Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
  • B01D67/0081—After-treatment of organic or inorganic membranes
  • B01D67/0088—Physical treatment with compounds, e.g. swelling, coating or impregnation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes

Definitions

• the invention generally relates to filter devices. More particularly, the invention relates to filter devices utilizing hydrophobic filter material. The invention also generally relates to the wetting of porous hydrophobic material.
• the clinically proven cellular components of whole blood include red cells, which can be used to treat chronic anemia; and platelets, which can be used to treat thrombocytopenia.
• the clinically proven noncellular components of whole blood include plasma and plasma-based fractions, such as albumin, protein fraction, gamma globulin, and various other specific coagulation protein concentrates.
• the present concensus is that patient care is improved by providing only the therapeutic components of whole blood which are required to treat the specific disease.
• the demand for therapeutic components of whole blood is thus ever increasing.
• the demand for safe and effective systems and methods for collecting, separating and storing the cellular and noncellular components of whole blood grows accordingly.
• Whole blood can be separated into its cellular and noncellular components by filtration.
• blood filtration devices utilize hydrophobic microporous material. Because the material is hydrophobic, the membrane needs first to be “wetted” to accommodate fluid flow through the membrane. A porous membrane has been "wetted” when the pore volume of the membrane has been completely filled with a liquid.
• a conventional method of wetting hydrophobic materials includes the application of surfactants, alcohol, or other fluids which spontaneously wet the hydrophobic material.
• surfactants for example, attention is directed to the copending U.S. Patent Application of Boggs et al, entitled “WETTABLE HYDROPHOBIC HOLLOW FIBERS", Serial No. 387,988, filed June 14, 1982.
• Another conventional wetting method involves the use of chemical means to alter the surface characteristics of the material.
• conventional wetting techniques involve the introduction of nonphysiological substances into the pore volume of the filter material. They also require the subsequent step of washing or flushing the nonphysiological substances from the pore volume of the filter material prior to use. Regardless of the thoroughness of the washing step, however, there is the possibility that traces of the nonphysiological substances used to wet the filter material will remain associated with the material.
• conventional substances which spontaneously wet hydrophobic materials may craze, or stress crack, plastic housings in which the hydrophobic materials are carried. Cracks and actual leaks in the housing can develop.
• the invention provides a device having a porous material which has been wetted without the use of a substance which, would spontaneously wet the material.
• a liquid which does not spontaneously wet the porous material can nevertheless be forced into the pore volume of the material.
• the porous material is wetted with, a liquid which would not spontaneously wet the material.
• the porous material is first subjected to reduced pressure or a vacuum prior to exposure to the pressurized liquid. It is believed that this additional step facilitates the overall effectiveness of the wetting process conducted in accordance with the invention.
• a physiological liquid such as water or an aqueous saline solution
• a physiological liquid such as water or an aqueous saline solution
• a physiological liquid can be used alone to wet a hydrophobic microporous membrane. Exposure of the membrane to surfactants or other nonphysiological liquids can thereby be completely avoided.
• the resulting filter device is preprimed with the physiological liquid and ready for immediate use, without any subsequent washing step and without the possibility of residual traces of surfactant or other nonphysiological substances.
• Figure 1 is a perspective view of a prewetted and preprimed filter device which embodies the features of the invention
• Figure 2 is a partially cut away perspective view of the prewetted and preprimed filter device shown in Figure 1;
• Figure 3 is a partially perspective view of a filter device and an apparatus which may be used to wet and preprime the filter device in accordance with the invention.
• Figure 4 is a perspective view of a filter device and an alternate apparatus which may be used to wet and preprime the filter device in accordance with the invention.
• a prewetted and preprimed filter 10 which embodies the features of the invention is shown in Figs. 1 and 2.
• the filter 10 can be variously constructed and used for different purposes. Because the invention is well suited for use with medical purpose filters, in the illustrated embodiment, the filter 10 is one suitable for separating the cellular and noncellular components of whole blood.
• the filter 10 includes a housing 12, which can be molded from a plastic material.
• the housing 12 includes end caps 14 and 16 which have suitable blood outlet and inlet ports, respectively 18 and 20.
• the housing 12 also includes a plasma port 22 and an optional fill port 24, the purpose of which will be explained later.
• a porous hydrophobic filter material 17, illustrated in Figure 2 is contained within the housing 12.
• the hydrophobic filter material 17 consists of a plurality of hollow microporous fibers 27 having a desired pore size. It should be appreciated that the filter material 17 can be alternately configured, such as in a flat sheet.
• the pore size and porosity of the hydrophobic material will depend on the particular filter application and is not a limitation on the general aspects of the invention.
• the pore size will generally be chosen on the basis of the components to be removed or the type of treatment that is desired.
• the desired pore size to separate cellular blood components from noncellular blood components is well known in the art.
• Suitable types of such microporous hydrophobic materials include those manufactured from polypropylene, for example.
• Other suitable types of such hydrophobic microporous membrane materials include those constructed of polyethylene.
• the filter 10 can be constructed by any suitable method.
• the bundle of the hydrophobic filter fibers 27 can be placed in housing 12 in a direction substantially parallel to the longitudinal axis of housing 12 and secured at both ends within housing 12 by use of a suitable potting compound.
• This concept is well known in the art and is not a limitation on the invention as any suitable construction can be used.
• a liquid 26 fills the interior of housing 12 and the pore volume of the hydrophobic hollow fibers 27.
• the liquid 26 is retained in the housing 12 by end caps 19, 21, 23, and 25 which seal the respective ports 18, 20, 22, and 24.
• the liquid fills the interior of housing 12 and the pore volume of the hydrophobic hollow fibers 27.
• the liquid 26 is retained in the housing 12 by end caps 19, 21, 23, and 25 which seal the respective ports 18, 20, 22, and 24.
• the liquid fills the interior of housing 12 and the pore volume of the hydrophobic hollow fibers 27.
• the liquid 26 is retained in the housing 12 by end caps 19, 21, 23, and 25 which seal the respective ports 18,
• FIG 3 an apparatus is shown which may be used to prewet and preprime the filter devices 54 and 56 in accordance with the invention.
• the apparatus includes a chamber 30 and peripheral equipment 32 for providing air and other fluids under pressure.
• Chamber 30 is designed to withstand positive and negative pressures.
• the peripheral equipment 32 includes lines for the delivery of fluid under pressure to chamber 30.
• the peripheral equipment 32 includes a solution line 34 and a liquid storage tank 36 having a valve 38.
• the liquid 26 in the tank 36 does not include any surfactant or the like which would spontaneously wet the porous material of the filter devices 54 and 56.
• the peripheral equipment 32 also includes a pressure and vacuum line 40 which communicates with the interior of the chamber 30.
• the line 40 includes suitable valves 42, 44, and 45; a vacuum source 47; a pressure regulator 46; and a source of compressed gas 48.
• a vent line 50 with a valve 52 is also provided for venting the chamber 30.
• valves 38, 42, 44, 45, and 52 are initially closed.
• the filter devices 54 and 56 similar to the filter 10, but not yet filled with the liquid 26, are placed in the chamber 30.
• One or more of the inlet and/or exit ports 18, 20, 22, and 24 of each of filters 54 and 56 are opened. It should be appreciated that, in accordance with the invention, only one of the inlet or outlet ports 18, 20, 22, and 24 associated with each filter 54 and 56 need be open.
• each filter 54 and 56 including the pore volume of each associated hollow fiber, are thereby evacuated through the open port or ports.
• valves 42 and 44 are again closed.
• the valve 38 is opened, and the chamber 30 is filled with the liquid 26 from the storage tank 36 via the solution line 34.
• the interior of each filter 54 and 56 is also thereby filled through the open port or ports.
• valve 38 is closed.
• the valve 45 is opened, and the interior of chamber 30 is pressurized by compressed gas from the compressed gas source 48.
• the pressure regulator 46 is utilized to provide the desired pressure.
• the liquid 26 used to achieve the surprising results of the invention can comprise virtually any liquid which does not spontaneously wet the porous filter material.
• the liquid 26 can comprise only water.
• the liquid 26 can also be a solution containing water, such as an aqueous saline solution.
• an aqueous saline solution In the context of the illustrated embodiment, the use of the aqueous saline solution is preferred.
• the valve 45 is closed, the valve 52 is opened, and the chamber 30 is vented via the vent line 50.
• the filters 54 and 56 can then be removed from chamber 30.
• the ports which were opened during the wetting process are closed, using the heretofore discussed caps, to retain the liquid 26 in the filter housing.
• the filter 10 as shown in Figs. 1 and 2 is thereby provided in which the previously unwetted hydrophobic fibers are now in a fully wetted condition.
• the liquid 26 remains in the housing 12 until time of use.
• the filter 10 is thus not only prewetted, but is also preprimed.
• the prewetted and preprimed filter 10 can be sterilized by autoclaving, radiation sterilization, or the like.
• the above-discussed step of first evacuating the chamber 30 prior to subjecting the filter material to the pressurized liquid 26 serves to facilitate wetting process.
• air which is normally present within the pore volume of the material is removed.
• the liquid 26, which is thereafter forced into the pore volume under pressure, will then remain in the pore volume after the pressure is removed. Otherwise, it is believed that air compressed within the pore volume by the entry of the pressurized liquid 26 could expand after the pressure is removed and force the liquid 26 from the pore volume.
• the initial evacuation step could be eliminated and other methods used to remove the air from the pore volume.
• the air present in the pore volume can be driven, or dissolved, into solution.
• This alternative technique could be enhanced by first purging the pore volume with carbon dioxide or another gas which will readily dissolve in the liquid 26. Any comparable technique which serves to increase the overall diffusion of gas into solution can also be utilized, such as the application of heat.
• the introduction of the pressurized liquid could be followed by a sudden decrease in pressure on one side of the porous material. This will rapidly draw the fluid through the pore volume toward the side of lesser pressure to effectively "flush" the air from the pore volume.
• the filter housing 12 could itself serve as the equivalent of pressure chamber 30.
• the housing 12 would be made of a material sufficient to withstand the pressures applied.
• the chamber 30 could be eliminated, and the lines 34 and 40 would be attached directly to the desired inlet and/or outlet ports or ports of the filter, as generally shown in Fig. 4.
• an air pressure chamber 58 is provided having a gas pressure line 62 which communicates with a source of compressed air.
• a filter 60 which is of similar design to filter 10 but not yet filled with the liquid 26, is placed within the chamber 58.
• a fluid line 64 communicates directly with at least one of the ports 66, 70, or 72. The fluid line 64 does not communicate with the chamber 58. In the illustrated embodiment, the line 64 communicates directly with the plasma port 66 and blood exit port 72.
• the liquid 26 is thus directed under pressure through the line 64 directly into the interior of filter 60.
• the interior of chamber 58 is at the same time pressurized to an external air pressure generally equal to the internal fluid pressure.
• This arrangement prevents the filter housing 12 from exploding as the pressurized liquid is driven into the pore volume of the filter material.
• all of the inlet and outlet ports 18, 20, and 22 of the filter 10 could have their final closure caps 19, 21, and 23 preattached.
• the pressurized liquid 26 could be introduced into the filter device via the separate fill port 24, as shown in Figs. 1 and 2.
• the fill port 24 could communicate with either the blood side or plasma side of the filter material, or both sides. After the filter material has been wetted, the fill port 24 could then be closed by its own cap 25.
• one of the inlet or outlet blood ports 18 or 20 could be closed, and a stream of pressurized liquid 26 directed through the other open port 18 or 20.
• the pressurized stream of the liquid 26 will be forced through the pore volume of the filter material and exit the filter housing 12 via the plasma port 22, which is left open.
• the pressurized stream of the liquid 26 alone wets the filter material.
• the liquid 26 could include a surfactant present in an amount substantially less than that required to spontaneously wet the filter material. The presence of small amounts of the surfactant will reduce the overall amount of pressure required to force the liquid 26 into the pore volume of the filter material.
• the porous material of the filter is wetted without the use of any surfactant or other nonphysiological material that spontaneously wets the hydrophobic material.
• EXAMPLE I A filter device similar to that shown in Figure 1 was wetted and preprimed in accordance with the invention.
• the microporous filter media which was utilized in the filter was a hydrophobic polypropylene hollow fiber material having the following physical specifications: inside diameter
• the filter was placed in the chamber 30. With all of the filter ports open, the chamber 30 was evacuated to about 0.3 inches of mercury absolute. The chamber 30 was then filled only with saline and thereafter pressurized to about 150 psi for less than one minute. The filter was removed from the chamber and tested by connecting the blood inlet of the filter to a low pressure water line. The blood outlet was closed, and water exited freely from the plasma exit port.
• EXAMPLE II Another filter device similar to that shown in Fig. 1 was wetted and preprimed in accordance with the invention.
• the microporous filter material used was the same polypropylene same hollow fiber material described in Example I. In this procedure, no external chamber was used.
• the blood outlet side of the device was closed.
• the plasma outlet side was opened.
• a pressurized stream of water was directed for approximately one minute through the blood inlet side at about 95 psi.
• the pressurized stream of water exited the device via the open plasma outlet side at a flow rate of about 22 liters per minute, indicating that the hydrophobic filter material had been wetted.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• External Artificial Organs (AREA)
• Infusion, Injection, And Reservoir Apparatuses (AREA)
• Filtering Materials (AREA)
• Cigarettes, Filters, And Manufacturing Of Filters (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=23863492

Family Applications (1)

Country Status (6)

Families Citing this family (4)

Citations (4)

Family Cites Families (3)

• 1983
  • 1983-12-19 WO PCT/US1983/002004 patent/WO1984003229A1/en not_active Application Discontinuation
  • 1983-12-19 EP EP19840900569 patent/EP0135511A4/en not_active Withdrawn
  • 1983-12-19 AU AU24350/84A patent/AU2435084A/en not_active Abandoned
  • 1983-12-19 JP JP84500655A patent/JPS60500560A/ja active Pending
• 1984
  • 1984-01-06 ZA ZA84124A patent/ZA84124B/xx unknown
  • 1984-02-17 IT IT19696/84A patent/IT1173303B/it active

Patent Citations (4)

Also Published As

Similar Documents

Legal Events