Edwards Lifesciences Corporation

Baxter International Inc.

Other

Thermometrics

Michael J. Higgins

Michael J Higgins

Todd N Fjield

Stacy Faught

Mark Gordon

Clifford Currier

Dean West

James R Petisce

Manouchehr A Miraki

Robert A Pecor

Donald E Bobo, Jr

Erik E Bulman

Mark A Konno

Dawood Parker

Todd Abraham

Charles R Mooney

James Mottola

Steven Backer

Arthur Goldberg

Harold Broitman

Luong N Phan

Kristie Trinh

Gary R Willoughby

Luong Ngoc Phan

Jennifer Wilbur

Apparatus and methods are described for preparing, maintaining, and stabilizing sensors. The apparatus and methods for preparing sensors for use are utilized in advance of the sensor being removed from a sealed, sterilized package. The apparatus include packaging materials having electrical circuits capable of stabilizing a sensor to prepare the sensor for use. The methods for preparing a sensor for use includes methods of providing a solution to a sterilized packaging that contains a sensor connected to a sensor activating circuit, activating the circuit, and allowing the sensor to stabilize. These methods can be performed without compromising the packaging. The apparatus for stabilizing a sensor that is in use include a circuit connectable to the sensor that provides a signal to the sensor that prevents the sensor from becoming destabilized when disconnected from a monitoring device.

Preparation and maintenance of sensors

Methods for measuring the total hemoglobin of whole blood include measuring reflective light at multiple wavelengths within the visible spectrum, calculating light absorbance at each of the multiple wavelengths, performing a comparison in a change in like absorbance between the multiple wavelengths, and/or relating the comparison to total hemoglobin. A system for measuring total hemoglobin of whole blood may include at least one light source, a catheter, optical fibers, at least one photodetector, data processing circuitry, and/or a display unit.

Continuous spectroscopic measurement of total hemoglobin

Methods and systems for preparation of calibrant infusion fluid sources are disclosed. In one embodiment, a precise volume of glucose is injected into a saline-solution filled calibrant infusion fluid source proximate in time to conducting a calibration procedure. The glucose concentration in the calibrant infusion fluid source is subsequently calculated based on the measured weight of the saline-solution, as determined prior to glucose injection, and the volume of glucose injected. This method provides a highly accurate and convenient manner for use in a hospital environment, for example, with an intravenous blood glucose sensor system. In another embodiment, a premixed calibrant infusion fluid source is provided that includes saline solution and a predetermined concentration of glucose. In such embodiments, shelf life problems related to water evaporation are mitigated by hermetically covering or otherwise hermetically containing the calibrant infusion fluid source up until the point of use.

Calibrant infusion fluid source preparation

A method for compensating for a temperature-related error in an electrochemical sensor without using separate sources of temperature measurement by measuring sensor current, temporarily lowering sensor voltage to a first level below a reaction-sustaining threshold, measuring a first offset current, adjusting sensor voltage to a second level below the threshold, measuring a second offset current, calculating a difference between the offset currents, deriving a temperature compensation value from the difference based on empirical data, and adding the value to the measured sensor current. A computer system may execute the method as an algorithm stored in memory, provide automatic control of the sensor, and provide continuous display of corrected output values.

Monitoring and compensating for temperature-related error in an electrochemical sensor

Oxygenation of a subject's blood is determined by sensing an absorption spectrum of light directed either invasively or non-invasively into the blood, and then calculating an oxygenation value by evaluating a cost function of the remitted spectrum relative to at least two pre-determined reference absorption spectra representing different, known levels of blood oxygenation. The source of light preferably uses stable, long-life, white LEDs, in which case white-balancing of the remitted spectrum can be accomplished by pre-determining and storing the spectrum of the LEDs, one time for all, and then adjusting the remitted spectrum accordingly to compensate for deviations of the LED spectrum from the constant ideal.

Measurement of blood oxygen saturation

A multiple lumen catheter having a soft, tapered multiple lumen distal tip for insertion into a body vessel. One of the lumens is sized to pass over a guidewire such that the catheter can be inserted into the body vessel using the Seldinger technique. At least one medical implement lumen is used for placement or positioning of a biomedical sensor or other medical implement. For example, at least one optical fiber passing through the medical implement lumen may transmit and receive light at the distal tip for measuring oxygen saturation of the blood. The catheter may have a cylindrical catheter body to which the soft distal tip attaches. The soft tip reduces the possibility of vessel or tissue puncture and abrasion. The tip is constructed of a soft plastic or pliable material that yields easily when force is applied. For example, the tip may be made of a softer material than the catheter body, or if made of the same material, the tip can be configured with thinner walls or a higher air-to-material ratio cross-section. Various geometrical configurations and combinations of materials can be used to decrease the flexible resistance of the tip to an applied load. One particular useful application for the catheter of the present invention is as a central venous catheter equipped with fibers for measuring oximetry. The fibers extend to the distal end of the tip and are preferably secured therein with minimal adhesive so as to limit the stiffness added to the tip. One particular useful construction is to secure the fibers within the medical implement lumen using adhesive only along a length of between about 0.5&#x2013;3.5 mm.

Multiple lumen catheter having a soft tip

A multiple lumen catheter having a soft, tapered multiple lumen distal tip for insertion into a body vessel. One of the lumens is sized to pass over a guidewire such that the catheter can be inserted into the body vessel using the Seldinger technique. At least one medical implement lumen is used for placement or positioning of a biomedical sensor or other medical implement. For example, at least one optical fiber passing through the medical implement lumen may transmit and receive light at the distal tip for measuring oxygen saturation of the blood. The catheter may have a cylindrical catheter body to which the soft distal tip attaches. The soft tip reduces the possibility of vessel or tissue puncture and abrasion. The tip is constructed of a soft plastic or pliable material that yields easily when force is applied. For example, the tip may be made of a softer material than the catheter body, or if made of the same material, the tip can be configured with thinner walls or a higher air-to-material ratio cross-section. Various geometrical configurations and combinations of materials can be used to decrease the resistance of the tip to an applied load. One particular useful application for the catheter of the present invention is as a central venous catheter equipped with fibers for measuring oximetry. The fibers extend to the distal end of the tip and are preferably secured therein with minimal adhesive so as to limit the stiffness added to the tip. One particular useful construction is to secure the fibers within the medical implement lumen using adhesive only along a length of between about 0.5&#x2013;3.5 mm.

Central venous catheter having a soft tip and fiber optics

A multiple lumen access device for use in providing a single entry port into the human body for selectively introducing medical implements therethrough and for providing simultaneous auxiliary access into the body. The multiple lumen access device includes a multi-lumen sheath which may have an outer tube and structure defining a device lumen located therein. The inner structure may be an inner wall or inner tube. The outer tube and inner structure are located so as to define at least one auxiliary lumen. Some embodiments include flexible inner walls which can be flexed between relaxed and expanded/contracted positions wherein the relative cross-sectional areas of the device lumen and auxiliary lumens are varied. The access device further includes a valve which provides sealing of the device lumen. The valve may be provided in a lumen junction housing or separate from the housing either permanently or removably connected with the device lumen. Alternatively, a multi-lumen sheath may be passed through a valve leading to a conventional introducer. The valve may also be molded separately as a rigid insert and retained in a cavity formed in a flexible junction housing. In other embodiments, the multiple lumen access device is formed by introduction of the elongated implement coaxially within a tubular single lumen sheath.

Multiple lumen access device

A system for measuring biological functions of a patient, such as cardiac output, filters noise from a signal provided by a thermistor catheter inserted into the body of the patient. A signal-conditioning cable is disposed between the catheter and an instrument which processes the signal to measure cardiac output. The cable includes circuitry which forms, in combination with a thermistor of the catheter, a low-pass filter for attenuating thermal and high-frequency noise from the signal provided to the instrument. The instrument can more accurately measure cardiac output with the filtered signal than with an unfiltered signal. Although the circuitry which forms the low-pass filter may be combined with the catheter or the instrument, it is preferred to dispose the circuitry in a separate cable to reduce manufacturing costs of the catheter and retrofitting costs of existing instruments.

Methods and apparatus for reducing noise in systems using thermistor

A biomedical pressure sensor having a pressure sensing diaphragm is provided with a distensible membrane overlying the diaphragm, and the diaphragm is provided with one or more holes. During normal operation, externally applied pressure forces the membrane against the diaphragm so that the membrane and diaphragm deform under pressure as a unit and transmit pressure-applied forces to a force transducer within the probe housing. When a reference pressure exceeding the externally applied pressure is supplied within the probe housing, such reference pressure passes through the hole in the diaphragm and forces the membrane away from the diaphragm, thereby isolating the diaphragm from the externally applied pressure and bringing the diaphragm to a zero-differential pressure condition. Use of a hole in the diaphragm permits an extremely compact construction.

Pressure sensing probe with calibration capability

A calibration device is provided for in vitro calibration of a light guide. The calibration device has a surface defining a cavity having an open end and a closed end opposite the open end. The opening is sized to receive the end portion of a light guide and a stop is provided near the closed end to prevent the light guide from contacting the inner surface of the closed end and to define an air gap between the end face of the light guide and the inner surface of the closed end. The inner surface of the closed end is flat and perpendicular to the longitudinal axis of the light guide. The light guide directs light from the end face of the light guide across the gap and against the flat surface. The calibration device is formed of a suitable material, such as polyethylene, with a plurality of light scattering particles and a plurality of light absorbing particles having neutral density filter properties uniformly distributed therein. Preferred light absorbing particles that have the properties of a neutral density filler are carbon black.

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Huntington Beach, CA, United States of America

Michael J Higgins