ELECTROMAGNETIC FLOWMETER

• US 3,659,591 A
• Filed: 08/24/1970
• Issued: 05/02/1972
• Est. Priority Date: 08/24/1970
• Status: Expired due to Term

• Current Assignee: Hans J. Broner, Henri Georges Doll
• Original Assignee: Hans J. Broner, Henri Georges Doll
• Inventors: Doll, Henri Georges, Broner, Hans J.
• Primary Examiner(s): Gaudet, Richard A.
• Assistant Examiner(s): Howell, Kyle L.
• Application Number:
  US05/066,240
• Time in Patent Office: 617 Days
• Field of Search: 128/2.5F,2.5R,2.5V,2.5P,2R 73/194EM
• US Class Current: 600/407
• CPC Class Codes: A61B 5/0265 using electromagnetic means, e.g. electromagnetic flowmeter
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: G01F 1/58 by electromagnetic flowmeters

Abstract

A noninvasive electromagnetic flowmeter particularly adapted to measure arterial blood flow in human beings is provided. A homogenous magnetic field is produced in the region of the artery under measurement by means of at least one large coil remote from the skin. Blood flow induced signals are sensed by electrodes placed on the skin adjacent the artery and fed to a measurement and control circuit. Electrocardiogram signals sensed by a second pair of electrodes placed on the body near the heart synchronize the operation of this system. A preferred embodiment of control and measurement system comprises a pair of auxiliary electrodes located where a strong and sharp cardiogram pulse can be repeatedly obtained to be used as a synchronizing signal and as a clock, at least one coil of large enough size having enough turns of wire to be adequate for the production of a strong and homogeneous magnetic field in the region of the artery under study, a source of DC current to feed that coil, means to reverse that DC current after a given number of heart cycles in accordance with a program controlled by the synchronizing signal, a pair of measuring electrodes placed on the skin adjacent the artery, an amplifier to amplify the signal appearing between said measuring electrodes, with filtering means to eliminate the DC unbalance of the electrodes and the high frequency noise, means to paralyze the amplifier and to reverse its output during each current reversal, and means synchronized by the synchronizing signal to average the pulsatile signal measured between the measuring electrodes during successive heart cycles so as to extract the repetitive wave shape of the blood flow pulses from the large random noise in which it is otherwise buried.

Claims

1. An electromagnetic flowmeter for measuring the blood flow pulse in a blood vessel of a living being comprising first sensing means adapted to be positioned on the being at a location where a strong and sharp cardiogram pulse can be repeatedly obtained, means connected to said first sensing means for providing a synchronizing signal and a clock, means for producing a strong and homogeneous magnetic field in the region of said vessel, means for reversing said magnetic field after a given number of heart cycles in accordance with a program controlled by said synchronizing signal, second sensing means adapted to be placed on said being at a location adjacent said vessel, amplifier means for amplifying the signal sensed by said second sensing means, means to paralyze said amplifier means and to reverse its output during reversal of said magnetic field and means synchronized by the synchronizing signal for averaging the pulsatile signal sensed by said second sensing means during successive heart cycles so as to extract the repetitive wave shape of the blood flow pulses from the random noise in which it is otherwise buried.

2. The electromagnetic flowmeter of claim 1 wherein said first sensing means comprises a pair of electrodes.

3. The electromagnetic flowmeter of claim 1 wherein said magnetic field producing means comprises an electromagnet having at least one coil of large enough size having enough turns of wire to produce said strong and homogeneous magnetic field.

4. The electromagnetic flowmeter of claim 3 including a source of DC current to feed DC current to said at least one coil.

5. The electromagnetic flowmeter of claim 4 wherein said magnetic field reversing means includes means to reverse the polarity of the DC current fed to said at least one coil repeatedly after a given number of heart cycles in accord with said program controlled by said synchronizing signal.

6. The electromagnetic flowmeter of claim 5 wherein said paralyzing means paralyzes said amplification means and reverses its output during reversal of the DC current fed to said at least one coil.

7. The electromagnetic flowmeter of claim 1 including filtering means for eliminating the DC unbalance of said second sensing means and for eliminating high frequency noise from the signal sensed thereby.

8. The electromagnetic flowmeter of claim 1 wherein said second sensing means comprises a second pair of electrodes adapted to be placed on the being adjacent the blood vessel under study.

9. The electromagnetic flowmeter of claim 1 wherein said averaging means comprises analog averaging means.

10. The electromagnetic flowmeter of claim 1 wherein said averaging means comprises digital averaging means.

11. The electromagnetic flowmeter of claim 1 including ground electrode means adapted to be positioned on said being remote from said first and second sensing means and connected to said amplifier means.

12. The electromagnetic flowmeter of claim 1 including means for maintaining the signal supplied to said averaging means substantially constant despite moderate changes of position by the being in the magnetic field.

13. An electromagnetic flowmeter for measuring the blood flow pulse in a blood vessel of a living being comprising a first pair of electrodes adapted to be positioned on the being at a location where a strong and sharp cardiogram pulse can be repeatedly obtained, means connected to said first pair of electrodes for providing a synchronizing signal and a clock, and electromagnet having at least one coil of large enough size and having enough turns of wire to be adequate for the production of a strong and homogeneous magnetic field in the region of the blood vessel under study, a source of DC current to feed DC current to said at least one coil of said electromagnet, means to reverse the polarity of said DC current after a given number of heart cycles in accordance with a progRam controlled by said synchronizing signal, a second pair of electrodes adapted to be placed on said being adjacent said blood vessel, an amplifier to amplify the signal appearing between said second pair of electrodes, filtering means for eliminating the DC unbalance of said second pair of electrodes and for eliminating the high frequency noise from the signal sensed thereby, means to paralyze the amplifier and to reverse its output during current reversal, and means synchronized by the synchronizing signal for averaging the pulsatile signal measured between said second pair of electrodes during successive heart cycles so as to extract the repetitive wave shape of the blood flow pulses from the random noise in which it is otherwise buried.

14. The electromagnetic flowmeter of claim 13 wherein said averaging means comprises analog averaging means.

15. The electromagnetic flowmeter of claim 13 wherein said averaging means comprises digital averaging means.