Medical service employing multiple DC accelerometers for patient activity and posture sensing and method

  • US 5,593,431 A
  • Filed: 03/30/1995
  • Issued: 01/14/1997
  • Est. Priority Date: 03/30/1995
  • Status: Expired due to Term
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First Claim
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1. A method of determining the physical posture of a patient'"'"'s body, having a superior-inferior body axis, an anterior-posterior body axis and a lateral-medial body axis, in relation to earth'"'"'s gravitational field comprising the steps of:

  • implanting a multi-axis, solid state sensor, comprising first and second DC accelerometers having first and second sensitive axes, respectively, which respond to earth'"'"'s gravitational field to provide first and second respective DC accelerometer signals of a magnitude and polarity dependent on the degree of alignment therewith, in the patient'"'"'s body so that said first and second sensitive axes are generally aligned with a respective first and second one of said superior-inferior, anterior-posterior or lateral-medial body axes;

    defining a first characteristic magnitude and polarity of said first and second DC accelerometer signals on alignment of the sensitive axes of said first and second DC accelerometers with earth'"'"'s gravitational field, a second characteristic magnitude and polarity of said first and second DC accelerometer signals on alignment against earth'"'"'s gravitational field, and a third characteristic magnitude and polarity of said first and second DC accelerometer signals on alignment normal to earth'"'"'s gravitational field;

    deriving first and second DC accelerometer signals from said first and second DC accelerometers as the patient assumes various body positions moving said first or second sensitive axes generally into alignment with earth'"'"'s gravitational field; and

    determining the body posture of the patient through comparison of the magnitudes and polarities of said derived first and second DC accelerometer signals with the magnitudes and polarities of said first, second and third characteristic magnitudes and polarities.

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