Apparatus for heating tissue with a photoplethysmograph sensor

• US 5,158,082 A
• Filed: 08/23/1990
• Issued: 10/27/1992
• Est. Priority Date: 08/23/1990
• Status: Expired due to Fees

• Current Assignee: Spacelabs, Inc. (OSI Systems Incorporated)
• Original Assignee: Spacelabs, Inc. (OSI Systems Incorporated)
• Inventors: Jones, Paul H.
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): NASSER, ROBERT L
• Application Number:
  US07/573,342
• Time in Patent Office: 796 Days
• Field of Search: 128/633, 128/665, 128/666, 356/41
• US Class Current: 607/113
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/1491 Heated applicators

Abstract

A method and apparatus for increasing the blood flow in a patient'"'"'s tissue by warming the tissue with heat generated by a semiconductor device mounted in a sensor. The amount of heat generated is controlled by varying either the magnitude or the duty cycle of the current that flows through the semiconductor device, with the amount of heat required determined by either the temperature of the sensor'"'"'s contact surface or the operating performance of the apparatus.

Claims

1. An apparatus for increasing blood circulation by heat the tissue of a patient, comprising;

a housing having a thermally conductive heat plate contacting the tissue;

a light source generating heat and light in response to current flow therein, said light source being directly mounted on and in thermal contact with an exposed surface of said heat plate so that heat is conducted form said light source directly to said heat plate, said light source;

sensor means thermally connected to said heat plate, said sensor means applying information on the temperature of said heat plate on an output port; and

current control means operatively connected to light source and to said output port, said current control means varying current to said light source in response to said temperature information said light source directing light away from said exposed surface of said heat plate so that when the exposed surface of said heat plate is placed in contact with said tissue, said tissue is heated by said heat plate and illuminated by said light source.

2. The apparatus of claim 1 wherein said light source is a light-emitting diode used to perform photoplethysmography.

3. The apparatus of claim 2 wherein said current control means varies the magnitude of current to said light-emitting diode.

4. The apparatus of claim 3 wherein said sensor means includes a thermistor.

5. The apparatus of claim 2 wherein said current control means varies the duty cycle of current to said light-emitting diode.

6. The apparatus of clam 5 wherein said sensor means includes a thermistor.

7. An apparatus for sensing a physical parameter and for increasing blood circulation by heating the tissue of a patient, comprising;

a housing having a heat plate;

light emitter diode thermally connected to said heat plate, said light emitter diode generating heat to heat said tissue and light for use in sensing said physical parameter in response to current flow therein;

a receiver optically connected to said light-emitting diode said receiver creating a received signal from said light from said limit-emitting diode, said received signal being indicative of said physical parameter;

reference means outputting a reference signal indicative of a desired temperature;

temperature sensing means generating a temperature signal indicative of the temperature of said heat plate;

comparison means connected to said temperature signal and to said reference signal, said comparison means comparing said temperature signal to said reference signal and outputting the difference as an error signal; and

current control means operatively connected to said light emitter diode and to said comparison means, said current control means controlling current flow in said light emitting diode in response to said error signal.

8. The apparatus of claim 7 wherein said current control means aries the magnitude of current to said light-emitting diode.

9. The apparatus of claim 8 wherein said current control means varies the duty cycle of current to said light-emitting diode.