Liquid purification or separation – Processes – Separating
Reexamination Certificate
2000-08-14
2003-02-11
Reifsnyder, David A. (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S787000, C210S788000, C604S005010, C095S156000, C095S216000, C095S261000, C095S271000, C055S459100
Reexamination Certificate
active
06517732
ABSTRACT:
The present invention relates to a process and an apparatus for removing air from air-conditioning blood in accordance with the independent claims.
The invention relates, in particular, to the removal of air from a flowing stream of blood which is drawn off from a patient, for instance from a wound or place of operation, or from a blood-container of a blood-donor device.
Upon the drawing off of blood, for instance from a patient during an operation, air is frequently also drawn in from the environment. The air mixes with the blood and leads to damage to the components of the blood. In this way, treatment and reuse of the blood is made difficult.
In actual practice today, blood is drawn off from the operating wound of a patient by systems which consist of a cannula, a conveyor system in the form of a roller pump or a vacuum pump, a blood recirculation system, and connecting lines. These known systems extensively traumatize (damage) the blood.
The reasons for the traumatizing of the blood by the known systems are, among others, the following:
1. The active drawing off of blood from the operating region of a patient results in an intense mixing of the liquid phase (blood) with the gaseous phase (air). This mixing takes place not only at and in the suction cannula but also in the connecting lines, and it constitutes the main factor for the traumatizing of the blood.
2. In order to achieve an effective drawing-off of the blood, the known systems require a relatively high vacuum, which causes additional damage to the components of the blood.
More recent systems for the drawing off of blood are therefore developed in such a manner that they can separate the gaseous phase from the liquid phase so as to limit the damage done to the blood. The known systems are, however, bulky, large, heavy, difficult to operate, and expensive to manufacture. One such system is known, for instance, from U.S. Pat. No. 4,388,922.
The object of the invention is to create a blood-air separation system which has a less traumatic effect on blood and with which even micro-small air bubbles can be removed from a flowing stream of blood.
The invention is of particular advantage in operations with heart-lung machines, liver transplants, many other operations in body cavities and, in general, in the case of blood donations with a blood oxygenator.
Furthermore, the system in accordance with the invention is to be so developed that air present in the blood drawn off can be removed from the blood shortly behind the place where the blood is drawn off, and in particular close to the patient. The system is to be of low cost and easy to use. The system of the invention is to make the following possible:
1. Maximum separation of the gaseous phase (air), even if it consists of small air bubbles of a diameter of only a few &mgr;m, from the liquid phase (blood), preferably immediately and directly at or close to the place where the blood is drawn off;
2. A reduction in the vacuum necessary for the drawing off. This object is achieved in accordance with the invention by the independent claims.
In accordance with the invention, the blood is placed in an eddying in a cyclone, so that the heavy components of the blood-air mixture are forced radially outward by centrifugal force while the physically lighter components and thus, in particular, the air are forced into the radial center of the cyclone eddy stream. By separate drawing off of the radially outwardly forced liquid phase and of the gaseous phase forming radially within it, the gaseous phase is separated from the liquid phase.
In the present specification and the drawings, only embodiments with one cyclone are shown. However, it is clear to the person skilled in the art that several cyclones in parallel or in series can also be used. The following description of a cyclone is therefore representative of embodiments having several cyclones used in parallel or in series.
In one preferred embodiment of the invention, the cyclone is arranged in a small handle part of a blood-suction cannula. This has the advantage that the air is separated from the blood directly behind the place of removal of the blood and that the cyclone is in a position which is favorable from a standpoint of weight. The cyclone can be integrated into the blood-suction cannula or be arranged at the downstream end of the blood-suction cannula. The outer wall of the cannula and/or of the handle part preferably at the same time forms the outer wall of the cyclone.
Further features of the invention are set forth in the dependent claims.
REFERENCES:
patent: 2 063 108 (1981-06-01), None
Brockoff Alexander
Plechinger Hans
Beck & Tysver P.L.L.C.
Convergenza AG
Reifsnyder David A.
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