Abstract: A fiber-optic probe for measuring the partial pressure of CO.sub.2 in a medium includes a single optical fiber having a distal end; a mirror; a hydrolyzed dye/gel polymer, the dye being in contact with a bicarbonate solution; a solution permeable membrane covering the fiber distal end, hydrogel and mirror; and a gas-permeable membrane covering the solution permeable membrane.

Abstract: Heat is removed from the blood flow by heat exchange rather than cold-liquid injection; resulting temperature changes are monitored. Flow rate is found from monitored temperature and known parameters related to the amount of heat removed. Preferably heat is removed by pumping cold liquid into a sealed balloon or sheath along a catheter, which is in the blood stream. The balloon acts as a heat exchanger; its design optimizes that function. Temperature can be monitored by a thermistor or other sensor closer to the tip of the same catheter. Alternatively it appears possible to use blood-temperature measurements taken just outside the balloon, or even within the balloon, if the system is calibrated to account for the relation between the blood flow rate and the heat lost from balloon to blood.

Abstract: A resilient valve core, biased against its seat in a molded body, controls large flow volumes for flushing. A small resilient tube embedded in the core bypasses the valve to provide smaller flow volumes for IV-fluid drip. For flushing, the core is deformed, rather than bodily moved, relative to the body. A fluid-flow channel is recessed along one side of the valve cavity, and the valve seat forms a short barrier across this channel. The core is a T-shaped unitary member; the center of the "upper" surface of the T crossbar is biased against the seat, and the extrema of the crossbar are hermetically sealed against the valve body, while the stem of the T extends outward from the body. A user squeezes a cowling mounted outside the body to start and control flushing. The cowling itself deforms to pull the stem of the T outward, deforming the T and separating the middle of its crossbar portion from the valve seat. A user can elect to grasp and pull the stem directly.

Abstract: A damping device for use in conjunction with a circulatory pressure measuring system to attenuate resonant pressure waves therein includes a series connector for connection to the pressure measuring system. An integrally connected parallel portion includes a capillary tube fluid resistance element in communication with the series connector. A flexible membrane isolates the capillary tube from a fixed volume gas chamber located adjacent the flexible membrane.

Abstract: An optical fiber carries a light beam through a cardiovascular catheter and projects the beam into the patient's bloodstream. Two other fibers, spaced in a very carefully controlled configuration from the first, receive light scattered by corpuscles (and blood-vessel walls) and transmit this reflected light back through the catheter to respective detectors outside the patient's body. If preferred, two input fibers and a single output fiber--or other techniques for providing differential geometry--may be used instead. Electronic instrumentation finds the ratio of the two light fluxes, thus cancelling out unknown variables such as input light intensity and optical--connector attenuation. The known differential geometry between the two light paths permits calibration of the ratio measurement in terms of corpuscular concentration--i.e., hematocrit. Light at only one wavelength suffices for the measurement. Advanced forms of the invention correct for proximity of blood-vessel walls.

Abstract: An optoelectronic system for measuring at least one property of an environment includes a first light source for generating light at a first wavelength, first feedback means coupled to the first light source for maintaining the light from the first light source at a substantially constant level, a second light source for generating light at a second wavelength, second feedback means coupled to the second light source for maintaining the light from the second light source at a substantially constant level, a sensor to be placed in an environment, the sensor being responsive to a change in a property of an environment, the sensor generating first and second optical output signals representing a change in the light from the first and second light sources, respectively, due to a property of the environment, an optical waveguide for transmitting light from the first and second light sources to the sensor, a detector for detecting the first and second optical output signals, an optical waveguide for transmitting th

Abstract: A multiple sensor which can be readily inserted into, and removed from a radial arterial cannula for use in continuous in vivo patent monitoring includes a plurality of individual sensors, each sensor including a sensing element disposed on an optical waveguide, the sensors being bonded together by an adhesive without covering the sensing elements.

Abstract: A device is described for sensing oxygen, particularly for use in medical applications. The device includes an optical waveguide and an oxygen sensing medium disposed on the waveguide. The sensing medium fluoresces in response to light from a light source such that the intensity of fluorescence is dependent on the partial pressure of oxygen in the environment. The sensing medium includes an oxygen sensitive fluorescent dye in a matrix consisting of a plasticized polymer.

Abstract: The catheter tip fits into a cavity in the boot and is held gently (in the longitudinal direction) by a detent formed within the cavity. A calibration substance faces the tip in a mechanically and optically standardized calibration relationship, to reflect light from within the catheter back into the catheter. The calibration substance is held in constant, precise contact with the tip--but passively, not by springs or other longitudinally forcible devices but by close fit between the tip and the precision-molded internal surfaces of the cavity. In the lateral direction the boot may tightly grip the tip, at a point where the optic fibers are protected against such force. To provide a reflection standard for calibration, the calibration substance is of standardized character and quality: it is preferably a homogeneous suspension of reflecting particles in translucent or transparent polymer.

Abstract: Cardiac output, blood oxygen saturation, and oxygen consumption are measured using only two lumens of a catheter that has no interlumen crossover. Therefore this construction avoids costly techniques for modifying the catheter, as well as leakage risk at crossover points. Cardiac output is measured by thermodilution, and venous blood oxygen by optical scattering measurements through optic fibers; oxygen consumption is then claculable from the cardiac output and venous oxygen saturation--and independently measured arterial saturation. Cold-bolus injection uses on lumen. The thermal-sensor leads (electrical or otherwise) and optic fibers share the other lumen, through which they are drawn together: this method of installation effects yet a further economy by saving an expensive labor step, and tends to prevent the leads and fibers from damaging one another.

Abstract: A multiple sensor which can be readily inserted into, and removed from a radial arterial cannula for use in continuous in vivo patent monitoring includes a plurality of individual sensors, each sensor including a sensing element disposed on an optical waveguide, the sensors being bonded together by an adhesive without covering the sensing elements.