Abbott Laboratories Corporation

Gamal-Eddin Khalil

Martin P Gouterman

Edmond Green

Gerald G Vurek

Jeffrey B Yim

Roger J Pihl

Bradley D Huss

David P Brown

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.

Hemometrix temperature compensation

A CO.sub.2 /O.sub.2 or pH/O.sub.2 gas sensor comprising a single optical fiber and a method for making the same. The optical fiber carries light signals at different wavelengths for monitoring either CO.sub.2 concentration or pH level, in combination with O.sub.2 concentration. Attached to the distal end of the fiber-optic probe is a cylindrical pellet that has one surface covered by a light reflective material (gold foil) and the other surface attached adjacent to the distal end of the optical fiber. Depending on whether the sensor is to monitor either CO.sub.2 or pH, the pellet comprises either a CO.sub.2 analyte indicator molecule or a pH analyte indicator molecule covalently bonded to a polymer matrix material. Also adjacent to the distal end of the optical fiber is disposed a second polymer matrix material which is codissolved with an O.sub.2 analyte reactive indicator molecule. The second polymer matrix material is either interposed between the cylindrical pellet and the distal end of the optical fiber or surrounds the cylindrical pellet. If pH is being measured, the distal end of the optical fiber is coated with a hydrophilic material that is permeable to water. Conversely, if CO.sub.2 is being monitored, the distal end is coated with a hydrophobic material.

Apparatus for continuously monitoring a plurality of chemical analytes

Methods of and luminescent substances for measuring oxygen concentration of a test fluid. A test fluid is contacted with a plastic film containing a luminescent substance, the luminescent emission intensity of which is quenched in the presence of oxygen. The film is subjected to irradiation by light that is strongly absorbed by the luminescent substance, and a measure of the time dependence of luminescent emission intensity I(t) is obtained. Three modes of measuring quenching, and thus the oxygen concentration, from I(t) are described. These modes are insensitive to variation in plastic thickness, concentration of the luminescent substance, and take into account the non-exponential decay of the emission, thereby extending the range over which the film is sensitive. The luminescent substances include metallo derivatives of partially or fully fluorinated porphyrins which are photostable due to the fluorination of the porphyrin ring.

Method and sensor for measuring oxygen concentration

Method for measuring oxygen concentration

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Bellevue, WA, United States of America

Gamal-Eddin Khalil