Blood pressure measuring device

• US 4,429,700 A
• Filed: 02/02/1981
• Issued: 02/07/1984
• Est. Priority Date: 02/04/1980
• Status: Expired due to Fees

• Current Assignee: Honeywell BV A Subsidiary of Honeywell Incorporated
• Original Assignee: Honeywell BV (Honeywell International Inc.)
• Inventors: Wilden, Rolf, Thees, Richard
• Primary Examiner(s): Michell, Robert W.
• Assistant Examiner(s): Hanley, John C.
• Application Number:
  US06/230,829
• Time in Patent Office: 1,100 Days
• Field of Search: 128/677, 128/678, 128/680, 128/681, 128/682, 128/686
• US Class Current: 600/494
• CPC Class Codes: A61B 5/02141 Details of apparatus construction, e.g. pump units or housings therefor, cuff pressurising systems, arrangements of fluid conduits or circuits A61B5/02233, A61B5/0235 take precedence
• CPC Class Codes: A61B 5/02208 using the Korotkoff method

Abstract

An inflatable blood pressure cuff is pressurized with a vapor which is produced by heating a fluid which has a boiling point between 290° K. and 340° K. with an electric heating element. The heating element may comprise a PTC resistor which is disposed within the fluid. A piezoresistive element may also be disposed in the fluid to detect pressure pulses associated with Korotkoff sound.

Claims

1. A blood pressure measuring device comprising:

cuff means which function to apply pressure to a body part;

fluid reservoir means which communicate with the interior of the cuff;

a liquid having a boiling point between 290°

K. and 340°

K. disposed in the reservoir means;

means for measuring pressure in the cuff;

electric heating means disposed in the liquid which function to heat the liquid above its boiling point to increase vapor pressure in the cuff.

2. A blood pressure measuring device as claimed in claim 1, characterized in that the liquid comprises diethylether.

3. A blood pressure measuring device as claimed in claim 1, characterized in that the liquid comprises acetone.

4. A blood pressure measuring device as claimed in claim 1, characterized in that the liquid comprises a fluorinated hydrocarbon.

5. A blood pressure measuring device as claimed in claim 1, characterized in that the heating means comprises a PTC resistor.

6. A blood pressure measuring device as claimed in claim 1, characterized in that the means for measuring the pressure in the cuff comprises a temperature sensor for measuring the temperature of the liquid, a memory means for storing the temperature/vapour pressure characteristic of the liquid, and means for determining the vapour pressure associated with said liquid temperature from said stored temperature/vapour pressure characteristic.

7. A blood pressure measuring device as claimed in claim 6, characterized in that the temperature sensor comprises a PTC resistor.

8. A blood pressure measuring device as claimed in claim 1, further comprising a piezo-resistive element disposed in the liquid to detect the pressure variations caused by Korotkoff sounds.