Liquid purification or separation – Processes – Separating
Reexamination Certificate
1998-12-28
2001-06-26
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S314000, C210S316000, C210S434000, C210S436000, C604S406000, C055S318000
Reexamination Certificate
active
06251291
ABSTRACT:
TECHNICAL FIELD
This invention generally relates to systems for receiving, storing, and filtering fluids in preparation for further filtrate processing. More particularly, the invention relates to the processing of blood or other biological fluids.
BACKGROUND ART
A noteworthy application of reservoir-and-filter systems is use in blood and other biological fluid processing. For example, suctioning of blood away from surgical sites may be a high throughput operation if much fluid is quickly generated.
Many state-of-the-art reservoir-and-filter systems are designed having an essentially planar filter disposed so as to divide the reservoir into separated portions. A first portion is intended for containing unfiltered fluid derived from a source while the other portion holds filtrate. Common practice is to orient the filter so that the portions are laterally adjacent to one another with the filter surface situated perpendicular to the force of gravity. Fluid is urged into the reservoir by applying a partial vacuum and passes through the planar filter after enough fluid has been collected in the resevoir to create sufficient head pressure to force the fluid through the filter. Necessarily, such a filter will clog during high throughput usage as there are limited or no safe mechanisms for detaching impurities from the filter during operation. Clogging normally occurs, due to gravity, at the lowest portion of the filter and, with time, reduces the effective operational filtration area and traps a volume of unfiltered fluid. Gradually, the filter will tend to clog at higher and higher levels and trap greater volumes of unfiltered fluid. The ability to efficiently filter the fluid will, with time, be compromised.
SUMMARY OF THE INVENTION
In a first embodiment of the invention, there is provided a reservoir-and-filter system for receiving fluid and for removing impurities from the fluid. The embodiment includes a housing which has at least two cavities. Further, the housing has at least one unfiltered-fluid inlet in fluid communication with the first cavity, and has at least one filtrate outlet in fluid communication with the second cavity. A filter member, is disposed within the housing so as to separate the first cavity from the second cavity. The filter member retains a portion of the impurities while permitting impeded fluid communication between the first and second cavities. In accordance with this embodiment, a filtering trap is also included. The trap may be cup shaped, having an opening, a bottom and sides defining a chamber. Such a filter cup has its opening disposed within the first cavity proximal to the inlet and oriented so as to accept fluid into the chamber and to collect the impurities at the bottom while permitting fluid communication through the sides between the chamber and the first cavity. Further, the depth of a filter cup measures less than the height of the first cavity permitting overflow of fluid from the chamber into the first cavity. Another embodiment further includes a coarse filter shroud disposed so as to provide a funnel shape at the trap opening. The second cavity may, in a preferred embodiment, further include at least one gas outlet adaptable for connection with a source of vacuum.
The reservoir-and-filter system may be used in a range of potential applications. A particular embodiment provides for its use as part of an extracorporeal blood processing apparatus. During certain surgical procedures, it is desirable to expeditiously remove generated blood and by-products from the surgical site. The system facilitates the collection of unfiltered blood. Unwanted blood impurities, residue and clots are then filtered, and the resulting filtrate may be further processed. An embodiment of the system provides that the housing is made from a transparent material which is compatible with blood.
In accordance with another embodiment of the invention, a method for removing impurities from blood within an extracorporeal circuit includes placing a reservoir-and-filter system in the circuit between an unfiltered blood source and a location maintained at lowered pressure, introducing blood to the circuit, and collecting filtrate. The reservoir-and-filter system includes a housing, a filter member, and a filtering trap with features described above.
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Headley Thomas D.
Lamphere David G.
Martin Clifford
Strohl Clair L.
Bromberg & Sunstein LLP
Drodge Joseph W.
Tranfusion Technologies Corporation
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