Electrocardiographic and blood pressure waveform simulator device

• US 4,205,386 A
• Filed: 08/31/1978
• Issued: 05/27/1980
• Est. Priority Date: 03/01/1978
• Status: Expired due to Term

• Current Assignee: Conmed Corporation (Jefferies Financial Group, Inc.)
• Original Assignee: Valeron Corp.
• Inventors: Cook, Kenneth J., Ruszala, Frederick B.
• Primary Examiner(s): Gruber, Felix D.
• Application Number:
  US05/938,430
• Time in Patent Office: 635 Days
• Field of Search: 364/607, 364/608, 364/824, 364/825, 328/14, 328/187, 328/228, 328/185, 339/147 R, 338/220, 338/221
• US Class Current: 708/8
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/02156 Calibration means
• CPC Class Codes: A61B 5/319 Circuits for simulating ECG signals
• CPC Class Codes: G06G 7/26 Arbitrary function generators using Fourier series or other orthogonal functions G06G7/19; using curve followers G06K11/02
• CPC Class Codes: G06G 7/60 for living beings, e.g. their nervous systems ; for problems in the medical field
• CPC Class Codes: H01R 2107/00 Four or more poles
• CPC Class Codes: H01R 24/86 Parallel contacts arranged about a common axis
• CPC Class Codes: H03K 6/00 Manipulating pulses having a finite slope and not covered by one of the other main groups of this subclass circuits with regenerative action H03K4/00

Abstract

Apparatus for simulating waveforms utilized to check the operability of a remote display device. The apparatus includes a waveform generator for providing electrical signals representing simulated waveforms. An interface circuit for coupling the waveforms to the remote display device includes a bridge network having a plurality of resistive legs in which a variable resistance element is provided in one of the legs. The variable resistance element is coupled to the waveform generator. An excitation signal from the remote display device is coupled to an input of the bridge. The electrical signals from the generator causes the resistance of the variable resistance element to correspondingly vary and provide simulated waveforms at the output of the bridge network to the remote display device. According to another aspect of this invention, the device simulates both electrocardiographic and blood pressure waveforms, with the beginning of the blood pressure waveform being delayed from the beginning of the electrocardiographic waveform so that the waves are provided in a timed sequence corresponding to waveforms that would ordinarily be supplied by a live patient. An interconnection device is also supplied for coupling the simulator device to a blood pressure monitor, with the interconnection device automatically compensating for signal variations between a variety of blood pressure monitors so that the simulator device can be universally employed.

Claims

1. Apparatus for simulating waveforms utilized to check the operability of a remote display device, said remote display device providing an excitation signal which is normally coupled to a transducer for sensing physical characteristics of a live patient, said apparatus comprising:

(a) generator means for providing electrical signals representing simulated waveforms; and

(b) an interface circuit for coupling said waveforms to the remote display device, said interface circuit including;

(1) means defining a bridge network having a plurality of resistive legs, and a variable resistance element in one of said legs coupled to said generator means;

(2) means for coupling the excitation signal from the remote display device to an input of said bridge network;

(3) means for coupling an output of said bridge to the remote display device whereby said electrical signals from said generator means cause the resistance of said variable resistance element to correspondingly vary and unbalance the bridge network to provide said simulated waveforms to the remote display device.

2. The apparatus of claim 1 wherein said variable resistance element is a photosensitive device optically coupled to a light emitting diode (LED).

3. The apparatus of claim 2 wherein said interface circuit further comprises:

transistor means coupled between said generator means and said interface circuit for regulating the amount of current to the LED in response to said electrical signals from the generator means.

4. The apparatus of claim 3 wherein said interface circuit further comprises:

a source of electrical potential coupled to said transistor means, and a series connected potentiometer for initially adjusting the amount of current to the LED in order to zero the output of the bridge network.

5. The apparatus of claim 4 wherein said transistor means is a field effect transistor having gate, drain and source regions;

said gate region being coupled to said generator means, said source region being coupled to said potentiometer, and said drain region being coupled to said source of potential.

6. The apparatus of claim 5 wherein said interface circuit further comprises:

a plurality of resistance means each having a different resistance value; and

switch means for selectively coupling one of said resistance means to one leg of the bridge network to thereby unbalance the bridge and change the amplitude of the waveforms to the remote display device.

7. The apparatus of claim 6 wherein said means for coupling comprises:

a cable for interconnecting said apparatus with said remote display device, said cable having a plurality of conductors therein including first and second conductors for supplying said excitation signal to the bridge network, third and fourth conductors for coupling the bridge output signal to the remote display, and wherein each of said resistance means have one end commonly connected to said first conductor in the cable and their other ends coupled to said switch means.

8. The apparatus of claim 7 wherein the resistance value of said resistance means is chosen to modify the amplitude of the bridge output signal to represent various static pressure readings depending upon the type of the remote display being utilized.

9. The apparatus of claim 8 wherein said plurality of resistance means comprises four in number and wherein the resistance value of the first resistor has a value to modify said bridge output signal to provide a static pressure reading equivalent to 100 millimeters of mercury, the resistance value of said second resistor has a value to modify the bridge output signal to provide a static pressure reading equivalent to 80 millimeters of mercury, the resistance value of said third resistor has a value to modify the bridge output signal to provide a static pressure reading equivalent to 50 millimeters of mercury, and wherein said fourth resistor has a resistance value to modify the bridge output signal to provide a static pressure reading equivalent to 15 millimeters of mercury.

10. The apparatus of claim 9 wherein said second cable conductor includes a serially connected resistor therein to maintain a constant voltage at the input of said bridge network regardless of the level of the excitation signal from the remote display.

11. Apparatus for simulating electrocardiographic and blood pressure waveforms utilized to check the operability of an electrocardiogram machine and a blood pressure monitor, respectively, said apparatus comprising:

first generator means for providing a simulated electrocardiographic waveform segments;

second generator means for providing simulated blood pressure waveforms; and

control means coupled between said first and second generator means for automatically initiating said blood pressure waveform after a predetermined number of the electrocardiographic waveform segments have been generated so that said electrocardiographic and blood pressure waveforms are provided in a time sequence corresponding to waveforms that would ordinarily be supplied by a live patient.

12. The apparatus of claim 11 wherein said first and second waveform generator means includes clock means for providing driving pulses for driving said waveform generator means.

13. The apparatus of claim 11 wherein said first generator means comprises:

a first counter having a plurality of stages which are sequentially activated by said clock pulses;

a plurality of analog signal shaping circuits for generating the electrocardiographic waveform segments, each having an input and output, with each input connected to a stage of the counter; and

summing means connected to the outputs of the analog signal shaping circuits whereby the summing means provides a simulated electrocardiographic waveform at its output.

14. The apparatus of claim 13 wherein said second generator means comprises;

a second counter having a plurality of stages which are sequentially activated by said clock pulses;

a plurality of analog signal shaping circuits each having an input and output, with each input connected to a stage of said second counter; and

second summing means connected to the outputs of said analog signal shaping circuits whereby the second summing means provides a simulated blood pressure waveform at its output.

15. The apparatus of claim 14 wherein said control means further comprises:

a first flip-flop having set and reset inputs, and an output;

means for coupling the output of the first flip-flop to an enabling input of said second counter; and

means for coupling the set input of said first flip-flop to an intermediate stage of said first counter thereby delaying the beginning of the blood pressure waveform with respect to the beginning of said electrocardiographic waveform.

16. The apparatus of claim 15 wherein said output stages of the first counter are connected to analog signal shaping circuits for providing P, Q, R, S, and T electrocardiographic waveform segments.

17. The apparatus of claim 16 wherein said intermediate stage of the first counter is that stage which is coupled to the analog signal shaping circuit for providing the S electrocardiographic waveform segment.

18. The apparatus of claim 17 which further comprises:

a second flip-flop having set and reset inputs, and an output;

means for coupling the last stage of said first counter to the set input of said second flip-flop;

means for coupling the output of said second flip-flop to a disabling input of said first counter;

monostable means for providing an output pulse of a given width upon receipt of a trigger pulse at its input;

means coupling the last stage of said second counter to the input of said monostable means to provide the trigger pulse when said last stage of the second counter is activated; and

means for coupling the output pulse of said monostable means to the reset input of said first flip-flop, the reset input of said second flip-flop, a disabling input of said clock means, and to a disabling input of said second counter means whereby to regulate the periods between the electrocardiographic and blood pressure waveforms.

19. The apparatus of claim 18 wherein said monostable means further comprises:

means for adjusting the width of the output pulse from said monostable means to thereby change the periods of said electrocardiographic and said blood pressure waveforms.

20. An interconnection device for interconnecting a blood pressure monitor and a blood pressure waveform simulator device, with said blood pressure monitor providing an excitation signal and including means for receiving an input signal, said interconnecting device comprising:

a cable having a plurality of conductors;

a first connector means on one end of said cable having terminals for coupling said conductors to the blood pressure monitor;

a second connector means at the other end of the cable having terminals for coupling said conductors to said simulator device; and

a plurality of resistors having first and second end portions, the first end portions of the resistors being commonly connected to one of the conductors for supplying the excitation signal from blood pressure monitor to the simulator device, the other end portions of the resistors each being coupled to a separate terminal in one of said connectors to provide alternative conductive paths from the blood pressure monitor to said simulator device.

21. The device of claim 20 wherein said plurality of conductors comprise at least four in number in which the first and second conductors supply said excitation signal to the simulator device, and in which third and fourth conductors couple the output signals of the simulator device to said blood pressure monitor.

22. The device of claim 21 which further comprises:

an additional resistor serially connected with said first conductor, said resistor having a resistance value such that a portion of said excitation signal from the blood pressure monitor is dropped thereacross.

23. The device of claim 22 wherein said plurality of resistors each have different resistance values which are chosen to provide a plurality of different static pressure readings from said simulator device to said blood pressure monitor.

24. The device of claim 20 wherein said second connector means is adapted to be coupled to an interface network in said simulator device, said interface network including a resistive bridge network having a plurality of resistive legs.

25. The device of claim 24 wherein said plurality of resistors comprises four in number, and wherein when coupled to one of the resistive legs of said interface network the first resistor conditions said simulator device to provide a static pressure reading corresponding to 100 millimeters of mercury, said second resistor conditions said simulator device to provide a static pressure reading of 80 millimeters of mercury, said third resistor conditions said simulator device to provide a static pressure reading of 50 millimeters of mercury, and said fourth resistor conditions said simulator device to provide a static pressure reading of 15 millimeters of mercury.