CA2198654A1 - Bag filter - Google Patents

Abstract

A bag filter having an end that is closed without an end seam is disclosed.

Description

BAG ~IL1~.R
Techni~al Field l~is i~ Lio~- relates to a ba~g iilter, prefelably a bag filter i.:or filtering biological fluidls such as blood or blood ~u~ ents.

S P~ d of the Imrention Bag filters can be used ill ~e~r of filteILng applicahons. Typically, a bag filter is fo.ll,ed from one or more sheets of ~brous r,~,r,~o~ webs that are folded i~to a tubular foIm, and then the adjoining po~ions alld one end ol' t~e tube are sewn together. The resllltin~ bag is hlTned ~nside-o~at, and then the seams are 10 heat-sealed wi~ thermoplastic tape. Ihe bag filter thus produced has two seams, namely a side seam and an end seam.
Bag filters prod--~e~l by se~g and heat-sealin~g have ceItain deficiencies.
Since the seams ha~e been pu~ctured by the sew~ng needle and are held toge~er bythe thread, the s~ructural in~egrit~ of ~e seam~ and hence that of the bag filter itself, 15 is we~ene~l ~o~ , sewn seams can pro~nde ~luid lealcage yatllw;~ during use, thereby allowing u~tered fluid to bypa~s the filter medium~ In ad-3ition~ the metho~ of producing such bag filters is nme-ro~-c!..,.ing and costly because of the number of steps ~nvolved when the seams are sewI~ and heat-sealed with thermoplastic tape.
Some bag filters are formed by me~ely gluing or thermally sedling the seams, i.e, bonding the fibrous web to itself without any se~qng. Al~hough such se~lingtechniques avoid the need to purlcture the hbrous nonwoven web with a se~ing needle, t~e gluing a~d thermal se~ling te~niqve~ also result in two ieams, and suffer from other defidencies. For example, the thermal sealing tPcllnique requi~es the parlial melting of the fibrc~us nollwo.~ web, thereby adversely affecting the structural integri~ and filtering character~st~cs of the bag filter. Additionally, gluing or heat-sealing may fail to pro~ide a strong m~r~a~ical bond, and th.~ filter thus produced may be lln~lit~ble for use in rugged e~ ,..".t~rlt~.
Felt bag filters have been used in car~iotorn~ resen~oirs durinjg surgery to 30 remove surgical debris such as bone c~ips, fat, and clots f~om ~lood before ret~ g the blood to ~he F~hPnt However, these de~ices, which are used iII a~l extraco,~ Qrcuit, have suirel.d from a nl1lTher of defir;~nci~s ~or example, the bag filter may leak and/or lack sllffl~ent st-ucmral ;- t~ for the reasons set folth above. Tb~s, the device i~cl~di~ the bag filter may requirc a~ddi~onal S elern~nt~ e.g.J for ~u~po~l. Additionally or altell~ati~cly the filt~r Dqay lack sufficient dirt capacity to re~"u.~ all of the surgical debris without clogging over the course of the surgical procedure. This carl be a p~cular probler4 since replacing a cardiotomy reservoir during a su~gical protocol can be a labor intensive effort. For ~Y~rle. reFl~cinp the device r~y~. s disco~ f l;"g a mlmber of conduits from the10 de~ice, and then priming the replacement device befo~e use.
MLr~ v.~r, blood i~r~ s ~ amounts of leukocytes, and the cont~ of the blood with the ~a~iO~S ~o~ Jnerlts of the ex~acol~o~cal ci~a~it (e.g, tbe cc.~-tui~, and the ~d;~lolLI~ resen~oir) may c~use the leukocytes in the blood to become a~ at~d. This is a concern sinee these acti~ated leuko~tes may inflict 15 damage to int~ l organs. The acti~rated leuko~ytes may relea~?e ag~ents that can disrupt and destroy nor~ cellular fllnc~iQnc~ and cause other injuries. For example, the most common leukocyte, the granuloqrtic neutrophil, ba been implicated ac the meliator of tissue destructive even~ in a variety of disorde~s, including reperfusion injuIy, rc;.yi~atol~ di~Lrcss syndromes, and pulmonary edema. However? convent;onal 20 cardiotomy reservoirs are not desi~nP~ to remove leuko~ytes from blood before the blood is re~ . cd to the patient.
Accordingly, ~here is a need for i.l.~ruv~,d ~ag filters that avoids the problems wich sewn a~d/or thermally sealed seams. There is also a need for a bag filter that can be used in a cardiotomy reservoir, particularly to r~ ...uv~ undesirable rnaterial 2S such as leuko~tes from blood before ret~iL,g the blood to a p~tiP~lt The present ~.,-cntlon provides for ameliorating at least some of the d,;sadvantagl~s of the prior art ~ese and other advantages of the presenl illvention will be apparent ~om thedescriphon as set forth below.

Summary of th~ Tnven~ion In accordance with the present invention~ a ba~ filter is ~rovi,~ed havi~g an open end and a closed end, wherein the dosed end is formed withollt aIl end se~n Preferably, the bag filter cc,~l"~es a filter e.lçmPnt cu.~ g a polymenc porous n-~Aill~ inrl~-1ittg a cr~ ;nu~ of polymeric m~tY-ial ~Yten~ g fror~ the open end tLougl, the closed end, ~L..ein the f~ter is forrned wilhout a side ~;eam or an end sea~. The fîlter ~an be used to ~lo~ a vane~ of flu3ds, and is ~ 11y useful S for filtenng a biological fluid suc~ as blood or a blood co~ L In an L ..~odi..~e~lL, the bag filter is d;sposed in a de~ce such as a ca~dio~ resen~oir or a drip chamber, and can be used to deplete leukocytes ~om a biologi~l finid.

Brief ~s~ion of ~he DJ~in~,C
Figure 1 is an embotlim~nt of the present ~vention, illustra~ing a cardiotomy 10 reser~oir inr~ in~ a bag filter.
Figure 2 is a s~l~e ~1;c illustration of a~ embo~i~ent of a s~;tem accordi.,g to the present ~nvention, ir~rln~ a cardiotomy resen~oir iIlcluding a bag filter.
Fi~re 3 is a side ~new of a melt-Uo~ung ~pa~ lus sho~ving ll~e translation of a ~oll~cto~ having a cap at one end Figure 4 is an end ~new of a melt-blo~nng ~ppaJa~us with hva rows of angled and offset fiberizing noz~les.
Figure S is a top view of the apparat~ls illustrated i~ Figure 4 as seen along line A-A of F~ re 4.
Figure 6 is another eml~o 1..,.~ ..t of tbe pl.serlt invention, illu~ g a drip 20 chamber in~ g a bag filter.
Figure 7 illustrates a collector a~ld a variety of differellt collector caps tha~
can be used to produce bag filters ill accorda~ce with the invenlion. ~igure 7A
illustrates a collector and one cap. Figures 7B - 7E ilIustrate o~her ,~ollector caps.
Figure 8 is another en h~l;..-ent of the ~)leS~ inventio~ illus~-a~ g a 25 cardiotomy resc~ ,ir in~lnd;~g a bag filter, and further co"",ri~ing a vent including a porous m~ m for passing gas therethrough.

Specific Description of the Invention In accordance with the invention, a filter is pronded COIllpliSi~g a filter medium formed into a bag confi~lration with an oper~ng, an in~ide surface, and an oulside sll-h~e7 s~id filter being free of an end seam on at least one end.
~e pr~e~t invention also provides a f~lter ~.~g a cy~ ical ~lter element co~,~i~ a porous ~e 1;.. , the elemerlr ha~ng a first enld, a second end, and a hollow i..l.., ;or, ~l~eill the second end is closed without an ~nd seam.
S The i~stant in~ention als~ pro~ndes a filter ~ ine a cylin.drical filTer el~m~nt CU~ isil~g a poly~eric porous medium. s~id elem~nt havin.g an open end, a closed cnd, and a hollow interior, wherdn tbe element comprises a col.~inuul.. of polymeric material at the closed end.
Preferably, the filter ~o~lLses a cont;~.. l. of polymeric material e~te~
from the open end thro~lgh the closed end.
Tbe filter, which can be used to filter a varie~ of nuids, especially biologic~lfluids such as blood aDd blood components, is ~pically ~isposed in ~I hous~g.
A filler de~ce according to the inventiûn CUlll~ CS a housing having aIl inlet and an outlet, and del;..;..~ a fluid flow path bet..~e~ the inlet and lhe outlet; a 15 filter ~icpns~1 m the housing across the iluid flow path, the filter co~plisil~g a cylindrical filter clc,l.e.,t cornprising a porous m~ n, ~e ~le~r~ent ha~ing a hrst end, a second end, and a hollow intenûr, ~Lelei~ the second end is closed wilLout an end seam.
The present in~ention also provides a filter device cv ,t,li~ing a housing 20 ha ~ing an inlet and an outlet, and defining a nuid flow path between the inlet and the outlet; a filter Ji~oscd in tbe housing across the fluid flow path., the filter cc,ll.l"is~g a c~lindrical filter element COIllyliS~g a porous m~ m, the el~rnent ha~ing an open end, a closed end, and a hollow interior, wherein the~ elemem comprises a co~.l;.. ~.. of rnate~ial at the closed end.
In accord&~ce ~ith t~e instant invention, a method for filtering a fluid is provided comprising ~assi"g the fluid through a bag filter cu~ i~ a cyli~drical hlter element co.~ ~,~sing a porolls me~ m the eleln~ont ha~ing a first end, a second end, and a hollow inSPrior~ ~vhereiII the second end is closed without an end seam.
The present invention also pro~ndes a ~r ~tho~ for ~,uc~s~;,.g .a biological 9uid COIllpriSi~lg passing a biological fluid conhining undesirable matcrial through a bag filter co~rising a ~I;rlllr;~ dl filter element comprising a porous me~di~ , t~eelement ha~g a first end, a second end, and a hollow interior, wherein tbe second -21 9~654 end is closed ~tll.~ut an end seam, wherein pass~ng the biolo~ical fluid through the filter deplet~s undesirable material ~om the biological fluid.
SyJ~ for filtPrin~ fl~d,s are also provided, wherein the ~,tetILc inc~ p a filter a~eor~ing to the inventio~
S Preferably, filters, de~ices, methods and systems according t~ the present invenuon provide for deple~, leulco~ytes ~om a biolog~cal fluid.
The follo~ definitinns are used in accordance with tbe in~erltion:
(A) Biological Fluid. A biological ~luid includes any treated or untreated fluud ~soci~te~1 unth li~i~ organis~nc, particularly blood, including whole blood, warrn or cold blood, and stored or fresh blood; treated blood, such as blood diluted with at least one phy~iolc~ic?/l solution, inclu~in~ but not limieed to saline, nutrient, alld/or ~nhco~gulant sOlu~ions" blood eo~po~ents, sucb as platPlet co~centrate (PC), platelet-rich plasma (PRP~, platelet-poor plasma (PPP), platelet-~e~ plasma, pl~cm lresh frozen plasma (FFP), cQ~ ..rnts obtained f~om pl~m~ pac~;ed red ceLIs 15 (PRC), tr~nci~iQn zone matenal or buffy coat (BC); blood products denved fromblood or a blood romI~on~nt or derived from bone marrow; red cellls sepd~ted from plasma and rr~ end~ in phys~ological fluid; and platelets separated from plasma and res~cnded in p~iological fluid. The ~iological fiuid may have been treaeed to remove some of ehe leukocytes before being ~ocessed ~ccording to the invention.
20 As used herein, blood product or biological fluid refers to the components described above, and to similar blood products or biological fluids obtained b'r other me~nc and with simila~ properties.
A "unit" is the ~uallLilr of biological fluid ~om a donor or derived f~om one unit of whole blood. It may also refer to the quantity drawn duril~g a smgle 25 donatio~ ~pically, the volume of a unit varies, the amount dirre~"lg from patient to patie~t and from donation to donation. Multiple UNtS of some blood ne~ts~ par~allarly platelets and buff~ coat, may be pooled or combi~ed, ~pically by coTnbinin~ four or more ~its.
(B) Porous Mediu~ The porous medj~m of the bag filter ii a medi~m 30 through ~hich a fluid, ~pically a biological fluid (e.g., blood or at le~t one blood co~ l.t) passes. The porous ~-r~ typically rt~ es one or more undesirable subst~nces from the fluid. For example, t~e porous medium can rer~ove con~p~ nt (i~ bic-l~ic~lly active ~emelltc such as C3a); lipids (in~lu~
lipid elobll~Ps, lipid droplets, and lipid par~ tPs); ~o~l~Psced par~icles; clots; bone fr~..... ....,c r.l~, gels; a~ates; microaggregates; and/or leuko~es frora a biologic~l f~uid.
The porous medium of the bag filter comprLes a fibrous me~ lm Preferably, the porous mPt1i~lm co.~r.~;cPs a fibrous nonwove~ web, :more prefclably a melt~blowr~ fibrous non .. ~ ~., web wherein m~t~ l is filberized b~ extmsion into a high veloa~ gas stream and collected as a mass of mech~ ly ent~nEled or inter~wined fibers. T~e poro~ m~Prliu~n can be multilayered and/or a composite o~
10 dir~e~l materiaL and/or media. The porbus m~ m may also include one or more structures having ~ erenl characteristioe and/or functions. For example, the porous mP.'illm can c~,~p..~e a ~lter pro~iding for leuko~te depletio~, as well as prefiltration and/or micro~regate r~u~L In some embofl;" F"l~, the porous met'illn-7 can also provide for d~;fo~.,.i.,g and/or ven~.
The porous ~di~-n is configLlred as a bag filter. Preferably, the bag hlter lacks an end seam at t}~e closed end, i.e., the end is fo~ned as a cQntiT~ullm of ll.a1e~ witbout joining the matenal by sewing and/or melbn~ the fonned ~terial.
In a more preferred çm~odirnpnt~ the bag filter is formed without a side seam and without an end seam, i.e., the ~ol~lif7L.u~ of material eY1Pn~ls ~om the closed end of 20 the f;lter to inrll7d~ the sides of the filter. ~ illuslrative ~7hotlirnent, wherein the bag filter comprises a cylinrlric~l filter element, ~e co~ uu~ n~ls from theclosed end of the filter to include the cylindrical side ~valls defining the body of the ~Iter lbe filter may include portions or areas wherein fiber-to-fiber bol~;~ is 25 in~eased. For ~Y~mrle, the filter a~ include self-b~n~er~ fibers, e.~'., on the nysLrca~ d/or d~L~ea~, surface of the filter, so ~hat the fiber-t~-fi~er bondingprovides :~U~JU11 and/or drai~age.
The bag filter may co~ ise other structures or layers in addition to the filter materia~, such as an inner linet and outer wTap of a non-woven material such as of 30 polypropylene. The bag filter may include an end ca~. The bag filter may alsoLo~ ise a mesh, screer~ and/or meLub~alle. The additional s~u~ es can provide, for example, ~u~po,l, drainage, ~t,ntillg and/or de~o~..i~.

2 1 ~654 A ~ariety of ~t~lials ca~ be used to produce the porous m.~ of the bsg filter, w~ich ~pic~ally c~plises a polymeric stmcture 1T1 a p~ d e ~od;~
the porous ...~ l;u5.~ CS a leuko~yte depl~tio~ ~I.f~ Suit;able m~t~rli~ls in~lu~e sy~the'dc poly~eric ~ h~iaL such as, fo~ f Y~ple, polybu~lene 5 t~r~thalate (PBT), polyethylerle, polyet~ylene tercph~ te (PEl~, pol~r~ le~c, polymerlrylpentPn~, pol~ylidene fluoride, nylon 6, nylon 66, n~lon 612, nylon 11, and ~ylon 6 copolymers.
In one emboAim~nt the leulco~te depletion ~ Ji~ c~ ~ses a .~.c 1;~
prepared from melt-blown fibers. Illustradvely, U.S. Patent Nos. 4,880,548;
4,925,572; 5,152,905; 5,258,127, and 5,443,743; and International Publication No. ~O
96/03194, dicr]ose leukoc~te depletion media C~JI~fiSil~g melt-blown fibers. The]eukoc~te depletion ~r.l;..", can include a pluralinf of layers.
The porous ...~.1;..,., of the bag filter is preferably treated fo:r inaeased ef~cien~ in proccJ~;r-y~ a biolo~cal fluid. For example, the mediurn may be surface 15 moAifi~.d to affect the critical we~g surfaoe tension (CWST) of the m.o(~ m as descnbed in, for example, U.S. Patent Nos. 4,880,548; 4,925~57~; S,152,905; 5,258,127, and 5,443,743; and Illte~ onal Publicahon I~os. WO 93/04763 an~ WO 96/03194.
Preferably, the porous ~y~rtl~ of the bag filter according to the inven~ion~
which is, more l,referably, a porous synthetic polymeric me~ m, has a C~ST of 20 greater than about 58 dylles/cm. For PYQmpl~., the medium may ha.ve a CWST inthe range from about 60 d~es/crn to a~out 115 dynes/cm, e.g., in lhe range of abo~t 61 to about 100 d~nes/c~ In some e~.bo~1l..,Pnt~ the m.orlinm has a CUtS~
of about 62 dynes/cm, or greater, e.g~ in the range from about 63 to about 70 dynes/cm, or in the range from about 85 d~nes/cm to about 98 dynes/c~
Surface cha~aneristics of the rr~ in~T1 Ca~l be mc~-lifi~d by ch~:rnical reaction including wet or dry ox~dation, by coating or depo~ n~ a polyrner a~n the surf~ce, or by a grafting reactio:lL Grafting reactions may be acti~ated by expo:sure to an energy source such as gas pl~m~q, heat, a Van der Graff generator, ultraviolet light, clç, hu beam, or TO ~arious other forms of radiation, or by surface etching or deposition using a plasma tre~tmPnt, l~ach of the ~O~ n~ntC of the inYention will ~ow be descnbed in more detail below. In the following descriptio~ like co~ ollents have like reference ~ hel~

2~ 98654 dance with the invention, a bag filter co~ ,ses a fi}ter ~ 2t cornpris~ a porous luediul" formed into a bag c~nfi~lration ~ aul open end, an inside s~ , an outside surf~rP, and a dosed end, wherein the filter is free of an end seam at the closed end. T~pically, the bag filter is rli~posed in a ~1Q~ p~
S In the c~ y c .. bo~;-n- ~-t illu~lldted in FlgUre 1, devicc 100 ~o,~piises a honsi~lg 7, having a plurality of inlets 1, and at least one outlet 3, and a baE~ filter 4 disposed across the flu~d flow path between the inlct(s) and the outlet. The bagfilter 4, which is free of an end seam, has an inner sur~ce 11, an outer surface 12, an open end 9, alld a closed end }O. In this illustrated embo~lim~n~ device 100 10 includes a col~ar or sleeve 8 that en~g~s the open end 9 of bag filter 4, and also indudes a retainer 6 tO further secure the bag filter ~n the housing. I~e illustrated device also in~ d~.s a vcnt port ~, as well as a ~rf.~ elernpnt ~ u~hc~l o~ t~e baB filter 4. Optional~y, t~e device in~ s a delivery port 13 (in dotted lines). Ill the exemplary embo~imPnt illustrated ~n Figure 8, the device also inclll~es a vent 19, in fluid c~ u~cation unth an inlet 1, the vent 19 hav~ng a porous structure 21 that allows gas to pass cherethrough. l~pically, the por~ e c~pped or ~o~e~ until thedevice is eo-mect~d to other col~lpolle~ts of a plor~ss;ne s3~stem such as a pump and/or another c~ ~onent of a biological fluid l,r~xes~ tem In an embodi~ent, '~he de~nce 100 comprises a cardiotomy ~ uir for use a biological fluid processin~ system, more preferably, an extracorpor,eal blood treatment system. ~or example, as illustrated in ~igure 2, device 10l) is interposed between a source of biological fluid such as a patiPn~, and a c~ntainer 30 for biological fluid such as a ~enou~7 rese~roir for blood. One or more pressu~e dif~erential generators 70 such as peristsltic pumps pass b]ood ~om the patient to ~5 t~e device 100 along conduits ~1 (e.g, a cardiotomy sucker line) and 62 (e.g., a ventricu1ar ~ent line). The bag filter 4 filters the blood, e.g.7 to remo~e surgical debns and, more p,efe~bly, to deplete the blood of leukoc~tes, and the filtered blood is passed along CQl~r3Llil 63 and collected ~ll c~ irl~ 1 30. Typical~y, at least a pOniOn of the blood is s~bseqaently passed along through an o~ygenator 40 and anarterial f~lter 40 and le~urllcd to ~he patient via co~duitc 64, 65, and 66, respectively.
In the illustrated system, blood may also be passed from the patient to the container 30 along L~ il 67 (e.g., a venous line).

21 98t~54 In a~other ~'f '~ em~;--~r-~l, e.g., ~ i]lu~Lc~ted in Pigure 6, dence 10~
s a drip ~h~ b~, COlllp~ s a kou~;ne 7, having an inlet 1 and an outlet 3, and a bag filter 4 ~ oscd across the fluid flow path b~t.. e~l, the ir~et a~d the outle~
The bag filter 4 ~as an inner surhce 11, an outer surfsce 12, an open end 9, a~d a closed end 10. The filter is ~ee of an end seam, and is preferably also free of a side seam The filter Inay be of any suitable c~nfi~uta~:ion and si~:e. l~pically, it is generally cylilldrical in shape. In one eml e~ the cylindrical shape includes a - taper along at least a portion of the lengtb of ~e filter.
A~ noted above, the filter can be any suitable size. ~lustrati~cly, the filter call have a length of about 1 cm or more. In some embodimcnt~ e length is in the rallge of about 25 cm7 to about ~ meters, or more. Typically, the length of the f~lter ~s in the range of about 1.3 cm to ~bout 75 an In one emborliment, the len~
of ~e filter is ~ the range of ~bout 10 an to about 36 cm Illu~-laliv~ .,. ,t~.~ can be about 1 cm or more, more ~rcft;l~bl~, about 3 cm or more. In some ~mboclimP~ the ~ meter is in the raIlge of about 5 crn to about 200 an. I~ other ~-~bo~ m~nts~ the tli~mpt~pr is greater than about 200 cmTypically, ~hc diamete~ of the ~Iter is in the range of about 4 cm to about 30 cm.
Tne diameter of the filter caD ~e subst~nt~ y ulLir~ along its length 20 Alternatively, pOltiODS of the filter may have different diameters. For eY~ple, as noted above, t~e filter can be t~,.,red along at least a portion of its length.
The f~bers G~n have aDy s~lit~ble average fiber diameter, or a range of suitable fiber dia~neters. Illu~L~a iv~ average fIber diamPt.ors are about 1 ~m, or less, to about 50 ~m, or more. Typically, the average fiber diameters a~e about 1.5 ~m to 25 about 40 I~m.
Illustrative fiber de~sihes are about .05 g/cc to about .4 g/cc ~pically about .~0 g/cc to about 25 g/cc. nlu~liative voids volumes are about 95~ to about 50%,~pically about 90% to about ~5%.
The yoro~ of the filter ~n~djllm of the bag filter may be any desired value.
30 Typically, the bag hlter has a tapered or graded pore s-aucture~ with decreasing pore size ~o~n the inside su~face of the bag filter to the outside surface of the bag filter, w~ich will be in the usual direchon of filtration flow. I~l an embodi~nent, the pore 21 9~654 size dc.~ om the inside surface and appro~rhin~ the outside ~ace, and then lCaSeS at tbe ollt~ sur~oe.
Genetally, in those embo.l;...~ .L~ ~e~eil~ the bag fi~ter has a tapered or graded pore struc~are, the filter has a ~ ,n~ density and/or a di~erent fiber S diallle~er ~long the fluid flow path through the m~liurn, For e~u~le, the fiber diameter can be gleater at the inside surface than at the outside surface Alternatively, or ~ldition~lly, the fiber densit~ can be lesser at the ~side surface than at the~ lt~i~e s~ re I~l some embodi~l,e,.l~, the bag filter has t~o or more elP...~r,~L~ ha~ing difEerent pore s~ructures, or the filter compr~ses a single element provillg t~edi~er~"lt pore structures. I1l some embo~ e-~?s of the invention, palticularly in some of the e .~ ntc ~nvol~nng the proces~in~ of a biological fluid, the taperedor grade pore stmchlre is c~pable of pro~riding for the yr~ t;s~i~e removal of clots a~ld/or bone fragsnents, microaggregates, and leulcocytes, if these m:~terial~ are present in ~e biolo~cal fluid. Illu~Ll.lLi~ely, as the biological fluid passes frorn the ~nside surfaoe of the filter to t~e outside surface, clots, gels and/or larger debris such as bone chips can be removed by the larger pores, leukoc~es can be removed by the smaller pores, and rniaoaggregates ca~ be re~"o~ed by the irltermed~iate size pores.
In an emborlim~ the pore sttucture is initial~y tapered or graded ~s described abo~e, and the pores increase in size at the dowrLtream surface. Su.ch a configuration may provide 5~LPI~O" and/or assist in coalesang bubbles, for example~
In an embo~1imPnt of the invention, the filter m~1ium has a ~ore "open" pore stlucture, e g., a larger pore si~, toward tbe open end of the filter than at the closed end of the filter.
In some applir~tirtnc e.g, ~herein tbe fluid to be filtered cQrlt~inc a greater le~el of lln-lesirable material such as surgical debris, the use of a larger pore size tow~rd the open end of the filter prondes some filtration while re~ ring the potential for an interruption in ~luid flow. Thus, the f;lter provides a type ofautomatic bypass system~ while providing some level of filtration effiaen~.
niustratively, the ~ccumtll~hnn of surgical debris such as bonc chips and dots near the closed end of the filter ca~ L~ell~ fluid flow through the sm~ller pores, alld the level of fluid in the filter can rise. However, the larg,er por~s near ~he open end may offer less reCict~n~p to ~ud flow. Thus, the fluid can pass through the upper portions of the filter, and some undesirable matenal will still be removed~om lhe ~wd.
F.~.~J;...e.-t~ of the bag fil~er can be lLsed with or witho~t a housi~g.
S Typi011y, tbe bag filter is ~ in a ~,o~si~g ha~ring an inlet a~d an outlet a~d defining a fluid flow path btt~en the inlet s~d the outlet, wherei~ the ba~ filter is pos~3 across the fluid flow path. Preferably, the bag filter is disposed in a ~lol~cir~ to pronde "inside/out" ~u~d aOW, i.e., fll~id aOW from the irLide s~ c~ of the bag f~lter to the outside su~face of the filter. However, othel a~angements, e.g., 10 "outside/in" to pro~nde fl~d flow from the outside surface of the bag filter to the i~side surface, rnay also be s~i~able.
Figures 1 and 8 illustrate exemplary embodiment~ of a devic~ 100 compris~ng a hollcinE 7, having at least o~e inlet 1, alld at least one outlet 3, and definin~ a fluid ~ow path behreen the inlets and the o~let. The device 100 also includes a bag 15 filter 4 .li~sGrl across the nuid flow path bet~een the i~lets aIld the ou~let. The bag filter 4 has an inner s~face 11, an outer surface 12, an open end 9 aIld a closed end 10, and is tl osed in the housing to provide "inside/ollt" fluid ~aOW.
Typically, the device 100 irl~lu(lec a structure arranged to eng~age the ~llter.Accordingly, using Figure 1 for rerel~..oe, device ~00 ca~ indude a ~ollar or slee~e 8 20 that allows en~g~ .,.. r~ with the open end 8 of bag filtér 4 For example, the colla~
or sleeve c~ slidably or frictionally engage the open end of the filter. The illusttated de~rice further includes a retainer or he 6 (e g., a retainer strip or an O
r~ng) to further secure the bag filter in the ho~sine In a~other arrangement foreng~ng the filter witb the ho~ (rlot shown)~ the bag f~lter inrludes a collar 25 ~tt~r,he~ thereto, and the collar ~n~gec unth the housing.
In some embo-lim~ntc, particularly those embodiments where;in air (or an~
other ~ype o~ gas) is present, the device m~y a1so prov~de for separating the air or gas ~om the fluid to be iïltere~. For example, the ~eYice may also inelude a vt:nt and/or a defo~min~ element, Al~e~nali~ly, or additionally, the bag filter can 30 prov~de for ve~ting and/or defo~mi~
In an embodiment, particularly in an embo~limeT-t ~vherein device 100 compnses a ~a~diotom~ reservo~r, the device includes a vent and provides for defo~min~. In some emhod;---P~ , the bag filter 4 provides for defo~TriT~ by co~lPs-ing bubbles of air, and the larger bubb]es are ve~ted Of ccurse, the dence can include a separate s~ucture, e.g., a d~fo~ ele~ent, that co:alesces bubbles of air. In the e~ t illustrated in Figure 1, de~ice 100 inc~ s a ~ent port 2 and S a defo,.r-~ , ehment S ]t~tP~1 u~L~ea~ of the bag ~lter 4. In ~e e~ otl;ment ill~slr~ted ~n Figure 8, device 100 jnt~llldes a ~ent 19 including a porous structure 21 that allows gas to pa~.s tb~retll~ough.
In other ~ bG~ rntc (not sho~4n), the device can inc~ e7 f,Dr example, a vent incllltli~ a porous structure, and a ~efo~mi~ element downsbream of the bag10 filter, In otber i~ Lld~ . eull"Dtli...rntc, the de~ce can include a vent includirlg a porous ~ , ~he~ the dev~ce either laclcs a defoaming element, or has defoami~g ele.~.r..~ d dowusLrGam of the bag filter.
A ~ariety of d.r~ iJ~ el~ 5 are suitable for ca~ out the inven~io~, and the elemcnt can be dispnce~i ul~LJeam and/or d~w~e~l of t~e bag filter.
15 AdditionaLly, tbe ~'bfO7~ element can be treated with antifo~miT1~ agents as is kl20wll in the ar~ Sn;takle defo~"Jll~ elll... nlc i~lclude, but are not limited to, those disclosed in U.S. Patent Nos. 4,S72,724 and 5,362,4067 and open cell foams, e~g., polyurethane foa~c7.
The e~bo~ ted ~ Figure 1 i~rludes a plurali~r G~ pOI'tS, i.e., three inlets 1, an outlet 3, a vent 2, as well as an op~on~l delivery port 13 ~dotted lines). I~pically, delive~y port 13 and/or one o~ more inlets 1 sre sealed (e,g, with a cap and/or npe~ e~c connector) when not ill use and/or when th.e device is ~otattached to another e~ nt of a fluid ~loci ss;~ system, Of course, the de~nce can have fe~er ports, or additional ponts" or other ~5 combinations of port ~pes. In some embodiments, ports can have a plurality of functions. For ~mrl~, one of the inlet ports can be used as a deli~ery port, particularly if it is desirable for the rn~teri~l to be delivered, e.g., a lhe~ap~ulic agent, to be filtered by the bag filrer. Alternatively, a delivery port .~an be utili7Pd as a ven~ In another emborlim~nt, an i~let po~ call be used as a vent port. For example, as illustrated in Figure 8, ~n inlet port 1 can be in fluid co~mmur~ication with vent 19.
In yet another embollimens, the device has an additional outlet port, e.g" to provide for collecting filtered blood in a ~ t~ Pr other than a ~enons ~S~f~oll. Of course, the syslem inclu~i~g the device ca~ have ~ddirion~l ports u~ .am and/or dow~L,~am of the devioe as desired. For ~y~mple~ using Figure 2 ~or rcfer~nce, ~e s~stem ca~ de an ~ ihnn~l port dO~ of the devi~e 10D to allow filtered 5 blood to be collected in a cQnt~iner other than the venous resen~oir 30. T~e system (and/or the de~ice) can in~ de one or more addition~l vent ports. In one embo~liment e.g., as illus~ated in ~:igure 8, the device inrllld~s a vent 19 includir~ a porous s~ucture 21 for p~c5;n~ gas tllerctLr~ugh ~n some e ..~ ntc a ~ent port also includes a pl.,s~ul~ relief ~ralve for relie~qng y~s~ u~ ta. of t~e bag filter.

In other i~ 1dti~e, cmbo~ t.. , the device can have two ports. ~or example, using the exempla~y embo~;",~.,t illustrated in ~igure 6 for reference,device 100 can comprise a drip cha~ber, tbe housing 7 including a~l inlet port 1 and an outlet port 3, witb b~g hlter 4 disposed across the fluid flow path ~om the il~let to the outle~
The device lW (e.g., a cardiotomy reser~oir or a drip chamber) ca~ be any suitable con~iguration a:cld size. In some e~bodimeIlts involving a l~ardiotomy reser~oir, the device has a total ca~aaty of several liters or less, ~ically about 3 liters or less. In some e~ho~lim~nts inYol~ing a drip chamber, pa~icularly for those embodiments ~Le,~ei~ the fluid to be processed comprises a biolog~cal flwd, the drip chamber has a total capaci~ of, for example, about 50 cc or less, m.ore ple~,ably about 20 cc or less. Typically, when usin~ a dnp ch~mber to proce~js a biological fluid~ about two-thirds of the total capaci~ of the drip cham~er is used for con~ ing the biol~l fluid, and the rest of the capaci~ is used tO CQnt~;n air or gas.
The bousing 7, that can comprise a plurality o~ portioILc of st:ctions, can be fabricated from any s~lit~bl~ rigid impen~ious rnateriaL ir~ in~ any impervious thermoplastic material, which is col~lydtible ~nth the fluid being pr~cessed. ~or examp]e, t~e housine can be fabricated from a met~L such as stainl~ ss steeL or ~om a polymer. In some embo~ f ~-1C, partiallarly in those embo~ ..t~ invol~ing the 30 procescin~ of a biologiq~l fluid, the housing is a polS~ner, more preferably a t~ e~ll or tr~nsluce~t polymer, such as all acIylic, polypropylenl~, polyslyrene, or -a pol~ o~te~ resin. Such a housing ~s easily aIld econr mi~11y fabr.cated, and allo~s obse~ n of the p~C~,e of the biolo~cal fluid tbrough the h-llcin~.
If desired, the de~ice ca~ ude ~d~lihona1 st~ctures such ~s a saeen, core and/or cage, e.g., for :~U~JOll ar.d/or drainage. In an tlubG~l;.. P~t the device S in~ludes an end cap for ~e open end of tbe bag filter.
In an embotlimerlt, the dev~ce inrlude5 a porous stmcture such as a membrar.e that allows gas to pass th~through, e.g., from the iIlterior of the houslng through the membrane ar.d the vent. For ~Y~mE~le~ the porous struttwe can ~Il.p..se a .iquophobic membrane tha~ a.lows gas, bu~ not biologica~ to pass 10 the,~lh[uugh. If desired, the bag filter ~ ~ in~lude the membrane (,e.g., ~s part of c~ e)-In the e.nho.3;..~l.L Dlustrated in Figure 8, the device ~ncludes a ~ent 19incll~di~ a porous structure 21 that allows gas to pass therethrough. In some of t~e emborliments wherein the porous stmcture Z1 cu.,.l.. ;ces at least orle me~ra~, more preferably a liquophobic membrane, the porous structure 21 ple~ t~ the passage of b~ n~ therethrough. For eY~pl~, the porous structure can have a pore rating of about 2 ,um or less. Ill an embodiment, the pore ratillg can be abou~
.02 ~m. Suitable vents and porous structures inrlude~ but are not lil~ited to, tbose lnsed in U.S. Patent ~os. 5,126,0S4, 5,451,~21, and 5,362,406.
AlternatIvcly, or additionally, at least a portion of the bag filter 4 itself (e.g., withou~ an sdriitisn~l structure or e1~rnent) passes gas without p~cin~ biological ~uid therethrough. For ~Y~mI~le, at le~st a por~ion of the bag ~lter 4 (e.g., a ~and nearer the opell end of the filter than the closed e~d, ot any des~red area of the ~lter) can have a lo~ver Critical Wett~ng Surface Tension (CWSI') ~lan the ot~erportions of the bag filter. In these embo-limen~s, gas, but little o~ no biological fluid, passes through the ponions that have the lower CWST. If desired, Ihe bag filter can be treated to provide portions ha~ di~cr~llt CWSTs. For e~ample, portions of the bag filter can be surface mo~l;fi~d to change the CWST of one or ~ore desired portions, without modi~ing (or providing less mo~1ifir~tion to) the CWST o~ other desired portions.
Ill acco~da~ce with a preferr~d embc~ -t of the in~ention, a filter rnPAi~lm ha~ing a closed end is produced by forIr~ing the medium in a tubul;~ configuration 2 1 ~8654 onto a rotating mandrel or c~ nr. For e~lc, as ~ at~d iD. Figures 3 a~d 4, hbers can be mclt-blown onto a cc~ or 200 (which is ~rer~.~bly ~enerally drica~ i~ shape) while the collecto~ is rot~ , and tr~n~l~ffne with the fibers o~jle~1 on tbe surface of the collectnt ~d on one end of the collector.
~igure 3 ill~sLIat~s the tr~n~l~hQn of the collector 200 with re~.~ to a fiberizer assembly 302.
One ~ od of ~r~,pa~ g a melt-blow~ fibrous ~O~ J~ 1 web comprises cxtrudiIIg molten resin from two parallel rows of lillea~ , s~bst~n~i~1lyequally spaced ,.u~lcs to fonn fibers onto the sl~rh~e of a collector ~a~qng a 10 lcm~itu~lin~ as a~la~ed parallel to the rows of nt~ s, wl-e~ the rows of nn77les are ofE~et from each other a~d are angled toward each other. Figures 4 and S iIlus~ate one ~'Y~ P1~ A- l~ g, ~-lf ~-1 of Tln773eC 300 on a m~nifold 301.
~ he rows of nozles can be off~iet ~om each other by, for ex;~rnple, about one-half the spacing between The nozzles withi~ each row and the row~ of nozles 15 are preferably angled toward each otber by sll~st~n~ y equal but opposite angles, e.g, each of the rows of nc~ 5 ~s anglet by about 40~ or less, more preferably, about 25~ or less, from a vertical plumb line r~n~in~tin~ at the center of the co]lector.
Other suit~hle Trletho~ls for yl~y~ a melt-blowsl fibrous nonwoven w~
20 include using a single row of nozzles, and/or a~ymmetrically arranged nozzles. The n~7.les m~y be arranged to prov~de crossed st~eam fibers or non-crossed stream fibers. FY~rnP1~1Y methods for preparin~ melt-blown no~l~u.~IL we~s in~ll]~ but are not limited to thQce clicrl ~se~l in U S. Patent ~loc 4,726,901 and 4,5514,20~, and International Publication WO 96/~3194.
2~ The co]l~çtor 200 G~ have any suitable ~ mpTer~ and the dis~meter can be substantially ~cmct~nt alollg the length of the collenor. Typically, the diameter is about 2 cm or more, more preferably about 4 cm or more. In some embor3impnt~
tbe diameter is about S cm to about ~00 tm e.g, about 10 cm to 150 cr~L In o~er embo lim~nt~, the diameter may be greater thall about 200 cm, or abo~t 1 crn, for 30 example.
In acco~dasce vv~th the invention, the collector ca~ have, for example, a ~h~n~e~ne diameter along at least a por~on of its length. Illu~ ively, the colleaor can in~lvde a diameter that genera~ de~l~ases along a poniOn of the le~gth, or generally de~ases froln one end of t~e colledor to the other. Fi~ure 7A illustrates a collector that Gm be used in ~cco~d~ce with the invention, ha~irlg a t~red m~t~r over a porbon of its length.
S One end of the ç~ ctor 200 can be confieured to ~r~l~lce a desiredcharacteristic or feature for a closed end of the bag filter. For example, the end of the collPctQr can be ~er~d to produce a less rollnrw end for the filter.
Alte,~au~ely, tbe end o~ the ~cllector can be inverted to produce, for ~Y~m~]e~ a filter end hav~ng a des~ed density. In some embo~ (.t~, the collector 200 has a G~p 201 to pro~de the desired filter end cbar~enstic or fearure.
Of cou~e, the c~ ctor can be used ~uth a variey of di~crc~ t caps having difr~re~lt shapes for a desired resul~ Figures 7A ~ 7E illu~l~al~ a few of the chapes of ca,~s 201 that ca~ be uced in accordance vvith the invention. ~igures 7A - 7Dillustrate caps ha~ng angles of 90~, 60~, 60~, and 30~, respecti~ely, I igure 7Billus~ates a cap having a stepped shape, and Fig~e 7E illustrates a cap ha~g a d~led shape.
While a cap ~01 having any angle can be used i~ accold~ce with the invention, one l"~fe,~ed angle ~s in the range of ~om about 4~~ to ;lbout 90" Insome emboflim~ntc, using a lesser augle than about 90~ (e.g., about 65~ or less)prondes a medium having a more uniforrn vveight along the cross-section of the me-lmm litiQll~lly~ the cQllf ~tor 200 can be hollow, ~it~ one or mc~re holes in the end andlor sides. ~e cap 201 can aLso have one or more holes therethrough. Such cor~igurations may be usefu~ d~g vanouS stages of producing and h~n~llinE the 25 filter mediu~ Illu~Ll~tivel~l, in some r~l.o~1;~ntc ~lle,e~n ~he ~ol1ector has one or more holes in ~e end nd/or sides, a ~os~u~ve ~,L~ e can be created within the in~enor of the coll~ctor for ease in rc~u~ing the formed bag filter fi~om the coll~ctor. In other e~bo~ cnts, a negative ~l~ssurc can be createcl within the inter~or of the collector ~rhile forming the bag ~lter to more effiaently coIltrol the densi~ of tbe bag medium The collector (which can be bollow or solid) may be surfaced w~th a sui~able release co~hng ~1 '18h54 The collec~or ca~ be rotated at any suitable surface ~elocit~, gcnerally at le~st about 20 m/min7 and pl~erably not ~ n~ about 1000 m/mi~ I~ an ~ ..bo~lim~nt, the s~rface velocity is i,n the raIlge from a out 150 m/'rn~n to about ~!50 m/mllL
S The collF~tor 200 is p~erer~bly tr~ncl~A at a rate not exceeding about 2 crn/revolu~o~ ID one illu~LraSi~ embo~ e~.! the t~anslation rate does not e~ceedabout 1 all/revol~lhon Ihe nn771~ can be spaced any suitable ~ist~nr~ from t~e co~lector, yrefe~bly about 2 cm to sbout 50 cm, more preferably about 2 cm to about 25 c~ II1 generaLthe die-to-~ or ~lics~nce (DCD), which s the distance from the nozzk ~ip to the surfaoe of the collector, is ~m~ller when a filter ~edil~n of higher density with lower voidls volume and highcr tensile all~L is desired. ~ desir~d, mnl~ passes can be rnade, typically while a Ij~l~g the DCD and/or the fiber ~ m~ter~ tO produce a bag f;lter with the desired charactenstics Within each of tbe rows, the ~o77l~s can be spaced apar~ any s7lit~1e distance~ gener~lly about 2 cm or less. In an illusLrdlive em~o~ime-lt the sp2cebet~-veen the n~771es is about l cm or less. T~e parallel row~ ca31 b~: spaced apart any suutable fiist~nc~e, plefclabl~ such that the nozzle tip to nozzle ap separation b~ cll rows is about I to 2 cm 1~OIC~Y~I~ in a preferred embo~im~nt, the web is prepared ~hile a ~cgduYe ~r~ e is m~int~inpd between the rows of the nozles.
Illustratively, a negative pressure in the range from zero to about 4" of water colu~Ln can be generated within the nozzle m~nif~ l 301 to produce a more uniform produc~
The bag filter according to the present u~rention can be used ~n any ~ltering ploto~ol, eJ~e~;~lly those invol~nng co~ nl;nn~l bag filters. l~or example, the bag filter can be used to filter paints and c~ ngS, especially ~ater-baset~ paints and primers, r~m~ s~ petro~ mic~l products, ~rater, and aq~eous susple~sions.
In some embo~ ..e~-Lc of the inventio~, the inventive bag filter is used to filter a biolo~pcal fluid. ~or ~ le, the bag filter can be used in a drip rh~ber to 30 remove dots, microaggregates and leuko~tes f~om a biological fluid. In a morepreferred embo~1i...rnt the bag filter is ~sed to deplete surgica~ de~ris and leuko~es ~om a biological ~uid.

2~ ~8654 ~ , method for us~g the bag filter to filter biological fluid can be des~bed ~vith ll f~r~l.ce to Figures 1, 2, and 8. Figures 1 and 8 ill~Lstrate exempla~y o~1i...~l.t~ of device 100 in~lu~ine a bag filter 4 ~ordil,g to the in~ention, and Figure 2 illustrates a sy~tem fo~ filtering a biological fluid irl ~n extraco,y~r~,al S ~alit ~lsing the device ~00.
D~g surgery, a biolog~cal fluid such as blood is removed fi om the cavi~ of tbe patient and delivered to the device 100 (som~times r~:r~rled to 'belo~ as the "cardiotomy rese~oir") via the ~entncu1ar vent line and the cardiotomy sucker line(s). In some embo~im~ntc~ at least two cardiotomy sucker lines a~e utilized.10 Blood passes throu~h inle~ fo~.,.;..e el~nl~nt 5, a~d bag filter ~. As the fl~ud passes Illr~)ugl~ the filter, t~e. ~luid is depleted of undesirable material such as lipids (e.g., lipid ~1obules) ~d/or surgical deb~is (e.g., aggregates, bone c]hips alld/o~
clots). In a pr~,fell~d embo~ ont~ the fh~id is also depleted of leuko~es. In one illu~Llali~- embc~ ncnt, the biological fluid is depleted of about 90% of the 15 leukogtes or more. In so~e e~ im~nt~, the biological fll~id is depleted of about 99~0 of the leu~.~es or more, even about 99.9% of the leukocytes or more.
Additionally, since air ~s typically present in the cardiotomy reser~o~ 100 (e.g., due to the delive~y of foamy fluid to the device), the a~ is vellted from the resenoir through vent port 2. Generally, the defo~g element S acts to coalesce ~0 bubbles of air, and tbe coalesced bubbles are vented Ihrough vent port 2. As no~ed earlier, defo~mi~ elements can be disposed upstre~m aIld/or downsrream of the bag filter 4, Aller~l~ti~ely, or ~ lition~lly, the bag fi~ter 4 ç~ sces b~bbles. Thus, in some e~ho~ wherein cardiotomy rese~voir 100 laclcs at least one defo~min,~
25 e]~rnent 5~ the bag filter 4 pr~des for ~o~les~ n~ the bubbles, whi~:h are vented through vent port ~.
In some embo~ c~ls, e.g., wherein the bag filter 4 also inc]udes a liquophobic membrane and/or one or more portions with lower C~STs, the air (but little or no biolo~cal fluid) pass~s through the membra~e a~d/or the lower CWST
30 portion(s).
Ill some embo~ , e.g., vlr~th or ~nthout orle or more de~'o~lnin~ elements, some of the air can be vented without ~assll,g it through tbe bag filter 4 For el~mrl~, using the exempla~y device 100 illustrated in Figure 8 for le~e~c~ce, some of the air en~n~ t~e device 100 passes out of the device through porous structu~e 21 and vent ~9. without p~c~c;.~ thro~lgh the bag filter ~.
In some embodi.l~P~-t~ e.g., wher~ device is ut~ ed as a cardiotomy S resen~oi~, the di~re~-Lial p~css~ across the dence preferably is about 15 p.s.i or less. In more ~lcft.led embodime.ntc invol~ring a cardioto~y reservoir, the dir~e~e~-~ial ~ ; is about 10 p.s i. or less, e~en more preferably, about 6 p.s.i. or less.
In the illus~ c embo~l;... ~.t sho~ in ~igure Z, the hltered blood passing through cardiotomy rese,~o~ 100 is co1lected in a C~ ii.f Y 30 such as a venouS
rese,~,c,i[. Tgpic~y, ~t least a por~on of this blood is re~med to t~le patient na the arterial line (e.g., after pa~7~7~llg through an o~ygenator 50 ~nd an art~nal filter 40).
Hu~ r, in some cmbo~imPnt~ (not sho~vn), at least a por~ion of filtered blood is passed ~om the cardiotomy resel~oi~ 100 to a cont~iner otller than c~ t;.;.. or 30, or the fluid is pacsed to another container dow~7t~ea~ of c,ont~in~r 30.
ati~_ly, it may be desirable to further process the biological fl~lid before relurn-~g it to the patient. For example, in some embodiments w~e~eirl the biological fluid is a red blood cell cont~ fluid, ~e red blood ce].ls can be saline washed, and the washed cells can be returned to the patient at the ~atient7s ~edside, ~0 e.g., after the patient has been rlicc~nnect~ from the extraco~poreal! circuit ill7~trated in Figure 2.
Other embodiments ind~ding a device in~lu~ing a bag fil~er ;~re encompassed by the invention. Por PY~mrl~, in one embo~iment, e g., as illustratl~d in Figure 6, device 100 co~ ses a drip chamber. In some embo~limP-nt~ e.g., ~rherein the fluid 2S p~c~inE into ~he device conlpnses a biological fluid? the biological fllud p~sin~
th~o~gh the bag filter 4 can be depleted of undesirable materi~l, if the material is present in the fluid. E~or example, in some el~diL"cnts, the biological fluid passing through the bag filter is depleted of lipids, clots and/or microaggregates.
Alternatively, or ~ on~lly, the biological fluid pass~ng through the filter is 30 depleted of leu~cocytes.
Further embodiments are en<~Tr~rqYed by the invention. For example, in one emb~ the bag filter produced as des~ibed above is subsequently 2i ~654 mo~lif;~l, for e~ lo, by se~ing and/or heat se~li~e. Addiliol~ally or all.,~udti~_ly, tlhe open end of the bag filter can be closed, or a filter ean be pro~ that is dosed at bo~h ends without an end seam at either end. In other embodim~nts, the bag filter call be produced as described above a~d subsequently pl~ated along at5 least a portion of its length, or the fibers can be melt-blown onto a coll~octor shaped to provide a bag filter that is pleated along at least part of its lengtlh ~xam~les r.. ~,~?le 1.
The bag filter used in this ~y~mple is ~ red as follo~s. lrwo i~berizers, 10 each with a row of nh~ s~ are offset alcially of each other by 038 ~,m, and are an~led toward eacb other at an inrlin~tion of 13~ ~om the vertical. The two sets of inter~ecting f~er alIe~Lus deliver polybutSlene terephth~l~te (hereinafter PBT) res~
on a ~lindrical collector.
The col]ector is 17.8 cm in length (i~r1ur7ing the cap), and h~ a tapered 5 ~ m~tçr over a portion of its length ~e diameter ranges from 6.4 cm nea~ the cap, to 8.4 an at ~e other end of the collector. A cap uith a 90~ angle is used. Rele~ase paper is placed over the length of the collector.
The collectDr is rotated at B80 rpm while it is ~ t7~nloQvcly tr~n~l~t~1 a~ially at the rate of .5 cm per revolution for the length of each pass or stroke. The 20 stroke, which is 114 cm, is lon~er than the length of the collector. I~ibers are deposite~ on the surface of the collector, ;n~lutli~ the capped end of the collector.
The collector is operated for 6 passes, and the PBT resin thr~ughput Lhrough the nozzles is kept çss~ti~lly cQ~ t Fhe resin te~eralur~" and ~e air te~ re are each about 650~F (about 346~C). The resin is deli~ered at the rate o~ 1~6 grams per mi~ute per nozzle The air pr~ssu~e through the fibeli~;i.,g nozzles is changed before each of the first 5 passes to provide a different fiber tii~m~t~r for each of the Slrst S layers of the filter. Ibe air ~ .ure is e~nti~l1y the same for passes 5 and 6, and thlls, ~he fiber diameter provided durin~ passes S and 6 is essent~ y the same.
The air pressure for t:he s~lccesshe passes is 15 p s.i., 18 p.s.i., 25 p.s.i., 32 p.s i, 39 p s i, and 39 p.si The a /erage fiber diameter for che succ,~ssive passes is 10 ~r4 5 ~m, 4 ~m, 2~ ~rn, 2 ~ur4 and ~ ~
T'ne die-to~ll~or distallce (l~CD) is ~aried from 2.4 cm for the first pass tO
1 cm for the lasl pass while mAint~;~.;.,e an e ~,ch1.~lly uuif~l~ density of .13 g/cc for eac~ layer.
S The bag filter thus produced is removed ~om t~e collector. The filter. which is formed without an end seam and without a side seam, is gas pla~;ma treated topro~qde a cr~tical ~.etLi~g s~rface tension (C~WST) of about 67 dynes/cm T~c bagfilter ~s fl~Yiblc, and the closed end of t_e filter is in~rerted slightly, e.g., ~y ptlchi~
against the du~ ca~l sur~ce of-the end of the filter to form a fl:~ttened end, 10 before plaang ~e filter in a llollcin~
Ihe treated bag filter is placed in a CO~ eial~ available ~rdiotomy reservoir hol~sing after the c~"~.n~r.ially a~ilable cardiotomy filter (an~ ~Pf.~ r) is removed ~e h.3 -~;.,,~ in~ es a~l open ve~t pon a vent port w,ith a pressu~e relief valve, three inlet ports, and an outlet port l'he f~ n~d encl of t~e filter 15 conlacts a small ~,~oje~lion on the i~ner surf~oe of the hous~g.
Appr~m~tely 1 liter of blood is passed through the device at a flow rate of about 500 cc/rnin The ~ er~nlial ~re~u,~ does not exceed 6 p.s,i. A compar~son Of influe~t and cffln~n~ leukocyte counts shows that the blood is dq~leted of at least 99% of the leul~ocytes.

20 Exam~le 2.
A bag filter is produced as described in Example 1. The clolied end of the filter is inverted as descn~ed above, The treated bag f;lter is placed in a com~nercially available ~ardiotomy reser~oir housirlg after tbe çnmmercially available cardiotomy filter (arld d~fo~ f r) 25 is ~emoved, The nattened end of the filter coutacts a small proje.LiDn on the inner surface of the housing.
The housing inrl~ldes an open vent port, a Yent port wich a pressure relief val~e, three inlet ports, and an out~et port.
A ~vc~Li~, de~ice ~~ ising a housing having an inlet and aDi outlet and a 30 liquopbobic membrane having a diameter of 2S mm disposed across the ~uid flowpath 1~eL~ .. the ~ent h~ ing ir~let and outlet is provided. ~he membrane, which is produced ~n &c:ordd~ ~th ~J.S. Patent ~o. 5,451,321, h~s a pore ~ating of abo~t 2 ~m or less. The ~ 1;~, dence is placed in fluid co~ ;~h~ln ~ith one of the ~r~ou;l~ J r~3_~c~,i inlet por~ ss gcnerally ill~Llated in ~ e 8.
Al,p~ tely 1 liter of blood is passed ~rough d~c device at a flow rate of S about 500 cc/min. lhe ~ re,ltial yress~ is less than 3 p.si. A Co~ ;cnn of infln~ nt and effluf nt leuko~e coullts sho~rs lhat the blood is .lepleted of at least 99% of the lel~kocytes.

~ of the l~f~ nc~6 dted herei~, in~ p7u~lir~tion~ p~knt~ and patent applic~hnn~, are hereby i~ JOf~t~l in ~eir ent~reties by reference.
While tbe in~endon has been descnbed i~ some detail b~ W.ly of illus~ation and e. ~ ~?e, it sbould be ~ Lood that the in~entiorl is s~scepti~le to various modifications and al~divc forms, and is not restri~ted to the spe~fic emho~ set for~. It should be ~d~ ood t~at these specific embo-limenLs are not int~nded to limit tbe invention b~ on tbe co~ , the int~nsio~ is to cover alJ
1~ mo~iifi~tions~ eql~rvalents, and al~ es f~lling within the spint .~d scope of the enhon.

Claims (28)

1. A filter comprising a cylindrical filter element comprising a porous medium, said element having a first end, a second end, and a hollow interior, wherein the second end is closed without an end seam.

2. A filter comprising a filter medium formed into a bag configuration with an opening, an inside surface, and outside surface, said filter being free of an end seam on at least one end.

3. A filter comprising a cylindrical filter element comprising a polymeric porous medium, said element having an open end, a closed end, and a hollow interior, wherein the element comprises a continuum of polymeric material at the closed end.

4. A filter comprising a cylindrical filter element comprising a polymeric porous medium, said element having an open end, a closed end, and a hollow interior, wherein the closed end is formed from a continuum of polymeric material.

5. A filter comprising a cylindrical filter element comprising a polymeric porous medium, said element having an open end, a closed end, and a hollow interior, wherein the element comprises a continuum of polymeric material extending from open end through the closed end.

6. A filter device comprising:
a housing having an inlet and an outlet, and defining a fluid flow path between the inlet and the outlet;
a filter disposed in the housing across the fluid flow path, said filter comprising a cylindrical filter element comprising a porous medium, said elementhas a first end, a second end, and a hollow interior, wherein the second end is closed without an end seam.

7. A filter device comprising:
a housing having an inlet and an outlet, and defining a fluid flow path between the inlet and the outlet;
a filter disposed in the housing across the fluid flow path, said filter comprising a cylindrical filter element comprising a porous medium, said elementhaving an open end, a closed end, and a hollow interior, wherein the element comprises a continuum of material at the closed end.

8. A method for filtering a fluid comprising:
passing the fluid through a bag filter comprising a cylindrical filter element comprising a porous medium, said element having a first end, a second end, and ahollow interior, wherein the second end is closed without an end seam.

9. A method for processing a biological fluid comprising:
passing a biological fluid containing undesirable material through a bag filter comprising a cylindrical filter element comprising a porous medium said element having a first end, a second end, and a hollow interior, wherein the second end is closed without an end seam, wherein passing the biological fluid through the filter depletes undesirable material from the biological fluid.

10. The method of claim 9, wherein depleting undesirable material from the biological fluid includes depleting leukocytes from the biological fluid.

11. The method of claim 9 or 10, wherein passing the biological fluid through the bag filter comprises passing the biological fluid through a cardiotomy device including the bag filter.

12. The method of claim 9 or 10, wherein passing the biological fluid through the bag filter comprises passing the biological fluid through a drip chamber including the bag filter.

13. The filter of any one of claims 14, being free of a side seam.

14. The filter of claim 1, wherein the second end is conically shaped.

15. The filter of claim 1, wherein the first end is open.

16. The filter of claim 1, further comprising an end cap sealing the first end of the filter.

17. The filter of any one of claims 1-4, and 13, wherein the filter medium comprises a melt-blown fibrous medium.

18. The filter of any one of Claims 1-4, or 17, comprising a leukocyte depletionfilter.

19. The device of claim 6 or 7, comprising a drip chamber.

20. The device of claim 6 or 7, comprising a cardiotomy reservoir.

21. The device of claim 20, wherein the housing further comprises at least one additional inlet, and a vent.

22. The device of claim 20, further comprising a vent including a membrane for passing air therethrough.

23 A filter device comprising the filter of any one of claims 1-5, or 13-15, disposed in a housing, the housing having an inlet and an outlet, and defining a fluid flow path between the inlet and the outlet, wherein the filter is disposed in the housing across the fluid flow path.

24. A method for filtering a fluid comprising passing the fluid through the filter of any one of claims 1-5.

25. The method of claim 8, wherein the element lacks a side seam.

26. The method of claim 11, including venting air from the cardiotomy reservoir.

27. The method of claim 26, including venting air through a liquophobic membrane.

28. The method of any one of claims 9-11, 26, and 27, wherein depleting undesirable material from the biological fluid includes depleting lipids from the biological fluid.