CARDIAC MONITOR

• US 3,838,684 A
• Filed: 03/07/1973
• Issued: 10/01/1974
• Est. Priority Date: 01/20/1971
• Status: Expired due to Term

• Current Assignee: Barry Manuel, Harvey Pastan
• Original Assignee: Barry Manuel, Harvey Pastan
• Inventors: Manuel, Barry, Pastan, Harvey
• Primary Examiner(s): Gaudet, Richard A.
• Assistant Examiner(s): Cohen, Lee S.
• Application Number:
  US05/338,734
• Time in Patent Office: 573 Days
• Field of Search: 128/2.5P,2.5E,2.5H,2.5N,2.5R,2.5S 324/61P 317/246 340/200 73/398C
• US Class Current: 600/503
• CPC Class Codes: A61B 2562/02 Details of sensors specially adapted for in-vivo measurements
• CPC Class Codes: A61B 2562/0261 Strain gauges
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/02444 Details of sensor A61B5/02427 takes precedence

Abstract

The monitoring device is self-contained, compact and is preferably strapped about the wrist over the region where a radial pulse is normally detected. Heart rate and abnormalities in the heart beat rate are sensed by the device. Because no external connections are necessary to a power source, for example, the device is particularly useful for ambulatory patients suffering from various types of heart ailments. A pressure sensitive diaphragm sensor is held against the skin over the radial pulse region to sense the pulse wave transmitted from the heart. This pressure sensor couples to a mechanoelectrical transducer which converts the pressure pulse into an electrical analog pulse. A multivibrator, or the like, couples from the transducer and is used to square (digitize) the analog pulse. Logic circuitry receives a digital heart pulse from the multivibrator and is adapted to detect when the heart rate is either below a minimum predetermined rate or above a maximum predetermined rate. When either of these conditions exists an alarm signal is generated. Circuitry may also be included for those patients who may be expected to experience irregularities of the heart beat. This circuitry determines when heart beats have been dropped, for example.

Claims

1. A pressure sensor for detecting a pressure pulse and comprising;

a resilient capsule having means forming a hollow inner chamber, at least one conductive plate extending across the chamber and having an open area through the plate and being relatively immovable relative to the capsule, a flexible electrically conductive diaphragm disposed in the chamber and having an orifice therethrough. means for insulatedly spacing said plate and diaphragm, a fluid contained in the chamber and surrounding the plate and diaphragm, said orifice in said diaphragm being smaller than the open area through the plate and being smaller in comparison to the volume of fluid so that the diaphragm is relatively insensitive to slow pressure variations, and conductor means coupling from the plate and diaphragm for carrying electrical signal fluctuations, said sensor being responsive to a pressure pulse coupled to the resilient capsule to cause the diaphragm to deflect thereby varying the capacitance between the plate and diaphragm.

2. The pressure sensor of claim 1 comprising a second conductive plate disposed in the chamber and means for insulatedly spacing said second plate from said diaphragm and on a side of said diaphragm opposite the first plate, said conductor means also coupling from said second plate.

3. The pressure sensor of claim 2 wherein said second plate also has an open area therethrough, both plates having fluid surrounding them.

4. The pressure sensor of claim 3 wherein said means for insulatedly spacing includes a plurality of spacers.

5. The pressure sensor of claim 4 wherein the open area of both plates is defined by a plurality of holes.

6. The pressure sensor of claim 5 wherein the orifice is centrally disposed in the diaphragm.

7. The pressure sensor of claim 6 wherein said conductor means includes three wires, one connecting from the first plate, one from the second plate and one from the diaphragm.

8. The pressure sensor of claim 1 including a fixed capacitor, said conductor means also coupling from said capacitor.