Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
1999-12-06
2001-03-27
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
C356S410000, C422S068100
Reexamination Certificate
active
06208880
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention broadly relates to a device for measuring one or more parameters of blood, and is especially suitable for use during surgical procedures.
2. Description of the Related Art
Various characteristics or parameters of blood are often monitored in real time during certain surgical procedures. For example, during open heart surgery the surgeon and other members of the surgical team often monitor the pH of the patient's blood as well as the concentration of certain blood gases such as carbon dioxide and oxygen. In many instances, the parameters of the patient's blood are monitored not only as the surgery is progressing, but also in the time period before and after the surgical procedure. In addition, the potassium ion is used to stop the heart during open heart surgery and as a consequence the potassium ion must be monitored periodically during the procedure.
Measurement of blood parameters is often accomplished using an extracorporeal blood circuit having lengths of flexible tubing with passageways that are in fluid communication with the vascular system of the patient. In many extracorporeal blood circuits, one or more sensors that are useful for determining blood parameters are placed adjacent the passageway and are connected to a processing unit. The processing unit is typically connected to a display device such as a monitor so that the surgical team can review the parameters of interest when desired. Optionally, the processing unit is connected to a recording device such as a printer to provide a log of the parameters over a period of time.
Optical sensors are often used for sensing blood parameters in real time. For example, U.S. Pat. No. Re. 31,879 to Lubbers et al. and U.S. Pat. No. 5,403,746 to Bentsen et al. describe fluorescent sensors that respond to light in accordance to the partial pressure of oxygen, the partial pressure of carbon dioxide and the pH of blood. U.S. Pat. No. 5,162,525 to Masilamani et al. and U.S. Pat. No. 5,474,743 to Trend et al. Describe fluorescent sensors that respond to the potassium ion or other ions. Sensors that function on the principles of light absorbance are described, for example, in U.S. Pat. No. 4,041,932 to Fostick.
Optical sensors for measuring blood parameters are often optically coupled to a remote measuring device that includes a source of light for directing light to the sensors, apparatus for analyzing the light returned from the sensors and a monitor for providing a visual display of the measurement. In many systems, a bundle of optical fibers extends from the remote device to a transmission block or retainer, and a releasable coupling is provided to detachably connect the retainer or block to a cell or housing that supports the sensors. Such a system is shown, for example, in U.S. Pat. No. 4,989,606 to Gehrich et al. Unfortunately, the bundle of optical fibers in those systems is somewhat costly and may be damaged unless protected.
Extracorporeal blood circuits having sensors for determining blood parameters may be arranged in various manners, and the manner selected for use in a particular instance often depends upon the preferences of the surgical team. In some cases, the sensors are mounted in a housing located along a length of relatively small-diameter tubing that is connected at only one end to the patient's blood supply, and a device such as a syringe is used to draw a sample of blood past the sensors. Examples of such circuits are described in the aforementioned U.S. Pat. No. 4,989,606 to Gehrich et al.
Another type of extracorporeal blood circuit has sensors located along tubing that is part of an arterial or a venous passageway connected to an oxygenator. The sensors in this type of circuit are often connected to an element known as a flow-through cell that has fitting on opposite sides for coupling to the circuit tubing. Flow-through cells are described, for example, in U.S. Pat. No. 4,640,820 to Cooper.
While the systems mentioned above are generally satisfactory, there is a continuing need in the art to improve the convenience, accuracy and efficiency of conventional blood gas measuring devices. In addition, a system that is relatively compact and unobtrusive would be a particular advantage during many medical procedures.
SUMMARY OF THE INVENTION
The present invention in one aspect relates to a system for measuring one or more parameters of blood. The system includes a cassette having a chamber for receiving a quantity of blood and at least one light sensor. The system also includes a device having a housing with a coupling for releasable connection to the cassette. The device includes at least one light source that is fixed to the housing for directing light toward the at least one sensor. The device also includes at least one light detector fixed to the housing for detecting light from the at least one sensor. A signal converter is fixed to the housing and is connected to the at least one light detector. The signal converter provides a digital output signal that varies in response to the quantity of light detected by the at least one light detector.
Another aspect of the present invention is related to a device for measuring one or more parameters of blood. The device includes a housing having a coupling for releasable connection to a blood parameter measurement cassette having a sensor, a light source, and a first set of optical fibers that is optically coupled to the light source. The device also includes a first light detector and a second light detector, an optical reference material, and a second set of optical fibers optically coupled to the first light detector and the second light detector. The first set includes a first group of optical fibers to direct light from the light source to the sensor and a second group of optical fibers to direct light from the light source to the reference material. The second set includes a first group of optical fibers to direct light from the sensor to the first light detector and a second group of optical fibers to direct light from the reference material to the second light detector. A signal converter is connected to the first light detector and the second light detector and provides at least one output signal that varies in response to the quantity of light detected by the first light detector and the second light detector. The light source, the first light detector, the second light detector, the first set of optical fibers, the second set of optical fibers, the reference material and the signal converter are all contained within the housing.
The present invention also concerns a device for measuring one or more parameters of blood. The device includes a housing having a coupling for releasable connection to a blood parameter measurement cassette, at least one light source and a first plurality of optical fibers optically coupled to the at least one light source and extending toward the coupling for directing light toward the cassette. The first plurality of optical fibers has a certain cross-sectional area adjacent the coupling. The device also includes at least one light detector and a second plurality of optical fibers optically coupled to the at least one light detector and extending toward the coupling for receiving light from the cassette. The second plurality of optical fibers has a cross-sectional area adjacent the coupling that is in the range of about two to about four times the certain cross-sectional area of the first plurality.
In yet another aspect, the present invention is directed toward a system for measuring one or more parameters of blood. The system includes a device having an elongated housing with a coupling, at least one light source fixed to the housing and at least one light detector fixed to the housing. The system also includes a cassette having wall sections defining a chamber for receiving a quantity of blood. The cassette includes a coupling for releasably connecting the cassette to the device. The cassette includes at least one sensor connected to the wal
Abul-Haj N. Alan
Abul-Haj Roxanne E.
Bentsen James G.
Hacker Thomas G.
Heinemann Stanley O.
Burns Doane , Swecker, Mathis LLP
Terumo Cardiovascular Systems Corporation
Winakur Eric F.
LandOfFree
Blood parameter measurement device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Blood parameter measurement device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Blood parameter measurement device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2487037