Implantable tissue stimulator output stabilization system
First Claim
1. An implantable tissue stimulator for delivering stimulating pulses to selected tissue of a patient via one or more electrodes implanted on or near the tissue, comprising:
- pulse generator means for sequentially generating output pulses in a programmable pattern for application to the tissue, andcontrol loop means connected to the pulse generator means for measuring the magnitude of a predetermined parameter of selected ones of the output pulses at a predetermined point of the selected pulses and for adjustment of said magnitude to stabilize the value thereof for subsequent ones of the output pulses, the control loop means includingadjustment means responsive to measurements of said magnitude differing from a predetermined value for controlling the pulse generator means to adjust said predetermined parameter of the output pulses to reduce the difference to within a preselected amount.
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Accused Products
Abstract
Apparatus is disclosed for stabilizing the value of a parameter of the output pulses of a tissue stimulator, such as the magnitude of the current or the charge delivered in each output pulse to excite the cell membranes of the tissue to be stimulated. The apparatus measures the value of this parameter against target limits, and if either limit is exceeded, adjusts the value of a second parameter of the output pulses, such as voltage level or pulse width, to stabilize the value of the first parameter. The value of the first parameter may be measured by sampling thereof at a rate considerably less than the frequency of the output pulses, and the value of the second parameter then adjusted to bring the value of the first parameter within the target limits. Both current and charge stabilization modes of the pulse generating stimulator for efficient excitation of cell membranes of the selected tissue are described.
507 Citations
32 Claims
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1. An implantable tissue stimulator for delivering stimulating pulses to selected tissue of a patient via one or more electrodes implanted on or near the tissue, comprising:
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pulse generator means for sequentially generating output pulses in a programmable pattern for application to the tissue, and control loop means connected to the pulse generator means for measuring the magnitude of a predetermined parameter of selected ones of the output pulses at a predetermined point of the selected pulses and for adjustment of said magnitude to stabilize the value thereof for subsequent ones of the output pulses, the control loop means including adjustment means responsive to measurements of said magnitude differing from a predetermined value for controlling the pulse generator means to adjust said predetermined parameter of the output pulses to reduce the difference to within a preselected amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 23, 24, 25)
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15. Apparatus for stabilizing the value of the amount of electrical charge delivered in each of the output pulses of a neurostimulator for stimulating the excitable cell membranes of a selected nerve, comprising:
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measuring means for ascertaining the value of said electrical charge of the output pulses, comparing means responsive to the ascertained value for comparison thereof with a target value reflecting a desired limit on the value of said electrical charge, and adjusting means responsive to a discrepancy between the values under comparison for adjusting the duration of each output pulse to reduce the discrepancy and thereby stabilize the value of the electrical charge, whereby to control the output pulses of the neurostimulator to enhance the efficiency of stimulation of the nerve membranes, said adjusting means including means for immediately ending a pulse when the target value is reached.
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16. Apparatus for stabilizing the value of a parameter of the output pulses of a neurostimulator for stimulating the excitable cell membranes of a selected nerve, comprising:
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measuring means for sampling the value of said first parameter of the output pulses intermittently at separated cycles of the output pulses to ascertain the value of said parameter, comparing means responsive to the ascertained value of said parameter for comparison thereof with a target value reflecting a desired limit on the value of said parameter, and adjusting means responsive to a discrepancy between the values under comparison for adjusting the value of a second parameter of the output pulses related to the first-mentioned parameter to reduce the discrepancy and thereby stabilize the value of the first parameter, whereby to control the output pulses of the neurostimulator to enhance the efficiency of stimulation of the nerve membranes. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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26. Apparatus for stabilizing the value of a parameter of the output pulses of a neurostimulator for stimulating the excitable cell membranes of a selected nerve, comprising:
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measuring means for ascertaining the value of said parameter of the output pulses by performing a series of successive approximations of said parameter over a sequence of said output pulses, comparing means responsive to the ascertained value of said parameter for comparison thereof with a target value reflecting a desired limit on the value of said parameter, and adjusting means responsive to a discrepancy between the values under comparison for adjusting the value of a second parameter of the output pulses related to the first-mentioned parameter to reduce the discrepancy and thereby stabilize the value of the first parameter, whereby to control the output pulses of the neurostimulator to enhance the efficiency of stimulation of the nerve membranes.
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27. A method of stimulating body tissue, which comprises:
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implanting a stimulating electrode adjacent the tissue to be stimulated; applying electrical pulses to the electrode to stimulate the tissue; and continually adjusting the level of current or charge delivered in the applied electrical pulses to maintain the value thereof within a predetermined range of values deemed most efficient for exciting the tissue to be stimulated, including adjusting the voltage level or the duration of the output pulses, and further including modelling the charge delivered in each output pulse to be constant for compensation thereof according to the time constant of the excitable cell membranes of the tissue to be stimulated. - View Dependent Claims (28)
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29. A method of stimulating body tissue, which comprises:
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implanting a stimulating electrode adjacent the tissue to be stimulated; applying electrical pulses to the electrode to stimulate the tissue; and continually adjusting the level of current or charge delivered in the applied electrical pulses to maintain the value thereof within a predetermined range of values deemed most efficient for exciting the tissue to be stimulated, including adjusting the voltage level or the duration of the output pulses, and further including modelling the charge delivered in each output pulse to induce a threshold charge across the excitable cell membranes of the tissue to be stimulated which accounts for charge loss attributable to leakage from the membranes.
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30. Apparatus for stabilizing the magnitude of the current of the output pulses of a neurostimulator for stimulating the excitable cell membranes of a selected nerve, comprising:
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measuring means for measuring the magnitude of the current of selected ones of the output pulses by sampling the current magnitude at a predetermined point of the selected pulses, comparing means responsive to the measured value of the current magnitude for comparison thereof with a target value reflecting a desired limit on the current magnitude, and adjusting means responsive to a discrepancy between the values under comparison for adjusting the value of a second parameter of the output pulses related to current magnitude thereof to reduce the discrepancy and thereby stabilize the value of the current magnitude, whereby to control the output pulses of the neurostimulator to enhance the efficiency of stimulation of the nerve membranes. - View Dependent Claims (31, 32)
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Specification