsive thereto, providing output pulses for therapeutic purposes; and

said controller means also providing pulse compensation for causing a change in the range of intensities of said output pulses responsive to a variation in said pulse width of said output pulses effected by said pulse width control means, with said change in the range of intensities of said output pulses being based upon a strength-duration curve applicable to said delivered output pulses to thereby maintain the charge delivered per pulse of said output pulses substantially constant, and with the change in the range of intensities of said output pulses responsive to variation in pulse width being in a manner such that the percentage of intensity established by said amplitude percentage control means is substantially maintained so that the intensity level delivered within said range of intensities is such that the delivered charge remains unchanged by a change in said pulse width control means.

16. The device of claim 15 wherein said device provides output pulses to a plurality of output channels, and wherein said pulse compensation is provided for each of said output channels.

17. The device of claim 16 wherein said device includes a separate amplitude control means for each of said output channels, with each of said amplitude control means providing a separate percent of intensity control for each said channel.

18. A method for providing output pulses for therapeutic purposes, said method comprising:

providing control pulses;

providing a voltage output;

providing an output having transistor means for receiving said control pulses and said voltage output and, responsive thereto, providing output pulses having an intensity and pulse width subject to change due to the occurrence of predetermined condition variations;

sensing the occurrence of saturation of said transistor means indicative of a predetermined condition variation capable of causing user discomfort while said output pulses are being provided; and

utilizing said sensed occurrence of said predetermined condition variation to cause intensity compensation of said output pulses by causing the intensity of said output pulses to be quickly reduced to a predetermined intensity level and then upon completion of said reduction, causing the intensity level of said output pulses to be gradually increased toward the intensity level of said output pulses existing prior to sensing of the occurrence of said predetermined condition variation.

19. The method of claim 18 wherein said method includes allowing the intensity level of said output pulses to be gradually increased over a predetermined period of time unless the occurrence of a predetermined condition variation capable of causing user discomfort is sensed during said predetermined time period of gradual increases of the intensity level of said output pulses.

20. A method for providing output pulses for therapeutic purposes, said method comprising:

providing control pulses;

providing a voltage output;

receiving said control pulses and said voltage output and, responsive thereto, providing output pulses having an intensity and pulse width subject to change due to the occurrence of predetermined condition variations;

providing pulse width control means for varying the width of said output pulses;

providing intensity percentage control means for varying the percentage of intensity of said output pulses; and

sensing of a predetermined condition variation established by varying the width of the output pulses by said pulse width control means, and responsive thereto, causing the corresponding and predetermined change in the range of intensities of said output pulses based upon a strength-duration curve applicable to said output pulses, said change in the range of intensities of said output pulses being in a manner such that said percentage of intensity as established by said intensity percentage control means is substantially maintained.

21. The method of claim 20 wherein said provided pulse compensation causes said corresponding and predetermined change in the range of intensities of said output pulse to be such that the charge delivered per pulse of said output pulses is maintained substantially constant.

22. A method for providing output pulse compensation in an electronic device providing output pulses for therapeutic purposes and having output means that includes a transistor with a drain voltage, said method comprising:

providing sensing means for sensing the drain of said transistor of said output means indicative of a change in at least one predetermined condition being then monitored;

providing sample and hold means for receiving the sensed drain voltage of said transistor indicative of said change in said predetermined condition then being monitored; and

causing a rapid decrease in the intensity level of said output pulses upon sensing of said change in said predetermined condition and then, upon completion of said decrease of intensity level, gradually increasing the intensity level of said output pulses over a predetermined time period toward the intensity level of said output pulses existing immediately prior to said rapid decrease.

23. The device of claim 22 wherein said method includes causing said rapid decrease in the intensity level of said output pulses in response to a predetermined changed condition capable of causing user discomfort or possible injury.

24. The method of claim 22 wherein said gradual increase in the intensity level of said output pulses occurs over a period of about two seconds.

25. A method for providing pulse width compensation in an electronic device providing output pulses for therapeutic purposes, said method comprising:

establishing a percentage of intensity within a range of intensities;

sensing a change in the width of the output pulses being then delivered;

determining a new range of intensities based upon a strength-duration curve for said output pulses that corresponds to said change in pulse width; and

providing output pulses having said changed pulse width with said output pulses having said established percentage of intensity within said then determined range of intensities of said output pulses maintained to thereby also maintain the charge delivered per pulse of said output pulses substantially constant.

26. The method of claim 25 wherein said method includes changing the percentage of the amplitude of said delivered pulses independent of any said pulse width change of said delivered pulses.

27. The method of claim 25 wherein said electronic device is a TENS type unit, and wherein said change of said range of intensities follows the mathematical formula of I=19.6/ (1-e.sup.(-0.00305×

PW-0.0664)), where I is current and PW is pulse width.