Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-07-02
2001-02-13
Kennedy, Sharon (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C422S068100
Reexamination Certificate
active
06186983
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a body fluid analysis system for extracorporeal body fluid analysis with a sensor arrangement. The present invention also relates to a method for flushing and single-point calibration of a sensor arrangement in a closed, body fluid analysis system.
2. Description of the Prior Art
In e.g. extracorporeal analysis of blood with known systems for continuous or semi-continuous blood analyses via a venous or arterial catheter, the heart or an external pump pumps the blood to a sensor outside the body. After the blood analysis, performed by the sensor, the blood is returned to the body when a flushing liquid is pumped in the opposite direction. After a large part of the blood has been pumped back to the patient, the sensor is flushed with additional flushing liquid to remove any residual blood. This flushing liquid can either be infused into the patient or collected in a special bag. When flushing has been concluded, the flushing liquid, which is then in contact with the sensor, is sometimes used for calibration.
Instability and a short operating life are the main disadvantages of these known systems for blood analysis.
The number of pumps and the number of bags/containers employed by these known systems are additional disadvantages.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a body fluid analysis system, and a method for flushing and single-pointy calibration of the sensor of such a system, wherein the aforementioned problems are avoided.
The above object is achieved in a body fluid analysis system according to the present invention having a container, holding at least one flushing liquid, and a first tube connected to the container at a first point and at a second point to form a closed system. The sensor is connected to the first tube, and to a second tube for connection to a patient. The body fluid analysis system also has a pump connected to the first tube between the first point and the sensor.
One advantage of the body fluid analysis system according to the present invention is that it can be realized at low cost. The system is also easy to operate. An additional advantage is that the system only needs one pump and one container. Moreover, the body fluid analysis system according to the present invention is stable and has a long operating life.
In an embodiment the body fluid analysis system can also include a valve, connected to the first tube between the second point and the sensor, the pump and valve being connected to the first tube on opposite sides of the sensor.
It is advantageous to operate the body fluid analysis system with higher-than-ambient pressure in the container.
In a further embodiment of the body fluid analysis system, the valve is arranged by the sensor and is also connected to the second tube.
The flow resistance in the two tubes can be optimized by the choice of appropriate tube diameters and/or chokes using the valve.
A filter arrangement for filtering out bacteria can be connected to the first tube between the pump and sensor.
The body fluid analysis system can also include an analysis unit, connected to the container, for monitoring contamination of the flushing liquid(s).
The analysis unit can be a spectral analysis unit or an absorption analysis unit.
The body fluid analysis system additionally can contain an indication arrangement, connected to the analysis unit, for indicating if contamination of the flushing liquid(s) exceeds a redetermined level.
A method according to the present invention for flushing and single-point calibration of a sensor in a closed, body fluid analysis system as described above has the following steps. Body fluid is pumped to the sensor. The body fluid is analyzed using the sensor. Flushing liquid is pumped from a container through the sensor in order to flush the sensor. Flushing liquid is collected in the container after the sensor is flushed.
The method additionally can include the following steps. A valve is closed at the same time as the pump pumps fluid toward the container so as to direct body fluid to the sensor. The valve is kept closed, and the pump is inactive while the sensor analyzes body fluid. The valve is still kept closed at the same time as the pump pumps fluid toward the sensor in order to return the body fluid to the body fluid source. The valve is opened while the pump pumps fluid toward the sensor in order to pump flushing liquid through the sensor.
The method additionally can include the step of filtering out bacteria either in the body fluid or flushing liquid.
The method additionally can include the step of, after the flushing stage, using the flushing liquid for single-point calibration of the sensor.
REFERENCES:
patent: 4608996 (1986-09-01), Brown
patent: 4786394 (1988-11-01), Enzer et al.
patent: 5057278 (1991-10-01), Maxwell et al.
patent: 5165406 (1992-11-01), Wong
patent: 5781284 (1998-07-01), Infante
Kennedy Sharon
Schiff & Hardin & Waite
Serke Catherine
Siemens Elema AB
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