Surgery – Blood drawn and replaced or treated and returned to body
Reexamination Certificate
1999-11-03
2003-02-11
Casler, Brian L. (Department: 3763)
Surgery
Blood drawn and replaced or treated and returned to body
C604S006090
Reexamination Certificate
active
06517508
ABSTRACT:
BACKGROUND OF THE INVENTION
The field of blood processing primarily comprises hemodialysis and plasmapheresis, although other forms of blood treatment may also be used, for example, hemoperfusion, passing blood through adsorbent cartridges, and the like. To accomplish this, blood sets are used to convey blood from the patient to a blood processing device, and then to return the blood from the device back to the patient. The former blood set is called the arterial set, while the latter set is called the venous set.
In combination, the arterial and venous sets comprise several yards of tubing, and thus are rather cumbersome to handle. Furthermore, cost is of course a critical matter, especially when a patient has a chronic need for treatment as in hemodialysis, so that even small cost savings can add up to a substantial amount over a year or more of repeated usage of disposable arterial and venous sets.
Furthermore, priming of the sets is an issue requiring the skilled attention of technicians, so that any improvement or simplification in the priming process, and other processes of use of the arterial and venous sets, can be valuable.
By this invention, numerous improvements to conventional arterial and venous blood sets are provided for reduction of cost and improved ease and efficiency of use.
DESCRIPTION OF THE INVENTION
By this invention, a combined arterial and venous blood tubing set may be provided for the transport of blood between a patient and a blood processing unit. The combined set comprises an arterial set component which comprises arterial tubing having an arterial patient connector at one end and an arterial unit connector at the other end. A venous set component of the set comprises venous tubing having a venous patient connector at one end and a venous unit connector at the other end.
In accordance with this invention, the arterial and venous patient connectors, and the arterial and venous unit connectors, are respectively substantially and releasably directly connected to each other in such manner that the arterial and venous set components cooperate to form a loop.
This facilitates the installation of the-sets into a hemodialysis machine, for example, resulting in greater ease of installation with a saving of time. Eventually, the set components wind up serving in the normal manner of arterial and venous sets. Even with a relatively small increase or improvement in ease and time saving, the improvement can be quite substantial particularly in the treatment of chronic conditions, as in most hemodialysis, so that the effect of the improvement in time savings can add up to a substantial amount over the course of a year.
Particularly, the arterial and venous unit connectors may be directly connected together with a frangible seal, to permit their breaking apart after the combined set has been primed, for subsequent connection to a blood processing unit.
Thus, the fully primed arterial and venous sets may be directly connected to a reused dialyzer. Solution may then be circulated through the system with air being removed from the dialyzer, but no air being sent to the dialyzer through the primed sets, which reduces the number of air bubbles being trapped within the dialyzer itself. Air coming from the dialyzer will then be typically removed by a bubble trap in the sets, so that it is not recirculated again to the dialyzer.
By this invention, particularly wet, reused dialyzers (or other blood processing devices) can be effectively primed to exhibit improved performance because of a reduced number of trapped air bubbles within the membrane system of the dialyzer.
The arterial and venous patient connectors of the respective arterial and venous sets may optionally be substantially directly connected together by an interconnector tube to permit circulatory priming of the arterial and venous sets, and also to avoid the need of other end closures at the arterial and venous patient connectors, if the arterial and venous sets are supplied to the user in interconnected form as in this invention.
The interconnector tube preferably comprises a tube having a connector such as a female luer connector at each end, for connection with the patient connectors of the arterial and venous sets. Also, the tube may have an attached, integral cap to close an end of the tube after disconnection of one of the patient connectors. Thus, one of the patient connectors may have its sterility preserved while the other patient connector is being attached to a fistula set and access to the patient's bloodstream is being obtained.
Priming of the connected arterial and venous sets can be performed in a manner similar to that disclosed in Utterberg U.S. Pat. No. 5,951,870, preferably with the modifications described below:
The arterial and venous sets respectively preferably have the substantially directly connected end connectors to form a closed loop as described above. One may pass priming solution into and through a portion of the directly connected arterial and venous sets in a first direction that is reversed to the normal direction of blood flow through the sets, while removing air from one of the sets through a branching port from one of the sets.
One also may pass priming solution into a second direction of flow opposite to the first flow direction through the system (which opposite direction is the normal direction of flow through the system) while continuing to remove air from the system through the port, until substantially all air desired is removed from the arterial and venous sets.
Thereafter, with the flow stopped temporarily the unit arterial and venous connectors are separated and connected to the blood processing unit such as a dialyzer preferably with the blood outlet at the top to facilitate bubble removal. One then pumps the priming solution through the arterial and venous sets and the blood processing unit in the second flow direction (i.e., the normal flow direction which is reversed to the first flow direction), to flush the sets and blood processing unit, without passing substantial amounts of air into the blood processing unit.
This method can be accomplished while pumping the solution with a flow pump such as a roller pump through the set, which operates in only a single, pumped flow direction throughout the entire priming process, the normal, second flow direction described above. The first flow direction, which is reverse to the second flow direction, may take place by gravity flow if desired. Preferably, the arterial and venous patient connectors are substantially directly connected together throughout substantially all of the performance of the above method.
The invention also pertains to a tubular medical fluid set having an in-line bubble trap chamber having a top wall. The top wall defines a port which communicates with flow tubing of the tubular set. The port communicates with a port tube which extends into the chamber and has a tube end which is spaced below the top wall, and preferably below the intended blood/air interface. The tube end defines a wall that directs flow out of the tube circumferentially into and through the bubble trap chamber. Thus, blood entering the chamber through the tube is directed circumferentially about the chamber wall, the effect of which is to direct bubbles radially inwardly, rather than downward.
The chamber also preferably defines a baffle to convert circumferential flow into turbulent flow at positions above the tube end wall and the circumferentially directed blood and at the blood-air interface. This prevents formation of a blood whirlpool having a significant, centrally depressed upper surface. Thus, the centrally disposed bubbles will rise to the top of the chamber to join an air space that is typically present there, without being sucked downwardly as would be caused by the presence of such a blood whirlpool having a centrally depressed upper surface.
Accordingly, the flow pattern of blood near the top of the bubble trap chamber described comprises a top segment of largely turbulent blood flow, and a lower segment of la
Andrews Keith
Schnell William J.
Utterberg David S.
Casler Brian L.
DSU Medical Corporation
Ellis Garrettson
Seyfarth Shaw
Thissell Jeremy
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