EQUIPMENT FOR MEASURING AND DISPLAYING THE TIME LAPSE BETWEEN A GIVEN HEARTBEAT AND THE CORRESPONDING ARTERIAL PULSE

• US 3,734,086 A
• Filed: 03/24/1971
• Issued: 05/22/1973
• Est. Priority Date: 03/24/1971
• Status: Expired due to Term

• Current Assignee: Jerry Allan Sr. Phelps
• Original Assignee: Jerry Allan Sr. Phelps
• Inventors: Phelps, Jerry Allan Sr.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/127,573
• Time in Patent Office: 790 Days
• Field of Search: 128/2.5P,2.5E,2.5R,2.5T,2.6A,2.6B,2.6F,2.6G,2.5A
• US Class Current: 600/500
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: G04F 10/10 by measuring electric or magnetic quantities changing in proportion to time

Abstract

An apparatus for measuring the time interval between a heartbeat detected by an electrocardiographic detecting system and the corresponding peripheral pulse detected by a pulse sensing system is disclosed. Further features include a battery supply with a charging circuit and battery condition indicating means and a capacitor-type sample and hold circuit with constant current charging means and meter readout calibrated in pulse propagation time.

Claims

1. Equipment for measuring and displaying the time lapse between a given heartbeat and the corresponding arterial pulse at a peripheral area of the body of a patient, comprising:

A. a sample capacitor capable of accumulating voltage on a linear basis and operative, when reset by a voltage discharge operation, to start a given timing cycle;

B. a heartbeat-actuated capacitor-resetting apparatus for discharging and resetting said sample capacitor to start a given timing cycle, said apparatus producing an electrical signal representative of the QRS waveform content of a given heartbeat, said apparatus including 1. an ECG apparatus for detecting the electrical activity, which characterizes the cardiac ventricular contraction of said given heartbeat and for producing an electrical input signal representative of such electrical activity, 2. a bandpass filter connected to said ECG apparatus and operative to remove substantially all components of said input signal except the QRS waveform, 3. a monostable multivibrator connected to receive said QRS waveform from said bandpass filter and operative, in response thereto, to provide a step change in voltage, and 4. a reset circuit connecting said sample capacitor to said monostable multivibrator and operative momentarily, in response to said multivibrator voltage change, to discharge said capacitor and thus reset it for the start of said given timing cycle;

C. constant current supply and protective circuit means including 1. a constant current source connected to said sample capacitor for charging it during said given timing cycle with a voltage which is directly proportional to the elapsed time, and 2. a protective circuit connected to said sample capacitor and operative to limit its accumulation of voltage upon a failure to reset the sample capacitor at the end of said given timing cycle;

D. a field effect transistor switch connected to said sample capacitor, said switch normally being biased off;

E. pulse-actuated means for ending said given timing cycle by momentarily turning said field effect transistor switch on, said means including 1. a peripheral-pulse detection apparatus for producing an electrical peripheral pulse input signal which is representative of the arterial pulse corresponding to said given heartbeat, 2. a low pass filter connected to said peripheral-pulseapparatus for receiving and modifying said peripheral-pulse input signal by removing, from it, the dicrotic notch characteristic of a peripheral pulse waveform, and 3. a level detector connected to said low pass filter and to said field effect transistor switch and operative, in response to said modified peripheral pulse input signal, to provide a step change in the voltage which turns said transistor switch on momentarily; and

F. means for displaying a time lapse readout, corresponding to the linear voltage which accumulated on the sample capacitor during said given timing cycle, said means including 1. a hold capacitor connected to said field effect transistor switch and operative, when said transistor switch is momentarily turned on, to be charged with a voltage corresponding to the voltage which accumulated on said sample capacitor during said time lapse, 2. an operational amplifier buffer connected to said hold capacitor to maintain the voltage charge on said hold capacitor at a constant value and to provide a current output directly proportional thereto, 3. a meter for receiving an electrical input current and providing a vIsual time readout which is directly proportional to the input current it receives, and 4. a calibrate adjustment connected to the buffer and the meter to provide the meter with input current directly proportional to the elapsed heartbeat-to-pulse time.

2. a protective circuit connected to said sample capacitor and operative to limit its accumulation of voltage upon a failure to reset the sample capacitor at the end of said given timing cycle;

D. a field effect transistor switch connected to said sample capacitor, said switch normally being biased off;

E. pulse-actuated means for ending said given timing cycle by momentarily turning said field effect transistor switch on, said means including

3. a meter for receiving an electrical input current and providing a vIsual time readout which is directly proportional to the input current it receives, and

4. a calibrate adjustment connected to the buffer and the meter to provide the meter with input current directly proportional to the elapsed heartbeat-to-pulse time.