PERFUSION MONITOR

• US 3,796,213 A
• Filed: 09/10/1971
• Issued: 03/12/1974
• Est. Priority Date: 09/18/1970
• Status: Expired due to Term

• Current Assignee: Frederick Richard Neason Stephens
• Original Assignee: Frederick Richard Neason Stephens
• Inventors: Stephens, Frederick Richard Neason
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/179,516
• Time in Patent Office: 914 Days
• Field of Search: 128/2L,2R,2.5A,2.5F,2.5M,2.5P,2.5Q,2.5R,2.5T,2.5V,2.6F
• US Class Current: 600/479
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/7242 using integration

Abstract

A perfusion monitor for monitoring blood flow in a body. A transducer, associated with a part of the body, generates signals representing pulse wave forms. The signals are fed to a circuit which generates output signals corresponding to pulse rate and the area under the pulse curve. These latter signals are then multiplied and the result integrated. A signal proportional to the integrated result is then fed to a perfusion index meter which displays a reading of the blood flow.

Claims

1. A perfusion monitor for monitoring blood flow in a body, comprising:

a, means for obtaining a first signal corresponding to a pulse curve;

b. means for determining pulse rate including means for generating a second signal for each pulse;

c. means for measuring the area under the pulse curve including means for generating a third signal proportional to the area under the pulse curve;

d. means for multiplying said second and third signals to produce a fourth signal;

e. means for integrating said fourth signal to produce a perfusion index; and

f. means for displaying a reading proportional to said index.

2. A perfusion monitor as claimed in claim 1 further including a direct reading pulse rate meter connected to said pulse rate determining means and wherein said display means includes a perfusion index meter.

3. A perfusion monitor as claimed in claim 1 wherein said means for obtaining includes at least one transducer adapted to be associated with a body.

4. A perfusion monitor as claimed in claim 3 wherein:

obtaining includes an amplifier, connected to said transducer, for amplifying pulse signals from said transducer;

b. said means for determining includes a band-pass filter, connected to said amplifier, for filtering unwanted noise from the amplified pulse signals, a trigger and monostable multivibrator circuit, comprising said second signal generating means, responsive to the output of said filter, a first integrator, connected to said filter through said circuit, for integrating the output of said filter and a pulse rate meter, responsive to the output of said first integrator, for indicating pulse rate;

c. said means for measuring includes a pulse amplitudE measurer, connected to said amplifier, for measuring the amplitude of the amplified pulse signals;

d. said means for multiplying includes a multiplier, connected to said measurer and said circuit, for multiplying said second and third signals;

e. a sensitivity control is connected to said multiplier;

f. said means for integrating includes a second integrator, connected to said multiplier through said sensitivity control, for averaging said fourth signal; and

g. said display means includes a perfusion index meter, responsive to the output of said second integrator, for indicating the flow of blood.

5. A perfusion monitor as claimed in claim 3 wherein said means for obtaining comprises:

a. a light source whose light adapted to be directed to the translucent vascular connective tissue of a body; and

b. a photoelectric cell responsive to the intensity of light reflected by blood within the connective tissue, said cell comprising said transducer.

6. A perfusion monitor as claimed in claim 3 comprising a plurality of transducers, said transducers being adapted to be associated at pairs of separated points upon the body whereby different readings may be fed to said display means.

7. A perfusion monitor as claimed in claim 6 wherein one transducer is adapted to be attached to a finger and another transducer is adapted to be attached to the pinna of the ear of a body.

8. A perfusion monitor as claimed in claim 1 wherein said display means includes a perfusion index meter having a central scale reading of 100 percent.