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Hemometrix temperature compensation

  • US 5,284,139 A
  • Filed: 12/30/1991
  • Issued: 02/08/1994
  • Est. Priority Date: 12/30/1991
  • Status: Expired due to Fees
First Claim
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1. A method for determining a partial pressure of oxygen of blood at a predefined reference temperature of blood during an in vivo blood gas measurement, comprising the steps of:

  • (a) measuring in vivo a partial pressure of oxygen of blood at an arbitrary temperature that is substantially different than the reference temperature of blood, as a function of a physical parameter that changes to indicate the partial pressure of oxygen of blood at a measurement site, said step of measuring including the steps of;

    (i) producing a first signal indicative of the partial pressure of oxygen of blood, in response to changes in the physical parameter;

    (ii) producing a second signal indicative of the arbitrary temperature of blood at the measurement site; and

    (iii) processing the first signal to determine the partial pressure of oxygen of blood at the arbitrary temperature;

    (b) determining an estimate of a partial pressure of oxygen of blood at the predefined reference temperature of blood as a function of the partial pressure of oxygen of blood at the arbitrary temperature of blood, and of the second signal;

    (c) determining a more accurate estimate of the partial pressure of oxygen of blood at the predefined reference temperature as a function of;

    (i) the partial pressure of oxygen of blood at the arbitrary temperature of blood;

    (ii) the second signal; and

    (iii) the estimate of the partial pressure of oxygen of blood at the predefined reference temperature; and

    (d) iteratively repeating step (c), each iteration using said more accurate estimate of the partial of oxygen of blood from a previous iteration as a value for said estimate in (c)(iii), until a predefined number of such iterations have been completed, a more accurate estimate that results from a last of such iterations approximating the partial pressure of oxygen of blood at the predefined reference temperature corresponding to the measurement of the partial pressure of oxygen of blood made at the arbitrary temperature of blood.

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