Activity and respiration monitor

• US 3,926,177 A
• Filed: 09/11/1972
• Issued: 12/16/1975
• Est. Priority Date: 09/11/1972
• Status: Expired due to Term

• Current Assignee: Valleylab Inc. (Medtronic Plc)
• Original Assignee: Edward V. Hardway Jr, William H. Holtman
• Inventors: Hardway, Edward V. Jr., Holtman, William H.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/287,844
• Time in Patent Office: 1,191 Days
• Field of Search: 128/2.5AM,2R,2S,2.6SB,2.08,2.1R,2.1Z 324/61QS,61P 340/265,272,273,278,279,280 317/246,DIG.1
• US Class Current: 600/535
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/6892 Mats
• CPC Class Codes: A61B 5/7242 using integration

Abstract

A contactless activity and respiration monitor is described which includes a resilient, capacitive pad, which may be a mattress, or a pad used with a mattress, having a capacitor therein responsive to the activity or respiration of a body lying on it. Electronic capacitance sensing circuitry is disclosed which provides an indication or alarm in the event of excessive activity or apnea, or low or high respiration rate. Readouts of respiration rate, and number of events of activity may also be provided. Circuits are disclosed for filtering out large static or relatively long term changes in the capacitance of the capacitive pad while maintaining the high sensitivity necessary to sense movements caused by respiration.

Claims

1. Apparatus responsive to movement of the body of a human or animal to provide an indication of a condition of such a body, comprising, in combination:

a resilient, capacitive pad adapted to respond to movement of such a body when disposed over the pad to provide a capacitance change, said pad including at least two electrodes extending beneath a substantial portion of the upper surface area of said pad, and a dielectRic between said electrodes;

electrical driving signal means;

capacitance sensing means;

means for connecting said driving signal means and said sensing means to said electrodes;

said sensing means being responsive to said capacitance change to provide an output signal representing said indication, said sensing means comprising an electronic high pass filter for substantially rejecting changes in capacitance of said pad of relatively long term as compared to the term of capacitance changes caused by the condition being indicated, and means for shortening the response time of said high pass filter when such activity exceeds a predetermined level.

2. The apparatus of claim 1 further including a first level detector responsive to capacitance changes caused by breathing of said body, and a second level detector responsive to capacitance changes caused by larger activity than breathing of said body.