Abstract: A system (10) for in vivo measuring chemical and physical parameters of a patient's blood includes a probe (12), a sensing system (14), and flush interference warning devices (20). The system measures pH, pCO.sub.2, and temperature values, and determines a base excess value using the measured pH and pCO.sub.2. The time rate of change of the base excess value is also determined, as is the time rate of change of temperature. The warning devices are activated, indicating that the measured parameters are likely affected by the presence of flush solution flowing past the probe, when either: (a) the base excess value is less than a predefined threshold base excess; (b) the absolute value of the time rate of change of the base excess value is greater than a predefined threshold time rate of change of base excess; or, (c) the absolute value of the time rate of change of temperature is greater than a predefined threshold time rate of change of temperature.

Abstract: A method and system for controlling the intervals during which light signals are sampled in a fiber-optic sensing system compensates for signal artifacts that are caused by movement of the fiber-optic waveguide during the sampling. The method and system sample the light signals at intervals that are shorter than the intervals during which displacement of the optical waveguide occurs in normal use. The short-sampling intervals result in the individual sampling of different wavelengths of light being exposed to the same changes in transmission characteristics of the optical waveguide which causes signal artifacts. Accordingly, when subsequent processing of the collected signals occurs, the effects of the signal artifacts are compensated for.

Abstract: Fiber optic sensors suitable for monitoring physiological analyte concentrations are described. The sensors include analyte permeable matrices disposed in a light path defined by the axial core at one end of an optical fiber segment. The matrix contains an indicator molecule covalently linked to a polymer or admixed with the polymer. The indicator molecule may be an absorptive molecule or a luminescent molecule. pH, PCO.sub.2, and PO.sub.2 sensors are described and may be disposed together in substantially coterminal arrangement to make a multivariable probe.

Abstract: 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.

Abstract: A bundle of fiber-optic sensors that resist breakage, for use in measuring pH, CO.sub.2, and O.sub.2 concentration, and a method of making the same. Three otpical fibers are enclosed in a common polyimide sheath and extend parallel to one another toward a distal end of the sensor, where they are bonded together in a mutually supportive array. At the distal end of one of these optical fibers is disposed a pellet comprising a CO.sub.2 analyte indicator molecule codissolved within a polymer matrix. A thin reflective surface of gold foil is provided on the pellet such that incident light transmitted through the optical fiber and polymer matrix is reflected back into the optical fiber. The CO.sub.2 polymer matrix absorbs light of a given wavelength to an extent dependent upon the level of CO.sub.2 present.

Abstract: Methods of monitoring analyte concentration in fluids using fiber optic sensors that include analyte permeable matrices disposed in a light path at one end of an optical fiber waveguide. The analyte permeable matrix includes an indicator molecular capable of responding to the analyte in an optically detectable manner. The absorbance or emission from the analyte permeable matrix after irradiation is used to determine the concentration of the analyte in the fluid as a function of the measured absorbance or emission. Methods for manufacturing fiber optic sensors useful in a method of monitoring analyte concentration in a fluid include casting a polymer film that includes an indicator molecule capable of responding to the analyte in an optically detectable manner. Disks or pellets are punched from the film and applied to the end of an optical fiber waveguide.

Abstract: Fiber-optic sensors suitable for monitoring physiological analyte concentration. An analyte-permeable matrix is disposed in the light path defined by the axial core at one end of an optical fiber segment. The matrix contains an indicator molecule covalently linked to a polymer, preferably methyl methacrylate/methacrylamidopropyltrimethylammonium chloride, N-vinylpyrrolidone/p-aminostyrene, methyl methacrylate/hydroxymethyl methacrylate, methyl methacrylate/N-vinylpyrrolidone, or methyl methacrylate/acrylic acid. In representative embodiments, the polymer is approximately 94:6 mole/mole percent of either methyl methacrylate/methacrylamidopropyltrimethylammonium chloride or N-vinylpyrrolidone/p-aminostyrene copolymer. Drift-free performance is obtained with such sensors having analyte-permeable matrices of significantly less than about 70 microns in thickness.