Pumps – Processes
Patent
1995-06-01
1997-10-14
McAndrews, Jr., Roland
Pumps
Processes
4174231, 41742314, 415 1, F04B 1703, F04B 1500
Patent
active
056765266
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for eliminating air bubbles in a centrifugal pump which comprise an artificial heart-lung machine used to process liquid fluid which includes blood taken from a patient and then returning the processed blood and liquid fluid to the patient, during a procedure such as heart surgery.
BACKGROUND ART
In general, an artificial heart-lung machine which processes blood as it circulates the blood outside the body is designed to temporarily store in blood storage chamber 1 venous blood taken from a patient's vein via a blood drawing line, as shown in FIG. 3. In this design, the blood in this blood storage chamber 1 is relayed via a pump 2 to artificial lung 4 which has a heat exchanger 3. Blood which has undergone gas exchange at the artificial lung 4 is then returned to the patient's artery via a blood return line.
Roller pumps, which send out blood by squeezing the tube which forms the blood circulation path with a roller, and centrifugal pumps, which send out blood by means of centrifugal force, may be used as the pump 2 employed in this type of artificial heart-lung machine.
An explanation will now be made of the structure of the centrifugal pump using the figures. As shown in FIGS. 4 and 5, this centrifugal pump 11 is composed of a centrifugal pump main body 12 which sends out the blood which has been taken thereinto, and a driving portion 13 which drives this centrifugal pump main body 12.
Vessel 14 which forms centrifugal pump main body 12 has a centrifuge chamber 15, consisting of a conically shaped hollow portion, and a magnet chamber 16 which is sealed off from centrifuge chamber 15. A blood inlet 17 is formed to this vessel 14 lying along the axis thereof. Further, a blood outlet 18 is formed to the side of vessel 14 lying in the tangential direction of centrifuge chamber 15 at the side of vessel 14.
Further, a shaft 21 which is provided spanning between centrifuge chamber 15 and magnet chamber 16 is supported in a rotatable fashion inside vessel 14. A rotating body 23 which has a plurality of vanes 22,22 is affixed to the end of this shaft 21 which projects toward centrifugal chamber 15. Further, a circular magnet 24 is affixed to the end of shaft 21 which projects out toward the magnet chamber 16.
Further, drive portion 13, which is attached to centrifugal pump main body 12, supports centrifugal pump main body 12 in a state wherein its axis is horizontal and supports blood outlet 18 in a state wherein it is level above centrifugal pump main body 12 (see FIG. 5). A drive magnet 25 which is rotated by means of a motor (not shown) is provided to drive portion 13 in the vicinity of its attachment with centrifugal pump main body 12. By rotating this drive magnet 25 using the motor, magnet 24 of the centrifugal pump main body 12 can be rotated due to the magnet force from drive magnet 25.
When magnet 24 of centrifugal pump main body 12 is rotated by drive portion 13, rotating body 23 which has vanes 22,22 rotates. An eddy is generated in the blood within centrifuge chamber 15 by the vanes 22,22. The pressure on the outer periphery inside centrifuge chamber 15 becomes high, while the pressure in the vicinity blood inlet 17 becomes low.
In other words, a pressure difference is generated between the outer periphery of centrifuge chamber 15 and the vicinity of blood outlet 17. Blood is drawn from blood inlet 17, and blood in centrifuge chamber 15 is sent out from blood outlet 18.
Vessel 14 of the aforementioned centrifugal pump main body 12 is formed by assembling a funnel shaped body 31 (see FIG. 6) which forms centrifuge chamber 15 and a outlet portion 32 (see FIG. 7) which forms blood outlet 18.
The inner peripheral surface of centrifuge chamber 15 of the vessel 14 formed in the above described manner must be formed in a tapered shape which progressively widens in the direction moving away from blood inlet 17 so that funnel shaped body 31 can be withdrawn. For this reason, when circulation of the blood is initiated, as shown in FIG. 8, air bubbles
REFERENCES:
patent: 4401431 (1983-08-01), Arp
patent: 4643641 (1987-02-01), Clausen et al.
patent: 5084244 (1992-01-01), Muramoto
patent: 5316440 (1994-05-01), Kijima et al.
patent: 5437634 (1995-08-01), Amano
Aizawa Takeshi
Ishii Shuichi
Ito Kazuyuki
Kuwana Katsuyuki
Matsuura Motonori
McAndrews, Jr. Roland
Senko Medical Instrument Mfg. Co. Ltd.
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