Patent Application
20080017577
For purposes of the description hereinafter, spatial orientation terms, if used, shall relate to the referenced embodiment as it is oriented in the accompanying drawing figures or otherwise described in the following detailed description. However, it is to be understood that the embodiments described hereinafter may assume many alternative variations and embodiments. It is also to be understood that the specific devices illustrated in the accompanying drawing figures and described herein are simply exemplary and should not be considered as limiting.
In one embodiment, a fluid sample collection device suitable for the collection of a blood sample and the separation of plasma, serum, or other fluid specimens from the cellular material (i.e., blood cells) of the blood sample is disclosed. However, the device described herein is generally applicable for separating solution (i.e., liquids) from solids like a filtration device. In particular, in one form, the device is adapted for collection of a blood sample through conventional sampling techniques and subsequent separation thereof by use of an assembly of components generally including an inner container, an outer container, and a closure member. The inner container generally draws plasma, serum, or other liquid specimens through a porous membrane, filter, or like separating member from the outer evacuated container to separate the plasma, serum, and/or other liquid specimen from the sample.
Referring initially to
Outer container 12 is a generally cylindrical-shaped structure comprising a tubular sidewall 18 defining a first open or top end 20 and further forming a second closed or bottom end 22 of the outer container 12. The closed end 22 may have a rounded or arcuate form as a conventional blood collection tube. Outer container 12 is sealed at open end 20 by closure 16 which is a pierceable component formed of rubber or molded plastic material but may be made of any pierceable elastomeric material. While closure 16 is generally akin to rubber or plastic tube stoppers known in the medical art, closure 16 possess several novel features in its own right as discussed herein. Closure 16 is surrounded, at least in part, by a cap structure or member 24 which is included for protecting the closure 16 when seated within the open end 20 of outer container 12. Cap member 24 is formed with an annular end wall 26 and a depending sidewall or skirt 28 which is configured to extend downward along sidewall 18 of outer container 12 when closure 16 is seated within the open end 20 of the outer container 12. As discussed herein, closure 16 includes an insertable portion which is seated within the open end 20 of outer container 12 and which is held therein by frictional engagement with the inner surface or side of sidewall 18 and/or with an adhesive. Sidewall 28 of cap member 24 extends downward along the outer surface or side of sidewall 18 of outer container 12 to protect the exposed portion of closure 16 extending outward from the open end 20 of the outer container 12. Annular end wall 26 defines a central aperture 30 to expose a portion of closure 16 to allow access to the interior of outer container 12, which is typically accessed by a piercing element, such as a needle cannula, which is inserted through the pierceable closure 16 as described in greater detail herein.
Closure 16 is typically a unitary structure or body formed of rubber, plastic or another similar polymeric material, as described previously, and is generally an elastomeric closure element that is formed of suitable material capable of forming a substantially gas and liquid-tight seal with the open end 20 of outer container 12. Additionally, the body of closure 16 is desirably capable of being punctured with a puncturing device, such as a needle cannula, as described previously. Such a needle cannula may be part of a blood collection device used to transfer blood into outer container 12. Closure 16 is formed with a flanged head or cap portion 32 and a depending and integrally molded plug portion 34. Cap portion 32 is adapted to seat or rest on a rim 36 defined by sidewall 18 of outer container 12 at the open end 20 of the outer container 12. Plug portion 34 is generally adapted to be inserted into the open end 20 of outer container 12 and extend inward into the outer container 12 and form a substantially gas and liquid-tight seal with the inner surface or side of sidewall 18. Thus, with plug portion 34 of closure 16 seated within the open end 20 of outer container 12, a first interior chamber 38 is defined or formed within the outer container 12. First interior chamber 38 may be placed under negative (i.e., vacuum) pressure with respect to external atmospheric pressure prior to sealing closure 16 in the open end 20 of outer container 12, such that the interior of outer container 12 is under negative (i.e., vacuum) pressure. For example, after assembly of device 10 wherein inner container 14 is inserted in outer container 12, the outer container 12 may be evacuated and subsequently sealed with closure 16 thereby placing first interior chamber 38 under negative (i.e., vacuum) pressure and simultaneously placing the interior of inner container 14 under negative (i.e., vacuum) pressure.
Another aspect of device 10 relates to inner container 14 being movable within outer container 12 to accomplish full separation of the collected fluid sample. As shown in
Cap portion 32 of closure 16 defines a top surface 42 which is typically partially enclosed by the annular end wall 26 of cap member 24. Top surface 42 is exposed in the open area defined by central aperture 30 in cap member 24, and this exposed area of top surface 42 is where a user of device 10 inserts a needle cannula or like piercing element to access the interior of outer container 12 and first interior chamber 38 in particular. Accordingly, to provide a blood sample to the first interior chamber 38, a needle cannula or like piercing element of a blood collection device is used to penetrate the exposed portion of the top surface 42 of cap portion 32 of closure 16 which places the first interior chamber 38 in fluid communication with a needle inserted into a patient's vein for blood collection purposes. Since first interior chamber 38 is sealed and under negative (i.e., vacuum) pressure, blood flows from the vein, through the blood collection device, and into the first interior chamber 38 via the needle cannula inserted through closure 16. If desired, the top surface 42 of cap portion 32 of closure may be recessed or otherwise shaped to provide a visual indication or cue of where to insert a needle cannula to appropriately penetrate the closure 16 and access the interior of outer container 12 without striking inner container 14. This recessed or shaped area is designated by reference numeral 44 in
Second or inner container 14 is a generally tubular or cylindrical structure in analogous manner to outer container 12 but may take other forms. Inner container 14 is desirably contained fully within outer container 12 and is initially associated with and supported by closure 16 to extend into the outer container 12. In one embodiment, inner container 14 is a generally bell-shaped structure or unitary body which includes a first or distal end 50 and a second or proximal end 52. Inner container 14 is generally comprised by a bell-shaped containment portion 54 defining or forming the distal end 50 and a tubular structure or conduit 56 that extends upward from containment portion 54 and defines or forms the proximal end 52 of the inner container 14. Tubular conduit 56 forming the proximal end 52 of inner container 14 is adapted to engage the bore 46 defined in plug portion 34 of closure 16 whereby the inner container 14 may be suspended within outer container 12. Containment portion 54 is hollow and defines a second interior chamber 58 which is in fluid communication with the upward-extending tubular conduit 56.
In the embodiment illustrated in
As described previously, in one embodiment, inner container 14 depends (i.e., is suspended) from closure 16 and is supported to closure 16 by frictional and/or adhesive engagement of tubular conduit 56 in bore 46 defined in plug portion 34 of the closure 16. Thus, with the foregoing engagement, the proximal end 52 of inner container 14 is secured to closure 16 with the distal end 50 projecting into the first interior chamber 38 when the closure 16 is inserted into and secured in the open end 20 of outer container 12. As shown in
Tubular conduit 56 of inner container 14 further acts as a port which, during use of device 10, is adapted to selectively place the second interior chamber 58 defined by containment portion 54 of inner container 14 in fluid communication the first interior chamber 38 defined by the confines defined by outer container 12 and closure 16. Such a port is generally defined by an opening or port 64 at the end of tubular conduit 56 and, hence, at the proximal end 52 of inner container 14. To allow “outlet” port or opening 64 to be in fluid communication with the interior of outer container 12, tubular conduit 56 is desirably releasably disposed in bore 46 in plug portion 34 of closure 16 and thereby releasably connected to closure 16. Thus, in order for outlet port or opening 64 to be in fluid communication with the fist interior chamber 38, tubular conduit 56 must first be released of engagement with closure 16. Once released of engagement, inner container 14 moves downward within outer container 12 under the force of gravity and/or by force exerted by a user of device 10 as described herein. However, the length of downward movement is limited by limiting structure 40 disposed within outer container 12. In particular, the interference engagement between the distal end 50 of inner container 14 and limiting structure 40 limits downward movement of the inner container 14 within outer container 12 to distance a. Distal end 50 of inner container 14 is desirably fully open so that containment portion 54 defines an end opening 66 for admittance of fluid into the containment portion 54. End opening 66 may be the diameter of containment portion 54 or have a smaller diameter than the containment portion 54.
The second interior chamber 58 defined by inner container 14 and, in particular, by containment portion 54 is separated from the first interior chamber 38 defined by outer container 12 and closure 16 by a porous member or filter element 70. Typically, porous membrane 70 is adapted to separate plasma or serum from a whole blood sample, as will be discussed in more detail herein. Porous membrane 70 is disposed in or over end opening 66 in containment portion 54 and fully covers end opening 66 on an opposite side of a top end or side 72 of the containment portion 54. Additionally, porous membrane 70 may be formed as a disk-shaped structure with a filtering center area which is secured to the distal end 50 of inner container 14 and fully covers end opening 66 in containment portion 54, thereby also forming the distal end of containment portion 54. Porous membrane 70 may be constructed of any suitable material including pores which are large enough to draw plasma or serum therethrough under a normal negative (i.e., vacuum) pressure of a conventional evacuated blood collection tube, but small enough to prevent blood cell cells, including red cells, white blood cells, platelets, etc., and aggregates such as blood clots from passing therethrough. As examples, porous membrane 70 may be comprised of high density polyethylene, high density polypropylene, ceramic, porous metal, porous glass, glass fibers, polyvinyl polymers, paper, natural fibers, and combinations thereof. As used herein, the terms “porous membrane” and “filter” or “filter element” are used interchangeably and can relate further to a column-like filter, a filter paper (i.e., Whateman paper), two or more stacked filter papers, a single membrane, or multiple membranes. Variations of the structural shape or supporting structure of porous membrane 70 are therefore contemplated and are within the skill of those skilled in the art. In general, filter paper used for porous membrane 70 is suitable for separating cells from plasma/serum and a membrane 70 with a selected pore size according to the molecular weights of proteins may be used to separate proteins which are smaller than the selected pore size from a collected blood sample.
The pore size of porous membrane 70 may be varied according to the required selectivity need by the user in separating a fluid sample. For example, the pore size of porous membrane 70 may be selected to achieve a selectivity according to the molecular weight of molecules desired to pass through the membrane. A pore size of 60,000 Daltons is used to prevent proteins or other macormolecules with 60,000 or higher molecular weight from passing to the second interior chamber 58. Alternatively, porous membrane 70 may be adapted to remove albumin, immunoglobulin, and/or other large molecules from the collected plasma or serum. Further, porous membrane 70 may be a molecular weight cut-off membrane of 10,000 Daltons or less for peptide extraction from the blood sample, or a molecular weight cut-off membrane of 2,000 Daltons or less to separate metabolites and other small molecules for biochemical analysis.
A porous membrane 70 having a pore size smaller than 50,000 Daltons allows only molecules smaller than 50,000 Daltons to pass through the porous membrane 70 so that, in addition to cells and clots, albumin, antibodies, and other large molecules remain in outer container 12 and do not pass to inner container 14. This is important in the context of biomarker discovery, as albumin and many other large molecules in high abundance in blood often are not meaningful and can, thus, be easily removed. A porous membrane 70 of 3,000-10,000 in pore size allows only peptides less than about 3,000-10,000 Daltons to pass through. These peptides are ready for proteomic and diagnostic analysis. For general plasma or serum collection, a regular filter paper or porous membrane with a 0.45-1.0 μm pore size can be used for porous membrane 70. This porous membrane 70 can remove all blood cells including platelets and, therefore, the collected plasma or serum in inner container 14 is a platelet-free sample. As a further example, when a porous membrane 70 with a pore size of about 0.22 μm is used, bacteria cells and viral particles, such as HIV, in addition to all blood cells, will not pass to inner container 14 and will be retained in lower chamber portion 62. As a result, the plasma or serum collected in inner container 14 will be free of infection, providing bio-safety plasma or serum samples for downstream laboratory analysis. A desirable pore size range for the removal of bacteria cells and viral particles is about 0.1 μm to 2 μm. Membranes with pore sizes of 3,000, 10,000, 30,000, 50,000, 100,000, and 200,000 Daltons are commercially available.
It is contemplated that outer container 12 may include cell metabolism regulators, an agglutinating agent, and/or an anticoagulant therein. Agglutinating agents are used to create large aggregates of cells, which facilitates the filtering process. Suitable agglutinating agents include, but are not limited to, lectins, such as potato or wheat lectins. Alternative agglutinating agents may include antibodies with an affinity for blood cells attached to microbeads. The agglutinating agent may also be in the form of a solution, pellet, pill, or lyophilized specimen, such as granules, coated on a separate structure or coated on an inner surface of outer container 12, and/or both outer and inner surfaces of inner container 14. An anticoagulant such as heparin, EDTA, sodium citrate, or other known compound for preventing coagulation of blood can also be used. The term “agglutinating agent” is used to denote the use of an agglutinating agent alone to form cell aggregates, or the use of an agglutinating agent in combination with a structure that can impart desired properties to the cellular aggregates. For example, the structure may be a microbead of a particular density, coated with an agglutinating agent. In another example, the structure can have a specific geometry, such as a string or cylinder, to impart a desired shape to the aggregates, such as a shape that is less densely packed than cellular aggregates without the structure, and which permits plasma to pass through the aggregates. The foregoing examples are not intended to be limiting, and any structure having the desired properties may be used as the starting particles for forming the cellular aggregates. In all embodiments described herein, the term “agglutinating agent” will refer to the use of an agglutinating agent alone, or in combination with a structure as described hereinabove, which has been coated with an agglutinating agent.
Inner container 14 may also optionally include an additive or additives similar to those in outer container 12 but which can interact only with the separated liquid, typically plasma or serum. Many additives have been found to cause hemolysis and other damage to blood cells. Accordingly, a benefit of the provided by the dual outer and inner containers 12, 14 structure described in the foregoing description is the ability to place distinct additives in inner container 14 where they will not come into contact with blood cells present in the whole sample (i.e., in first interior chamber 38) thereby reducing any adverse effects to the blood cells. Examples of additives include anticoagulants, detergents, preservatives, and enzymatic inhibitors such as protease inhibitors such as 4-(2-Aminoethyl)-benzenesulfonyl fluoride hydrochloride (AEBSF).
The overall size of outer and inner containers 12, 14 are varied to provide predetermined relative differences in volume between the outer and inner containers 12, 14 and, correspondingly, predetermined relative differences between the upper and lower chamber portions 60, 62. These predetermined relative differences can be chosen according to known characteristics of the collected fluid sample, typically blood. For example, the volume of the lower chamber portion 62 may be designed to be about 5× ml of fluid sample (i.e., blood), while the volume of inner container 14 (including containment portion 54 and tubular conduit 56) is about 3× ml resulting in a ratio of volumes of about 5:3 which corresponds to the volume ratio of cells-pellets to plasma in whole blood. “X” in the foregoing can be any whole number or fraction (i.e., 0.05-10) and can be changed according to the total volume of the first interior chamber 38 in outer container 12. The total volume of the upper chamber portion 60 is about 6× ml and the total sample volume available in device 10 is about 8× ml in the foregoing example.
To assemble device 10, inner container 14 is affixed to closure 16 by inserting tubular conduit 56 into bore 46 in plug portion 34 of the closure 16 forming an assembly structure comprised of inner container 14 and closure 16, with inner container 14 suspended or depending from closure 16. Outer container 12 and the assembly of inner container 14 and closure 16 are placed into an evacuator and, when a desired vacuum level is reached, inner container 14 and closure 16 are inserted into the open end 20 of outer container 12. Once this assembly is disposed in outer container 12, plug portion 34 of closure 16 is inserted into the open end 20 of outer container 12 which engages the inner surface of sidewall 18 of the outer container 12 and forms a gas and liquid-tight seal with the inner surface of the sidewall 18. Cap portion 32 of closure 16 rests on the rim 36 of outer container 12. Typically, cap member 24 is preassembled to closure 16, with annular end wall 26 engaged with the top surface 42 of cap portion 32 of the closure 16 and the sidewall 28 of the cap portion 32 extending around the circumference of closure 16. With closure 16 sealed in the open end 20 of outer container 12, both the first interior chamber 38 defined by outer container 12 and the second interior chamber 58 defined by inner container 14 are at negative (i.e., vacuum) pressure. Device 10 is now ready for a fluid collection and separation procedure.
Referring further to
With the level of blood sample B in outer container 12 being above porous membrane 70 and a residual vacuum being present within inner container 14, a pressure differential exists between the outer container 12 and inner container 14, with the first interior chamber 38 in the outer chamber 12 being at a higher pressure than the second interior chamber 58 in inner container 14. This pressure differential forces the liquid portion of the collected blood sample B, which is plasma or serum (hereinafter “P/S”), through filtering porous membrane 70. In particular, plasma or serum P/S passes through porous filter 70 in the direction of arrow A1 and enters the second interior chamber 58 defined by inner container 14 and containment portion 54 of inner container 14 in particular, while the blood sample B moves in the opposite direction to arrow A1 (i.e., downward) in outer container 12. Porous membrane 70 prevents cellular material and platelets (hereinafter “C/P”) from entering the second interior chamber 58 defined by inner chamber 14 and containment portion 54 in particular. At this point, as illustrated in
Referring now in particular to
With the disengagement of inner container 14 from closure 16 as just described, an air pressure equalization is now present between the upper chamber portion 60 of the first interior chamber 38 in outer container 12 and the second interior chamber 58 in inner container 14. However, with the downward movement of inner container 14 within outer container 12, additional height differential exists between the level of blood sample B in the upper chamber portion 60 of the first interior chamber 38 and the level of separated plasma or serum P/S in the second interior chamber 58. This height differential provides additional pressure differential which “presses” additional plasma or serum through porous membrane 70. Separation of plasma or serum P/S continues until the level of plasma or serum P/S in the second interior chamber 58 in inner container 14 substantially equalizes with the level of cellular material/platelets C/P in the first interior chamber 38 in outer container 12, as substantially shown in
As will be appreciated from the foregoing blood collection and separation example, closure 16 may be removed and inner container 14 removed from outer container 12. Plasma or serum P/S present in the second interior chamber 58 in inner container 14 can then be accessed for downstream tests. Additionally, the first interior chamber 38 in outer container 12 contains primarily cellular material and platelets C/P which again can be removed for downstream testing.
Referring to
The radially offset configuration of tubular conduit 56a provides additional clearance to one side of the tubular conduit 56a for insertion of needle cannula N into outer container 12a, as shown in
In use, device 10b collects a fluid sample in the manner described previously. Such a collection procedure begins with the insertion of needle cannula N through closure 16b and the depositing of a fluid sample in the first interior chamber 38b in outer container 12b. Separation of the fluid sample commences as described previously in connection with device 10. As shown in
In
While several embodiments of a fluid sample collection device and method were described in the foregoing detailed description, those skilled in the art may make modifications and alterations to these embodiments without departing from the scope and spirit of the invention. Accordingly, the foregoing description is intended to be illustrative rather than restrictive. The invention described hereinabove is defined by the appended claims and all changes to the invention that fall within the meaning and the range of equivalency of the claims are embraced within their scope.
