Pulse comparator

Claim 2

Physiological monitoring apparatus for measuring the pulse width of an electrical signal occurring in the body of a patient comprising: a. sensing electrode means adapted to be operatively connected to the body of a patient; b. comparison means having first and second inputs aNd responsive to input pulse time duration for providing an indication of relative pulse width, said comparison means including means for maintaining said indication until another input pulse arrives; c. means for coupling said sensing electrode means to one input of said comparison means; d. means for producing a reference pulse of known time duration, said reference pulse producing means being coupled to adjustable means whereby the time duration of the reference pulse can be varied; and e. means for applying the output of said reference pulse producing means to the other input of said comparison means; f. whereby said comparison means provides an indication of whether the time duration of the signal occurring in the body of a patient is less than or greater than the duration of the reference pulse and said comparison means maintains the indication until another comparison is made.

Claim 3

Apparatus according to claim 1, wherein said reference pulse producing means is coupled through circuit means to said adjustable means whereby the time duration of the reference pulse is linearly proportional to the position of said adjustable means.

Claim 4

Apparatus according to claim 2, wherein said reference pulse producing means includes energy storage means whereby the time duration of the reference pulse is proportional to the current flowing through said energy storage means and wherein said circuit means includes a current source connected in controlled relation to said adjustable means and in controlling relation to said energy storage means whereby the magnitude of current flowing through said energy storage means is linearly proportion to the position of said adjustable means, said adjustable means being manually operable.

Claim 5

Apparatus according to claim 1, wherein said comparison means includes means responsive to an electrical quantity for providing a visual indication of relative pulse width.

Claim 6

Apparatus according to claim 1, wherein the signal occurring in the body of a patient is the artifact pulse from an implanted cardiac pacemaker and wherein said means coupling said electrode means to one input of said comparison means comprises pulse conditioning and sampling means for limiting the dynamic range of the artifact pulse and for generating a standardized pulse having a width which accurately represents the width of the pacemaker pulse.

Claim 7

Apparatus according to claim 5, wherein said pulse conditioning and sampling means comprises: a. amplifier means including a first stage having amplitude responsive gain control means for limiting the gain as applied to the leading edge of the artifact signal and including a second stage having a preferential gain for the trailing edge of the artifact signal; b. means for producing a pair of relatively sharp trigger pulses for each artifact pulse, the first trigger pulse occurring at a time corresponding to the beginning of the rise of said artifact pulse and the second pulse occurring at a time corresponding to the beginning of the fall of said artifact pulse; and c. pulse generating means for producing a relatively square pulse for each pair of said trigger pulses wherein the width of each square pulse is an accurate representation of the width of the corresponding pacemaker pulse which gives rise to said artifact pulse.

Claim 8

Physiological monitoring apparatus for measuring the pulse width of an electrical signal occuring in the body of a patient in the form of the artifact pulse from an implanted cardiac pacemaker, said apparatus comprising: a. sensing electrode means adapted to be operatively connected to the body of a patient; b. comparison means having first and second inputs and responsive to input pulse time duration for providing an indication of relative pulse width, said comparison means including means for maintaining said indication until another input pulse arrives; c. means for coupling said sensing electrode means to one input of said comparison meanS; d. means for producing a reference pulse of known time duration, said reference pulse producing means being coupled to adjustable means whereby the time duration of the reference pulse can be varied; e. means for applying the output of said reference pulse producing means to the other input of said comparison means whereby said comparison means provides an indication of whether the time duration of the signal occurring in the body of a patient is less than or greater than the duration of the reference pulse and said comparison means maintains the indication until another comparison is made; and f. means for conditioning the operation of said reference pulse producing means and said comparison means so that an indication is provided when the width of the artifact pulse deviates from the width of the reference pulse by a predetermined amount.

Claim 9

Physiological monitoring apparatus for measuring the pulse width of an electrical signal occuring in the body of a patient in the form of the artifact pulse from an implanted cardiac pacemaker, said apparatus comprising: a. sensing electrode means adapted to be operatively connected to the body of a patient; b. comparison means having first and second inputs and responsive to input pulse time duration for providing an indication of relative pulse width, said comparison means including means for maintaining said indication until another input pulse arrives; c. means for coupling said sensing electrode means to one input of said comparison meanS; d. means for producing a reference pulse of known time duration, said reference pulse producing means being coupled to adjustable means whereby the time duration of the reference pulse can be varied; e. means for applying the output of said reference pulse producing means to the other input of said comparison means whereby said comparison means provides an indication of whether the time duration of the signal occurring in the body of a patient is less than or greater than the duration of the reference pulse and said comparison means maintains the indication until another comparison is made; and f. means for conditioning the operation of said reference pulse producing means and said comparison means so that an indication is provided when the width of the artifact pulse deviates from the width of the reference pulse by a predetermined amount.

Claim 10

Apparatus according to claim 7, wherein said conditioning means comprises circuit means connected to said reference pulse producing means for initially changing the width of said reference pulse by said predetermined amount after said reference pulse is set equal to an initial artifact pulse by said adjustable means whereby if a subsequent artifact pulse changes in width by said predetermined amount an indication will be provided by said comparison means.

Claim 11

In physiological monitoring apparatus for measuring the width of an artifact electrical pulse in the body of a patient from an implanted cardiac pacemaker wherein a comparison means coupled to patient sensing electrode means and operatively connected to a reference pulse producing means provides an indication whether the time duration of a pacemaker artifact signal occurring in the body of a patient is less than or greater than the duration of the reference pulse, the improvement comprising means coupling said patient sensing electrodes to said comparison means in a manner limiting the dynamic amplitude comprising: a. a first amplifier stage having a relatively high input impedance and having signal responsive gain control means operatively connected thereto so as to provide a relatively small gain for the leading edge of an artifact pulse signal; and b. a second amplifier stage operating in an emitter follower mode so as to apply the full current capability of said second stage to the trailing edge of an artifact pulse signal thereby having a directional preference for said trailing edge.

Claim 12

In physiological monitoring apparatus for measuring the width of an artifact electrical pulse in the body of a patient from an implanted cardiac pacemaker wherein a comparison means coupled to patient sensing electrode means and operatively connected to a reference pulse producing means provides an indication whether the time duration of a pacemaker artifact signal occurring in the body of a patient is less than or greater than the duration of the reference pulse, the improvement comprising means coupling said patient sensing electrodes to said comparison means in a manner limiting the dynamic amplitude comprising: a. a first amplifier stage having a relatively high input impedance and having signal responsive gain control means operatively connected thereto so as to provide a relatively small gain for the leading edge of an artifact pulse signal; and b. a second amplifier stage operating in an emitter follower mode so as to apply the full current capability of said second stage to the trailing edge of an artifact pulse signal thereby having a directional preference for said trailing edge.

Claim 13

Apparatus according to claim 9, wherein said first amplifier stage comprises: a. a field effect transistor amplifier having gate, source and drain terminals; and b. signal responsive gain control means comprising a first resistor connected to said drain terminal, a capacitor connected to an electrical ground or reference, and a network connecting said first resistor to said capacitor and comprising the parallel combination of a second resistor and a germanium diode.

Claim 14

Apparatus according to claim 9 further comprising: a. sampling means connected to the output of said second amplifier stage for detecting the beginning of rise and the beginning of fall of the signal; and b. means connected to said sampling means for generating a standardized pulse having a width which accurately represents the width of the initiating pulse within the pacemaker which causes the voltage at the pacemaker output terminals which gives rise to the artifact signal.

Claim 15

Apparatus according to claim 11 wherein said sampling means comprises: a. differentiator means for producing positive-going and negative-going pulse spikes corresponding to the leading edge and trailing edge, respectively, of the artifact signal; b. differential amplifier means having one input connected to said differentiator means and the other input connected to an electrical reference or ground, said amplifier means having a feedback network to determine the derivative gain thereof, siad amplifier providing an output pulse at a time corresponding to when the artIfact signal begins to rise and another output pulse at a time corresponding to when the artifact signal begins to fall; and c. amplifier means connected to the output of said differential amplifier means for providing a positive current spike driving signal and a negative current spike driving signal corresponding to the beginning of rise and beginning of fall, respectively, of the artifact signal for triggering said standardized pulse generating means.

Claim 16

Physiological monitoring apparatus for measuring pulse width of an electricl signal occurring in the body of a patient in the form of the artifact pulse from an implanted cardiac pacemaker, said apparatus comprising: a. sensing electrode means adapted to be operatively connected to the body of a patient; b. comparison means having first and second inputs and responsive to input pulse time duration for providing an indication of relative pulse width; c. means for coupling said sensing electrode means to one input of said comparison means; d. means for producing a reference pulse of known time duration, said reference pulse producing means including energy storage means whereby the time duration of the reference pulse is proportional to the current flowing through said energy storage means, said reference pulse producing means being coupled through circuit means to adjustable means, said circuit means including a current source connected in controlled relation to said adjustable means and in controlling relation to said energy storage means whereby the magnitude of current flowing through said energy storage means is linearly proportional to the position of said adjustable means; e. means for applying the output of said reference pulse producing means to the other input of said comparison means whereby said comparison means provides an indication of whether the time duration of the signal occurring in the body of a patient is less than or greater than the duration of the reference pulse; and f. means for conditioning the operation of said reference pulse producing means and said comparison means so that an indication is provided when the width of the artifact pulse deviates from the width of the reference pulse by a predetermined amount.

Claim 17

Physiological monitoring apparatus for measuring pulse width of an electricl signal occurring in the body of a patient in the form of the artifact pulse from an implanted cardiac pacemaker, said apparatus comprising: a. sensing electrode means adapted to be operatively connected to the body of a patient; b. comparison means having first and second inputs and responsive to input pulse time duration for providing an indication of relative pulse width; c. means for coupling said sensing electrode means to one input of said comparison means; d. means for producing a reference pulse of known time duration, said reference pulse producing means including energy storage means whereby the time duration of the reference pulse is proportional to the current flowing through said energy storage means, said reference pulse producing means being coupled through circuit means to adjustable means, said circuit means including a current source connected in controlled relation to said adjustable means and in controlling relation to said energy storage means whereby the magnitude of current flowing through said energy storage means is linearly proportional to the position of said adjustable means; e. means for applying the output of said reference pulse producing means to the other input of said comparison means whereby said comparison means provides an indication of whether the time duration of the signal occurring in the body of a patient is less than or greater than the duration of the reference pulse; and f. means for conditioning the operation of said reference pulse producing means and said comparison means so that an indication is provided when the width of the artifact pulse deviates from the width of the reference pulse by a predetermined amount.

Claim 18

Apparatus according to claim 13, wherein said conditioning means comprises means operatively connected to said current source for initially changing the width of said reference pulse by said predetermined amount after said reference pulse is set equal to an initial artifact pulse by said adjustable means whereby if a subsequent artifact pulse changes in width by said predetermined amount an indication will be provided by said comparison means.

Claim 19

Apparatus according to claim 13, wherein said current source includes a transistor having base, emitter and collector terminals, the collector-emitter circuit of which is connected between a source of electrical energy and said energy storage means and wherein said conditioning means comprises: a. fixed resistance means; b. adjustable resistance means; and c. switch means for selectively connecting the base terminal of said transistor to said fixed resistance means or to said variable resistance means; d. whereby said switch means is first positioned to connect said fixed resistance means to said base terminal and said adjustable means is operated to set said reference pulse equal to an initial artifact pulse whereupon said switch means is moved to connect said adjustable resistance means to said base terminal thereby changing the width of said reference pulse by said predetermined amount determined by the magnitude of said adjustable resistance means whereby if a subsequent artifact pulse changes in width by said predetermined amount an indication will be provided by said comparison means.