Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/36—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests with means for eliminating or preventing injection or infusion of air into body
  • A61M5/38—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests with means for eliminating or preventing injection or infusion of air into body using hydrophilic or hydrophobic filters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D19/00—Degasification of liquids
  • B01D19/0031—Degasification of liquids by filtration
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
  • B01D61/14—Ultrafiltration; Microfiltration
  • B01D61/18—Apparatus therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
  • B01D63/08—Flat membrane modules

Definitions

• This invention relates generally to filter devices and, more particularly, to an intravenous gas- separating filter device employing a hydrophobic membrane which is configured for use such that substantially all gas is separated and vented at the hydrophobic membrane.
• This device can include a hydrophilic membrane for particulate filtering and redundancy of the gas-separating function.
• fluids such as blood, plasma, or other solutions
• gas-separating filter When fluids, such as blood, plasma, or other solutions, are introduced into the body intravenously, it is important to remove any gas or air suspended in the fluid and thereby eliminate any risk of an embolism from gas or air reaching the patient.
• the removal of such gas or air from the fluid is typically accomplished by use of a gas-separating filter.
• the typical features of intravenous gas- separating filters include an inlet chamber and an outlet chamber separated by a hydrophilic membrane.
• the hydrophilic membrane permits the passage of liquid and prevents the passage of gas.
• liquid passes through the hydrophilic membrane from the inlet chamber to the outlet chamber while gas is retained in the inlet chamber and vented to atmosphere.
• a hydrophobic membrane is employed in connection with a vent in the inlet chamber in order to vent the gas which collects in the inlet chamber. See for example U.S. Patent Nos. 4,906,260, 4,190,426, and 3,854,907.
• an intravenous gas-separating filter device it is desirable to configure an intravenous gas-separating filter device so that it will start up (conventionally referred to as "priming") and function in any orientation relative to the ground.
• a relatively low internal volume device having an inlet chamber with a minimal volume is preferable in order to minimize the amount of air that must be initially vented from the inlet chamber. In use, a low internal volume filter can be quickly primed and initially vented.
• gas-separating filter devices are dependent upon the integrity of the hydrophilic membrane separating the inlet chamber from the outlet chamber.
• a disintegration or absence of the hydrophilic membrane in prior art filters would cause them to malfunction. It would be desirable to construct a filter that would continue to filter air or gas from the liquid in the event of disintegration or absence of the hydrophilic membrane. It would be desirable to separate gas and air from liquid in the inlet chamber prior to its passage through the hydrophilic membrane, thereby desirably providing a redundant filtering action for consistent and reliable operation.
• the gas-separating filter device in accordance with the present invention is configured for highly reliable and consistent filtering of gas and air. Significantly, this is achieved by providing a hydrophobic membrane in operative association with a vent opening, with control of liquid flow cooperating with the venting arrangement to substantially completely effect filtering and venting of all gas through the vent opening. While it is presently preferred that the present filter also be provided with a hydrophilic membrane to facilitate particulate filtering, it is specifically contemplated that gas separation be substantially completely effected without reliance upon the hydrophilic membrane.
• the filter device in accordance with the illustrated embodiment of the invention includes a filter housing having a cover portion and a base portion in confronting relationship with each other.
• a hydrophilic filter membrane is interposed between the cover and base portions of said housing and thereby defines an inlet chamber and an outlet chamber.
• An inlet port is joined in fluid flow communication with the inlet chamber.
• An outlet port is joined in fluid flow communication with the outlet chamber.
• a first vent opening communicates with the inlet chamber upstream of the hydrophilic filter membrane for venting gas from liquid passing through the filter assembly.
• a hydrophobic filter membrane is positioned adjacent to said vent opening for preventing liquid from flowing through the vent opening while permitting gas flow therethrough so that gas is separated from liquid flow.
• a second vent opening communicates with the inlet chamber substantially adjacent the hydrophilic membrane downstream of the first vent opening.
• a second hydrophobic filter membrane is adjacent the second vent opening for permitting flow of gas (but not liquid) therethrough and thereby initially venting air from the inlet chamber during initial flow of liquid into the filter assembly.
• the separation of gas from liquid flowing adjacent the first vent opening is promoted by a relatively narrow liquid flow region adjacent the first vent opening.
• a weir element may optionally be employed to define the narrow liquid flow region.
• At least one stand-off projection on the exterior of the housing is positioned in proximity to the vent openings to inhibit exterior blockage of the openings.
• a pair of stand-off projections are positioned in flanking relationship to the vent openings.
• the filter assembly is substantially disc-shaped. Inlet and outlet ports are diametrically opposed on opposite ends of the housing. The first and second vent openings are generally aligned with the inlet and outlet ports. The stand-off projections are generally aligned with the inlet and outlet ports in flanking relationship to the vent openings.
• the hydrophilic filter membrane is D- shaped.
• the filter assembly has a separation chamber having a vent opening wherein the back pressure in the filter combined with the narrow flow region in the separation chamber and a sufficient residence time within the chamber cause all gas in the fluid/gas mixture to pass through the vent opening.
• FIG. 1 is a perspective view of a intravenous gas-separating filter device in accordance with the invention
• FIG. 2 is an exploded perspective view of the filter device shown in FIG. 1;
• FIG. 3 is a cross-sectional view taken along the line 3-3 in FIG. l;
• FIG. 4 is a cross-sectional view taken along the line 4-4 in FIG. 1;
• FIG. 5 is a cross-sectional elevational view of a model filter device in accordance with the invention.
• FIG. 6 is a cross-sectional view taken along the line 6-6 in FIG. 5;
• FIG 7. is a model filter device as shown in FIG. 5 wherein a gas film is venting; and FIG. 8 is a model filter device as shown in
• FIG. 5 wherein a gas bubble is venting.
• the gas-separating filter assembly 10 in accordance with the invention includes a filter housing 12 comprising a cover portion 14 and a base portion 16 which are fitted together in confronting relationship with each other.
• the cover and base portions are constructed from a rigid, clear plastic material such as an acrylic polymer.
• any rigid transparent material suitable for medical use can be used.
• a hydrophilic filter membrane 18 is interposed between the cover 14 and base 16 portions.
• the hydrophilic filter membrane is a polycell foam material such as Supor material sold by Gelman Sciences, Inc. of Ann Arbor, Michigan.
• any hydrophilic membrane material permitting passage of liquid and preventing passage of gas suitable for medical use can be used.
• the hydrophilic filter membrane 18 is generally D-shaped, as shown in FIG. 2. Referring to FIG. 3, the hydrophilic filter membrane 18 is secured to the base portion 16. The filter membrane 18 may be heat sealed to the base portion 16 or with an adhesive suitable for medical use. The hydrophilic filter membrane 18 divides the housing 12 into an inlet chamber 20 and an outlet chamber 22.
• a plurality of upstanding ribs 23 extend upwardly from the base portion 16 to support the hydrophilic filter membrane 18.
• a plurality of grooves 25 are defined between the ribs 25 to receive fluid in the outlet chamber 22 and direct it to an outlet port 26 (FIGS. 2 and 3) .
• an inlet port 24 is defined on one end of the base portion 16.
• the inlet port 24 is joined in fluid communication with the inlet chamber 20.
• An outlet port 26 is defined at the opposite end of the base portion 16.
• the outlet port 26 is joined in fluid communication with the grooves 25 of the outlet chamber 22.
• the disc-shaped filter housing is approximately 1-5/16 inches in diameter and 5/32 inches thick.
• the inner diameter of the inlet port is approximately 1/8 inches and the inner diameter of the outlet port is approximately 3/32 inches.
• the inlet and outlet ports may be configured to fit as luer fittings (not illustrated) or tube fittings.
• a first vent opening 28 is defined in the cover portion 14 adjacent the inlet port 24 (FIG. 3) .
• the first vent opening 28 is provided with a diameter of 0.051 inches, with a 5 degree taper, as shown.
• the first vent opening 28 communicates with the inlet chamber 20 at a location that is upstream of the hydrophilic filter membrane 18. Liquid entering the inlet chamber 20 passes by the first vent opening 28 before it flows to the hydrophilic filter membrane 18.
• a first hydrophobic filter membrane 30 is positioned adjacent the first vent opening 28 (FIG. 3).
• the first hydrophobic membrane 30 is one manufactured from TeflonTM fibers.
• TeflonTM fibers any hydrophobic membrane material that permits the passage of gas and prevents the passage of liquid and is suitable for medical use can be used.
• the first hydrophobic filter membrane 30 is secured to the cover portion 14 by heat sealing the components or with an adhesive suitable for medical use.
• the first hydrophobic filter membrane 30 permits the passage of gas therethrough out of the inlet chamber 20 through the first vent opening 28. Thus, gas is separated from liquid flow at the first vent opening 28 prior to flow of the liquid to the hydrophilic filter membrane 18.
• the inlet chamber 20 defines a relatively narrow liquid flow region 32 adjacent the first vent opening 28.
• a narrow liquid flow region causes any gas or air entrapped in the liquid flow to pass adjacent the first hydrophobic membrane 30 and through said first vent opening 28.
• the depth of the liquid flow region 32 may be in the range of about 0.015 inches to about 0.060 inches and preferably is about 0.045 inches.
• the narrow liquid flow region 32 may be defined in part by an upstanding weir 34 element (shown in phantom lines in FIG. 3) .
• a second vent opening 36 is defined in the cover portion 14 adjacent the hydrophilic filter membrane 18.
• the vent opening 36 also has a diameter on the order of 0.051 inches, with a 5 degree taper.
• a second hydrophobic filter membrane 38 is secured, for example heat-sealed, to the cover portion 14 and extends across said second vent opening 36 for permitting passage of gas and preventing passage of liquid therethrough.
• the second vent opening 36 permits the quick evacuation of air in the inlet chamber 20 during the initial introduction of fluid into the filter assembly 10.
• the second vent opening 36 is positioned in the inlet chamber 20 at an end opposite the location of the first vent opening 28.
• Stand-off projections 40 are located on the exterior of the cover portion 14 in flanking relationship to the vent openings 28 and 36.
• the stand ⁇ off projections 40 inhibit exterior blockage of the vent openings 28 and 36 when the filter assembly 10 is placed adjacent the skin of the patient or another surface which may potentially cover or block the vent openings 28 and 36.
• an external or internal restrictor or a valve can create a back pressure within the filter assembly 10.
• the back pressure is in the range of 5-15 psig or, more preferably, 10-11 psig.
• the resulting flow rate is in the range of 0.1 cc/hour to 400 cc/hour thus creating sufficient residence time within the filter assembly 10 to substantially separate all gas from the liquid and pass the gas through the first vent opening 28.
• the required vent pressure in the vent membrane is adjusted to provide ready venting. This adjustment is made by controlling the porosity of the vent membrane to contain the fluid and vent the air by back pressure. In some cases, a bacteria barrier is also effected. In a preferred embodiment, the porosity is. 45 microns.
• the filter assembly 10 is connected to an intravenous solution supply at the inlet port 24.
• An intravenous catheter device (not illustrated) is connected to the outlet port 26. Liquid flows into the inlet port 24 and through the filter device 10.
• the filter device 10 is self-priming and functional in any orientation. When liquid initially flows into the filter assembly 10, air is purged from the inlet chamber 20 through the first and second vent openings 28 and 36. As liquid enters the inlet chamber 20, it passes adjacent the first hydrophobic member 30 adjacent the first vent opening 28. The combination of a sufficient back pressure, residence time and narrow fluid flow region 32 adjacent the first vent opening 28 forces all gas or air entrapped in the fluid to pass through the first hydrophobic member 30 and out of the first vent opening 28.
• the hydrophilic membrane 18 acts as a redundant filter means providing a back-up filtering function within the filter assembly.
• the fluid retentive membrane at vent 102 permits venting of gas while retaining fluid at a given back pressure P B .
• a fluid/gas mixture flows from right to left through the separation chamber 103.
• a gas element 104 is shown entering the separation chamber 103 at the bottom of the separation chamber 103.
• V ov velocity of gas through vent
• V GH velocity of gas normal to liquid/gas flow and toward vent membrane 102
• T 2 time for the liquid/gas mixture to travel through the separation chamber 103
• the time T j for the gas element 104 to travel to and through the vent membrane 102 must be less than the time T 2 for the gas/liquid mixture to travel through the separation chamber 103.
• the gas can vent as a film extending across the height H of the chamber 103 or as a bubble, as discussed below.
• a gas film 106 extending across the height H of the chamber 103 is illustrated in FIG. 7.
• V OT V w .
• QGV -- Cn (Area) (Pressure Differential) or
• the time T 2 for the liejuid/gas mixture to travel through the separation chamber 103 is a function of V F/G and L. Therefore,
• V B is determined by turbulence, fluid deflection, natural migration of gas toward the vent, and orientation with respect to gravity.
• V B V ⁇ V B ⁇ ? m P B ⁇ must be less than T 2 as discussed above.
• T 2 LHW . Since Tj ⁇ T 2 , then
• the velocity V B of the bubble can be increased by directing flow of fluid/gas mixture against the vent
• V B can be optimized empirically. Better venting can be achieved by increasing
• T 2 relative to T 1 .
• This can be achieved by reducing H or Q F/G/ and/or increasing V B , ⁇ ⁇ , P B , L or W.
• Film venting is not sensitive to orientation relative to gravity and is easier to control than bubble venting.
• a saline solution is the anticipated fluid in a filter having the following parameters:
• QF/G T 2 is less than T 2 , which should vent, and has been tested to do so.
• V B 0-4.4 x 10 s cm/min
• the filter of the present invention can be used in a variety of medical applications where fluids are administered, as for example, in the intravenous administration of blood, plasma, drugs or saline.

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• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Water Supply & Treatment (AREA)
• Life Sciences & Earth Sciences (AREA)
• Veterinary Medicine (AREA)
• Hematology (AREA)
• Biomedical Technology (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Heart & Thoracic Surgery (AREA)
• Anesthesiology (AREA)
• Vascular Medicine (AREA)
• Emergency Medicine (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Separation By Low-Temperature Treatments (AREA)
• Hydrogen, Water And Hydrids (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

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Citations (2)

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• 1994
  • 1994-08-12 AU AU75255/94A patent/AU678521B2/en not_active Expired - Fee Related
  • 1994-08-12 WO PCT/US1994/009118 patent/WO1995006506A1/en not_active Application Discontinuation
  • 1994-08-12 EP EP94925260A patent/EP0716622A4/de not_active Withdrawn
  • 1994-08-12 CA CA002167932A patent/CA2167932A1/en not_active Abandoned
  • 1994-08-12 JP JP7508131A patent/JPH09502127A/ja active Pending

Patent Citations (2)

Non-Patent Citations (1)

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