Motion compatible sensor for non-invasive optical blood analysis

• US 6,845,256 B2
• Filed: 02/21/2002
• Issued: 01/18/2005
• Est. Priority Date: 10/10/1996
• Status: Expired due to Term

• Current Assignee: Nellcor Puritan Bennett Incorporated (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett Incorporated (Medtronic Plc)
• Inventors: Mannheimer, Paul, Chin, Rodney, Flewelling, Ross
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US10/080,433
• Publication Number:
  US 20020103423A1
• Time in Patent Office: 1,062 Days
• Field of Search: 600/310, 600/322, 600/323, 600/330, 600/335, 600/336
• US Class Current: 600/323
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6833 Adhesive patches
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts

Abstract

A non-invasive optical sensor which uses the motion signal to calculate the physiological characteristic being measured. For pulse oximetry, a least squares or a ratio-of-ratios technique can be applied to the motion signal itself. This is made possible by selecting a site on the patient where variations in motion produce signals of two wavelengths which are sufficiently correlated. In particular, it has been determined that a sensor placed on a nail, in particular a thumbnail, exhibits the characteristics of having the red and infrared signals correlated when used for pulse oximetry, and the resulting signals correlate to arterial oxygen saturation.

Claims

1. A photometric device for processing detector signals representative of a blood property of a patient from a sensor attached to said patient, said sensor including a radiation emitter and a radiation detector, said monitor comprising:

a control unit configured to generate an activation signal to selectively activate said emitter; and

a processing unit configured to receive said detector signals and to process said detector signals utilizing at least two points on a motion signal that is part of said detector signal waveform produced by motion of said patient, a slope of said motion signal being used in an algorithm to calculate said blood property.