Motion compensation in a sensor

• US 8,483,788 B2
• Filed: 02/28/2010
• Issued: 07/09/2013
• Est. Priority Date: 02/28/2010
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Miller, Mark C., Haisley, Charles, Klomhaus, Jill T., McKenna, Edward M., Van Slyke, Braddon M.
• Primary Examiner(s): Laballe, Clayton E
• Assistant Examiner(s): Smith, Linda B
• Application Number:
  US12/714,531
• Publication Number:
  US 20110213226A1
• Time in Patent Office: 1,227 Days
• Field of Search: 600/323, 600/310, 600/104
• US Class Current: 600/323
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/061 Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body A61B1/00158 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured

Abstract

A system and method for compensating for movement in a sensor. A sensor may include an emitter configured to transmit light, a detector configured to receive the transmitted light via a respective light path, and an accelerometer configured to measure a change in distance between the detector and the emitter. The sensor may transmit the measurements relating to the change in distance between the detector and the emitter to a pulse oximetry monitor. The pulse oximetry monitor may generate an attenuation factor corresponding to the change in the distance between the detector and the emitter that may be used to compensate for movement in a sensor when calculating physiological parameters of a patient.

Claims

1. A pulse oximetry system comprising:

a sensor assembly comprising;

an emitter configured to transmit light;

a detector configured to receive the transmitted light via a light path; and

an accelerometer configured to measure a change in motion that corresponds to a change in distance between the detector and the emitter along the light path; and

a pulse oximetry monitor configured to be coupled to the sensor, wherein the pulse oximetry monitor comprises a motion processor configured to receive measurements relating to the change in distance between the detector and the emitter from the accelerometer and to calculate an attenuation factor related to the measurements from the accelerometer.

2. The pulse oximetry system, as set forth in claim 1, wherein the attenuation factor is calculated based on an equation related to a model distance between the emitter and the detector, an expectation model of photon behavior between the emitter and the detector, and the measurements from the accelerometer to quantify attenuation of the transmitted light due to motion in the sensor assembly.

3. The pulse oximetry system, as set forth in claim 1, comprising a look-up table configured to store a motion measurement corresponding to the attenuation factor, wherein the attenuation factor is calculated based on a comparison between the measurements from the accelerometer and the motion measurement to quantify attenuation of the transmitted light due to motion in the sensor assembly.

4. The pulse oximetry system, as set forth in claim 1, comprising a processor configured to utilize the attenuation factor to calculate a physiological parameter.

5. The pulse oximetry system, as set forth in claim 4, comprising a display configured to display a representation of the physiological parameter.

6. A method comprising:

detecting motion of a physiological sensor via an accelerometer;

transmitting signals indicative of the motion of the physiological sensor to a monitor; and

calculating an attenuation factor in the monitor based on the transmitted signals.

7. The method, as set forth in claim 6, wherein calculating the attenuation factor comprises utilizing an equation related to a model distance between an emitter and a detector in the physiological sensor, an expectation model of photon behavior in the physiological sensor, and the transmitted signals to calculate the attenuation factor.

8. The method, as set forth in claim 6, wherein calculating the attenuation factor comprises utilizing a look-up table configured to store a motion measurement corresponding to the attenuation factor, wherein the attenuation factor is calculated based on a comparison between the transmitted signals and the motion measurement.

9. The method, as set forth in claim 6, comprising calculating a physiological parameter based on the attenuation factor.

10. The method, as set forth in claim 6, wherein detecting motion of a physiological sensor comprises measuring movement of the physiological sensor via an accelerometer.

11. The method, as set forth in claim 9, comprising displaying the calculating a physiological parameter on a display.