The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 08, 1994
Filed:
Dec. 30, 1991
Gamal-Eddin Khalil, Bellevue, WA (US);
David P Brown, Edmonds, WA (US);
Abbot Laboratories, Abbott Park, IL (US);
Abstract
A method for converting a value for the partial pressure of oxygen (pO.sub.2) in blood at a measurement temperature to a corresponding value at a reference temperature (37.degree. C.). A value for pO.sub.2 is determined by measurements made in a patient's blood stream using a phosphorescent compound that is sensitive to the concentration of oxygen. The phosphorescent compound is illuminated with a short pulse of light, causing it to produce a phosphorescent emission having a rate of decay that varies as the function of the partial pressure of oxygen in the blood surrounding the phosphorescent compound. A detector produces an electrical signal corresponding to the intensity of the phosphorescent emission, and the electrical signal is converted to a corresponding digital value for input to a microcomputer. Also supplied to the microcomputer in digital form is a signal indicative of the temperature at the measurement site where the phosphorescent compound is disposed. The microcomputer determines the phosphorescent decay rate and from that value, determines the pO.sub.2 at the measurement site for the temperature at which the measurement was made. An initial estimate of a corresponding value for pO.sub.2 at the reference temperature is made as a function of the measurement temperature and the pO.sub.2 at that temperature. A more accurate estimate of pO.sub.2 at the reference temperature is iteratively determined by successively evaluating an expression that is a function of the initial measurement and a previous more accurate estimate. If the measurement temperature is less than the reference temperature, the current more accurate estimate is replaced by the average of the previous two estimates. A final more accurate estimate representing the value for pO.sub.2 at the reference temperature is then displayed.