Hermetic flow selector valve

Details Hermetic flow selector valve Hermetic flow selector valve

2001-07-17

2004-06-01

Sykes, Angela D. (Department: 3762)

Surgery

Blood drawn and replaced or treated and returned to body

Constituent removed from blood and remainder returned to body

C604S006010, C604S004010, C604S034000, C210S424000, C137S625430

Reexamination Certificate

active

06743193

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to flow-selector valves and particularly such valves that may be used in disposable sterile fluid lines, for example, lines used for extracorporeal blood processes.
2. Background
Hemofiltration, dialysis, hemodiafiltration, and other extracorporeal blood treatments may employ flow selector valves such as Y-valves, four-way valves, and other such devices for redirecting the flow of blood and other fluids such as replacement fluids. For example, the direction of the flow of blood through certain types of filters may be reversed repeatedly to prevent coagulation of blood in regions where the mean flow slows to very low rates. For example, where blood is circulated through tubular media in the context of a dialysis filter, it has been proposed that blood may coagulate on the surface of the inlet header leading to the progressive coagulation of blood. U.S. Pat. No. 5,605,630, proposes occasionally reversing the flow of blood through the filter. A four-way valve is proposed for changing over the flow direction.
In other references, the idea of reversing the flow of blood through a tubular media filter is discussed in connection with other issues. For example, in U.S. Pat. No. 5,894,011, the known technique of switching access lines in the patient to improve the flow through an occluded fistula is automated by the addition of a four-way valve on the patient-side blood circuit. In single-access systems in general, for example as described in U.S. Pat. No. 5,120,303, flow is conventionally reversed through the filter during each draw/return cycle. In the '303 reference, the specification observes that the efficiency of filtration is increased due to the double-passing of the same blood through the filter; that is, each volume of drawn blood is filtered twice. Yet another reference, U.S. Pat. No. 6,189,388 B1, discusses reversing the flow direction of blood through the patient access occasionally in order to quantify an undesirable short-circuit effect that attends their long term use. Still another U.S. Pat. No. 6,177,049 B1 suggests reversing flow through the draw access before treatment while an observer is present to test the accesses for patency or to clear blockage in the accesses.
In copending commonly assigned application titled “Device And Method For Enhancing Performance Of Membranes And Filters,” which is hereby incorporated by reference as if set forth in its entirety herein, a Y-shaped flow selector switch is described in connection with the selective direction of replacement fluid into the blood circuit of a hemofiltration system.
Referring to
FIGS. 1A through 1E
, a number of alternative designs for four-way valves have been developed for blood circuits. Referring to
FIG. 1A
, U.S. Pat. No. 5,894,011, discloses a valve that swaps the connections between pairs of lines
905
and
906
via a pair of rotatably connected disks
901
and
902
, each of which supports one of the pairs of lines
905
and
906
. A seal must be maintained between the disks
901
and
902
and between the respective lines. The device is intended to be operated manually.
Referring to
FIG. 1B
, another four-way valve, disclosed in U.S. Pat. No. 5,605,630, which has been proposed for use in blood lines, has a rotating wheel
910
with channels
911
and
912
defined between the wheel
910
and the inside of a housing
913
. When the wheel is rotated, the channels
911
and
912
shift to join a different pair of lines. This device also has seals.
Referring to
FIG. 1C
, another arrangement is proposed in U.S. Pat. No. 6,177,049. This device has a rotating component
915
with channels
921
and
922
defined within it. As the rotating component
915
is rotated, the channels defined between pairs of lines
917
and
919
change from parallel lines joining one set of corresponding lines to U-shaped channels joining a different set.
Referring to FIGS.
1
D
1
and
1
D
2
, a design, disclosed in U.S. Pat. No. 4,885,087, is very similar to that of FIG.
1
B. This design has a rotator
925
that connects different pairs of lines depending on the position thereby defining two different sets of possible flow channels
926
and
929
or
927
and
931
.
In all of the above designs, the valves are not hermetically sealed. Any seal can be compromised, particularly by microorganisms. Thus, each of the foregoing designs suffers from that drawback. Also, many are expensive and do not lend themselves to automation.
Referring to
FIG. 1E
, another type of four-way valve is formed by interconnecting two tubes
937
and
938
with crossover lines
935
and
936
. This design is disclosed in U.S. Pat. No. 6,189,388 (Hereafter, “U.S. Pat. No. '388”). Tube pinching actuators
941
-
944
are used to force fluid through different channels, depending on which actuators are closed. This device provides a hermetic seal and can be fairly inexpensive, but in a given configuration, significant no-flow areas are defined. These dead spaces can lead to the coagulation of blood, which is undesirable. Also, the interconnection of tubes in this does not lend itself to automated manufacturing.
The design of USP '388 provides an important benefit for sterile fluid lines. Because it has no seals which seal the external environment from the portions that are wetted by sterile fluids, there is no danger of contamination by infiltrating microorganisms or other contaminants. Also, the narrow spaces that attend the presence of seals—small gaps between movable parts and stationary parts—are places where fluid can stagnate, which can cause coagulation of some fluids or other adverse effects, depending on the fluid and application. The design of USP '388, however, does have the serious deficiency of providing very long lengths of tubing in which no flow will occur at any given time while in use. This can lead to stagnation.
There exists in the prior art a need for flow directing valves that combine the features of potentially low cost so that they can be replaced as part of a sterile package, no tendency to create stagnation regions where there is no flow, and the capability of providing a hermetic seal to the environment.
SUMMARY OF THE INVENTION
Briefly, A flow diverting appliance has a flexible valve body to which a number of flow lines are connected. The valve body is deformed to create different flow paths within it. The valve body may be deformed, for example, by pinching it to define press-seals in an enclosed volume inside the valve body. The press seals divide the enclosed volume to form exclusive flow channels which allow communication between some flow lines and permit flow communication between other lines. The invention provides a way of making flow diverters part of a replaceable blood circuit which is fully hermetic and with no dead-end spaces which would allow blood to coagulate.
The valve body may be incorporated in a disposable fluid line for use in extracorporeal blood processing equipment. The valve body may be made integral with multiple flow lines and may define a Y-shaped flow selector, a four-way valve, or other possible configurations. When deformed by actuators, the valve body assumes one of multiple configurations, each defining one or more selectable flow passages. By deforming the valve body, fluid can be made to reverse flow direction or be directed along selected paths.
Portions of the valve body may be made from a flexible polymer such as polyvinylchloride (PVC). The operating temperature and gauge pressure impose constraints on the material thickness, shape, and other features. In a preferred embodiment of a four-way valve, a cylindrical section is ultrasonically sealed around a pair of tubes inserted at each open end forming a sealed bladder. In this embodiment, the material, for example, PVC, has a high degree of resilience and assumes a pillow shape even in the presence of a negative gauge pressure. This structure forms the valve body, which is pinched by anvils to form a seal in the center of the bladder. Two

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