Abstract:
Calibration apparatus and method for calibrating a movable pressure sensor (18) include the use of a stop device (98) to establish a reference position outside the sensing movement range of a first sensor. While in vitro, a reference pressure is established by applying pressure to the sensor (18) to move it against the stop surface (98) with a controllable pressure source (56). This reference pressure is stored (30). During use when the sensor is in an unknown position, such as when in vivo, the controllable pressure source applies pressure to move the sensor against the stop surface and the pressure required to do so is measured (62). The measured pressure is compared to the reference pressure to determine the unknown pressure and the system is then recalibrated. An optical system (42) may be used as a second sensor to determine the position of the first sensor. Inner (96) and outer (92) housings in which the first sensor and stop surface are mounted are moved in relation to each other and the optical sensor during assembly of the calibration system to accurately and independently calibrate the first and optical sensors.
Abstract:
The invention relates to a device for examining tissues with light, having means (11, 12, 31, 32; 1, 31, 22, 24) to radiate light bidirectionally through the tissue to be examined and means (51, 52, 71, 72, 81, 82) for detection, by means of which the proportions of the light transmitted through the tissue to be examined in both directions can be detected.
Abstract:
A specialized control wire (20) for use in the guidance of catheters (10) includes a stainless steel core covered at least in part with a low friction material. The deflector wire is resiliently biased into a linear orientation for the purposes of selectively urging the distal curved portion of the catheter into relaxed and unrelaxed positions.
Abstract:
A steerable catheter (10) comprises an elongated catheter body (12), a tip portion (14), first and second lumens (18, 20), a tightly wound coil (48), a puller wire (36), and a control handle.
Abstract:
This invention is an apparatus for determining pressure at one or a number of intermediate points along a catheter (10) inserted into a closed cavity. Fiberoptic cables (34) extend from the proximal end of the catheter (12a) to the intermediate points at which pressure measurements are taken as well as to the distal tip of the catheter (12d).
Abstract:
Method and apparatus for determining caloric expenditure of a subject. The apparatus includes a heat flow sensor (10) having an overlay (12) and/or conductive layer (14) for measuring the evaporative heat loss component, in addition to substantially total heat loss, for the subject.
Abstract:
An improved remote sensing tonometric catheter apparatus (20) and method for sampling of a fluid or gas property of interest in a hollow internal organ. The tonometric catheter (20) assists in early detection of the problems of stress ulceration and/or intestinal ischemia. The tonometric catheter (20) can be one or more sampling chambers (40) for introduction into an internal organ or area adjacent thereto. Preferably, the wall (36) of the sampling chamber (40) is freely permeable to the gas or fluid to be measured by the sensor (42), but is poorly permeable to other gases or fluids which may interfere with the sensor (42).
Abstract:
A roll formed, guide wire extension system (10) for connecting an extension wire (18) to a guide wire (14) is disclosed. The system comprises a connector or sleeve (30), a tubular outer body, a guide wire retention means, and extension wire retention means, a guide wire (14) and an extension wire (18). The sleeve (30) is produced by rolling a portion of a formable hollow tubular work piece upon an elongated projection with the projection being disposed at an angle with respect to the axis of the work piece. This process is repeated on the remaining part of the work piece to create external threads in the sleeve of opposite pitch. The roll formed external beads or dents in the sleeve create threads in the interior of the sleeve, the threads running in opposite directions and meeting at approximately the middle of the sleeve.
Abstract:
A system (10) for examination of a volume of biological tissue using visible or infra-red radiation includes a spectrophotometer (18), an optical medium (12) having selectable scattering and absorptive properties, and a processor (35) for determining a physiological property of the examined tissue. The spectrophotometer (18) includes a light source (21) for introducing radiation at an optical input port (19) and a detector (23) for detecting radiation that has migrated through a path from the input port (19) to an optical detection port (21). The biological tissue is positioned into a photon migration path inside the optical medium (12) to create a tissue-medium optical path. The optical medium (12) is adapted to limit substantially escape of photons from the tissue. The processor (35) determines tissue properties based on the detected optical property of the tissue-medium optical path and the selectable properties of the optical medium (12).