United States Patent 1191.
[11]
Rosenberg
[45] Oct. 16, 1973
[54]
DUAL BLOOD FILTER
2,914,181
.
,
333,32
N.Y.
3,701,433
[751 111mm Dav-d J- Rosenberg, Glen Cove,
,
11/1959
3,765,537
Naftulus et a1. .................. .. 210/446
.................... ..
0 44
if}??? 322?; .......... .. 15812132‘:
10/1972
Krakauer",................... .. 210/446 X
[73] Assignee: Pall Corporation, Glen Cove, NY.
.
.
Primary Examiner—-Samih N. Zaharna
[22] Flled'
July 31’ 1972
[21] Appl. No.: 276,623
Assistant Examiner-Richard W. Burks
Attorney-John R. Janes
Related US. Application Data
[63]
Continuation-impart of Ser. No. 38,356, Nov. 10,
1970, P t. N . 3,
l,
3,
'
'
[57]
-' -
of Ser_ 130 223,532, 33w ilgfilaggmmuanon m part
ABSTRACT
.
.
,
.
A disposable ?lter element is provlded, capable of
passmg human blood at _a high flow rate and useful 1n
human blood transfusion systems, to remove unde
éil """"""""" " 210/446’ zlo/étisdlzdlgggg
sired suspended particles, substantially without re.
[58] Field of Search .................. .. 128/214 B, 214 c;
m°val.‘?f “91ml mid ‘les‘rable bl°°d c°mp°nems’
2lO/446 493 499 505 507
compnsmg 1n comb1nat1on two ?lter elements, the
'
[561
"
’
’
’
?rst comprising plastic netting and having a pore size
References Cited
UNITED STATES PATENTS
$31?
3331121323 2311252253,?!’ $331,021,351;
mesh having a pore size within the range from about
1
2,473,153
2,571,059
5/1949
10/1951
Lager ............................ .. 128/214 C‘
Puschelberg et a1 .......... .. 210/507 X
2,644,586
7/1952
Cutter ....................... .. 128/214 C X
25
20 to about 50 microns,
32 Claims, 6 Drawing Figures
/ it 8 E“ I‘
27
12
, '
‘
.
22
a
24
23.
_
20
SEE FIG. 3
36
15
'1
_
gm
‘i
'
__
,. /
,3
3
21
25
3,765,537
_ 1
DUAL BLOOD FILTER
This application is a continuation-in-part of Ser. No.
88,356, ?led Nov. 10, 1970, now U.S. Pat. No.
3701433 granted Nov. 21, 1972, and Serial No.
263,584, ?led June 16, 1972.
There are in general two types of blood ?lter avail
able on the market for use in human blood transfusions.
The most common type is made of wire mesh, or nylon
2
oxygenator was ?ltered, a pressure gradient was built
up across the ?lter, necessitating a switch to another
?lter hooked up in parallel to the ?rst; and also air was
trapped in the ?lter during initial ?lling, and was found
to be possibly ejected later, directly into the arterial
line. The blood reached a very low level of blood plate
lets within the ?rst 10 minutes of use of the ?lter, and
this condition persisted during the entire period of by
pass. There was also a drop in white blood cells, and the
or polyester ?lament mesh, having a pore size within 10 decrease in both was much more pronounced than usu
the range from about 125 to about 140 microns (Surgi
ally seen in heart-lung bypass, showing that the ?lter
cal Advances, V0. 11, No. 6, September, 1951). These
caught huge amounts of platelets and, to a lesser ex
?lters are referred to as blood strainers. They are very
tent, white cells. The pressure gradient built up across
coarse in pore size, because they have a strong ten
the ?lter was in part attribued to this mass of cells, and
dency to block quickly if the pore size is any finer.
in part to intravascular coagulation with formation of
The other type of blood ?lter useful in transfusions
is a rather thick nonwoven ?brous mat, usually of poly
caught on the ?lter tended to disintegrate subse
ester ?bers, and referred to as a Dacron wool ?lter.
quently, and the disintegration products entered the fil
?brin trapped in the ?lter. Moreover, the platelets
This ?lter is the subject of U.S. Pat. No. 3,448,041 tp
tered blood.
R. L. Swank, issued June 3, 1969, The ?lters available 20 The invention of Ser. No. 88,356, ?led Nov. 10,
commercially have a pore size up to several hundred
1970, provides a disposable ?lter element comprising
microns, and are prepared of very ?ne ?bers.
The principle upon which the Swank ?lter is based is
described in the patent at column 3, starting at line 51
a woven square-weave plastic mesh of polyester mono
?laments having a pore size within the range from
about 25 to about 50 microns, the ?laments being
and continuing through column 4, line 36. Swank 25 locked in place at their crossing points, and the fila
wanted a ?nely subdivided material having surface
ments having a diameter within the range from about
25 to about 50 microns. Such ?lter elements are capa~
characteristics and a size such that it selectively col
lects the storage-altered components of blood used in
ble of removing microemboli from human blood in
blood transfusions. The filter is intended to act as a
human blood circulation systems that require circula
base to which the adhesive storage-altered platelets and 30 tion of the blood at a high ?ow rate without removal of
leucocytes adhere. Free passage of the other blood
normal and desirable blood components. The ?lter re
components is supposed to be permitted by the ?lter,
moves not only microemboli but also lipids and debris
which has a large area of absorbing surface, to achieve
and gas emboli, and it also has a low resistance at high
a high capacity with a minimum apparatus size. Swank
?ow rates and at a high flow‘ capacity, and does not
also wanted a material which could be used over long 35 tend to block over long periods of use.
operating periods without collapse or plugging, and
without being affected adversely by repeated subjec
However, for use in blood transfusion, this ?lter is
not fully satisfactory. Blood for use in transfusions has
tion to heat and chemical sterilization.
The problem of blood strainers is that they do not re
a tendency to contain blood clots, a condition not nor
mally encountered in human blood circulation systems,
move enough of the small ?nely-divided material, be 40 which utilize the blood of the patient in the circulation
cause of their large pore size. On the other hand, the
system. Blood clots are sticky masses of material, and
nonwoven ?brous mat ?lters are at the other extreme.
if large numbers of blood clots are present, the woven
square weave plastic mesh can block very quickly.
these ?lters remove too much material, and also have
In accordance with the invention, a dual blood ?lter
a very high tendency to block. Large numbers of plate 45 element is provided which can be used in blood transfu
lets and white blood cells and bodies of like size in the
sions without blockage, and which is capable of remov
Despite their large pore size, in excess of 100 microns,
blood tend to be strained out, leading to rapid blocking,
ing not only large particles, such as blood clots, but also
and a compression of the mat under the increased fluid
smaller particles, down to approximately 2044. in size,
pressure differential thereacross. Both of these effects
while passing red blood cells and at least a substantial
50
are undesirable. These results are reported by Egeblad,
proportion of white blood cells. The blood ?lter cas
Osborn, Burns, Hill and Gerbode, The Journal of Tho
cade of the invention comprises two ?lter sheets, ar
racic and Cardiovascular Surgery, Vol. 63, No. 3,
ranged in downstream ?ow sequence in order of pro
March, 1972, pp. 384-390; and by McNamara, Burran
gressively increasing ?neness, i.e. from coarsest to ?n
and Suehiro in a paper entitled “Effective Filtration of
est in pore size.
‘
Banked Blood,” (a copy of this paper is in the ?le of 55 The ?rst ?lter sheet is coarse open netting of plastic
U.S. application Ser. No. 88,356, ?led Nov. 10, 1970).
Egeblad et al. report that they had good results using
the Dacron wool ?lter during perfusion for open-heart
?lamentary material having a pore size within the range
from about 800 to about 4,000 microns. This pore size
is ‘small enough to remove blood clots which range
surgery, where the ?lter was placed in the line between
from
500 to 1,000 microns in diameter, and it is coarse
60
the cardiotomy reservoir an the main venous line, in
enough to do so without being subject to blocking by
which position a large proportion of the circulating
the blood clots that are strained out.
blood system bypasses the ?lter. Such a system requires
The second ?lter sheet is an open- or square-weave
a much higher rate of flow of blood per unit of time
mesh fabric of plastic mono?laments, having a pore
than a blood transfusion system, so that the results ob
size within the range from about 20 to about 50 mi
tained represent results similar to those obtained in
crons. This ?lter sheet removes microemboli, lipids and
blood transfusion, but in a shorter time. When placed
debris, and gas emboli, virtually all of the particles that
in the arterial line, so that all blood coming from the
pass through the ?rst ?lter element except platelets,
3,765,537
3
4
white blood cells, red blood cells, and other like ?ne
particles.
7
The ehtylene glycol-terephthalic acid polyester
'
mono?laments are preferred because of their availabil
This combination of ?lter sheets can be referred to
as a cascade, because each succeeding ?lter sheet in
the line of flow removes some of the particles passed by
the next-preceding ?lter sheet. The relative proportion
ity and low cost. However, polyesters of other glycols
and acids can be used.
Exemplary polyester mono?lament screen cloths
which can be employed as ?lter sheets in accordance
of particles removed by the individual ?lter sheets of
with the invention are made from polyester mono?la
this ?lter cascade is remarkably distributed between
ment 20, 25 and 40 microns in diameter with (a) a
mesh opening of 53 microns with 33 percent open area,
(b) a mesh opening of 44 microns with 27 percent open
area, (0) a mesh opening of 37 microns with 23 percent
open area, and (d) a mesh opening of 21 microns with
both filter sheets, so that neither ?lter sheet has a ten
decny to block over a given blood transfusion to a sin
gle patient. For sanitary reasons, blood transfusion ?l
ters are not reused, even for the same patient, if a sec
ond transfusion is administered at a later time; and
since the ?lter element cascades of the invention are
fully disposable, their use resolves the blocking prob
14.5 percent open area. Similar screen cloths are avail
15
able, made of polyamide ?laments, polyvinylidene
chloride ?laments, and polypropylene ?laments.
lem common to blood ?lters which are ?ne enough to
remove small particles such as the adhesive nonviable
It is also preferred that the mono?laments of the
woven square-weave mesh be locked in position at
The ?rst ?lter sheet has an open-mesh netting struc
their points of crossing. The locking not only increases
strength and rigidity, but it also ?xes the pores against
change in dimensions in use, which is extremely impor
platelets.
ture. It is prepared by extruding, casting, or molding 20
plastic into an open-netting having an integral ?lamen
tary structure.
The plastic material used is compatible with blood.
Exemplary are polypropylene, polyethylene, polyester,
polyamide, and polycarbonate.
One form corresponds to an open square-weave
woven ?lamentary netting, even though it is not manu
factured by weaving techniques from ?lamentary mate
rial. An extruded open-mesh plastic ?lamentary poly
propylene sheet is available commercially under the
trademark “Vexar.”
'
tant.
The dual ?lter sheet cascade of the invention can be
?tted into disposable ?lter elements of any design and
con?guration. For maximum open area and high flow
25 rate in a con?ned space the two ?lter sheets are prefer
ably assembled in close juxtaposition, although they
can also be separated by spacers, and both are prefera
bly corrugated or convoluted, to provide a high surface
area to flow, together with any spacers present.
The spacer or support material is stiffer than the ?lter
sheets, and is preferably ?exible, and also preferably of
Other forms of netting are available which do not
plastic, so that it can be bonded to the same end cap in
correspond to an open square-weave fabric. In these,
a ?lter element or to the ?lter bag. The spacer has a
the ?lamentary plastic material can be arranged in a
pore size at least as large as the ?rst ?lter sheet, and
manner to de?ne round, elliptical, or polygonal open 35 preferably larger, within the range from about 800 to
ings, which can, for example, be triangular, square,
rectangular, pentagonal, hexagonal, heptagonal, and
octagonal, singly or in pattern combinations. One de
about 10,000 microns.
I
As the spacer, any sheet having an uneven surface,
such as dimpled, ridged, or quilted, and with large
openings therethrough, can be used. Extruded, cast and
plastic ?lamentary material and arranged in groups of 40 molded netting are useful, as also are perforated sheets,
sign, for example, has triangular openings separated by
six to form a hexagonal pattern, and another has trian
of polypropylene, polyethylene, polyester, polycarbon
gular openings arranged in groups of two to form a dia
ate, and polyamide. The surface of the spacer or sup
mond. The shape of the open pores in the netting is in
port is suf?ciently uneven so as to provide drainage and
no way critical, but it is important that the pore size be
prevent blocking of the medium and ?ne ?ler sheets by
within the range from about‘ 800 to about 4,000 mi 45 the support sheet. A preferred supporting material is
crons, the pore being measured across the largest and
Vexar mesh (extruded polypropylene netting).
the smallest dimensions, if it is other than round or
The spacers can also assist in retaining the ?lter sheet
symmetrical such as square.
cascade in a desired shape, such as particularly a corru
The second ?lter sheet is a woven open-mesh square
gated shape. The spacer if present is usually in close
weave fabric which can be made of any plastic mono?l
juxtaposition to or in contact with the second ?lter
ament compatible with blood, such as polypropylene,
sheet of the cascade. No spacer sheet need precede or
polyethylene, polyester, polyamide, and polycarbon
follow the ?rst ?lter sheet of open netting, bcause of its
ate, and has a pore size within the range from about 20
large pore size.
I
to about 50 microns. The mono?laments have a diame
A suitable con?guration of ?lter element has the ?l
ter within the range from about 20 to about 50 microns.
ter sheets folded into a corrugated cylinder, the open
Polyester mono?laments are preferred. Most polyes~
ends of which are closed off by end caps, limiting ac
ter mono?laments available are polyesters of ethylene
cess to the ?ltrate ?ow line to flow through the ?lter
glycol and terephthalic acid available under the trade
mark “Dacron.” Polyester mono?laments can also be
cascade, the ?ltrate ?ow line being in operative con~
nection to at least one of the end caps. The end caps
made of other polymers of alkylene glycols and dicar 60 are preferably of plastic material and can, for example,
boxylic acids, usually aromatic acids, but also cycloali
phatic and aliphatic acids, of which propylene glycol
l,2, butylene glycol-2,3 and -l ,2, and pentylene glycol
l,2 and -2,3 and -l ,3 are exemplary, esteri?ed with ter
be of polyester or polypropylene or polycarbonate. The
end caps can be bonded to the corrugated ?lter sheet
cascade using a potting compound or an adhesive of
conventional type. However, to ensure a leak-tight seal,
ephthalic acid or alkyl-substituted terephthalic acids, 65 it is preferred to fuse the end caps to the ?lter sheet
or adipic or subaric acids, or cyclohexane-l,4—
dicarboxylic acid.
cascade, and for this purpose a polyole?n, such as poly
ethylene or polypropylene, is preferred as the end cap
5
3,765,537
material. Othe plastic materials that can be used as the
end caps include polyamides, polycarbonates, and
polyester, as well as Te?on polytetra?uoroethylene and
Kel-ef polytrifuorochloroethylene, but these are more
dif?cult to bond.
Another suitable form of ?lter element has the ?lter
sheet cascade and spacer sheets in corrugated form en
cased in a plastic bag across the line of ?ow between
the inlet and the outlet of the bag, which can, for exam
ple, be in the form of line connections such as tubes
opening onto opposite sides of the ?lter sheet cascade.
This type is especially useful for attachment to blood
transfusion bags, and can be provided with a piercing
tube connection for this purpose, if desired.
The cascade ?lter element of the invention can be 15
used in ?lter units intended for simple blood transfu
6
each side a pair of locating ?ngers 15, and portion 3 has
on each side two pairs of locating ?ngers 16, with a slot
17 therebetween into which ?ngers 15 ?t. These locate
the portions 2, 3 on assembly. Sides 12, 13 at their ends
abut sides 9, 10, and are fused thereto, so that the hous
ing portions are bonded together as one piece. A pair
of projecting members 20, 21 on portion 3 extend par
allel to and internally of sides 12, 13 all the way to the
internal wall of housing portion 2.
The two-component ?lter sheet cascade and spacer
composite 40 at each edge 22, 23 projects into the
sockets 24, 25 de?ned by sides 12, 13 and members 20,
21, and where the three sheet-composite curves around
the tips of members 20, 21, it is held tightly at 26, 27
against the internal wall of portion 2 and is bonded
thereto.
The bond is produced by fused integration of the
member 20, 21 to the housing portion 2 through the
desired. The cascade ?lter element can accordingly be
open pores of the two-?lter sheets 41, 42 and the
provided with ?ttings or line connections suitable to 20 spacer 44 forming a ?uid-tight seal at 26, 27 all along
adapt it for in-line connection in blood transfusion sys
those sides of the composite, and bonding all three
sion where high ?ow rates are not encountered, as in
drip or gravity ?ow from blood bags, pump-assisted, if
tems of any type.
Preferred embodiments of the invention are illus
tained, for example, by ultrasonic welding, by solvent
trated in the drawings, in which:
softening, or by heat fusion.
sheets together at those points. Such a bond can be ob
FIG. 1 represents a side view, in section, of a ?lter el~ 25 The ?lter sheet cascade and spacer composite 40,
ement in box form including a dual-?lter cascade, in
best seen in FIG. 3, is composed at a ?rst coarse ?lter
accordance with the invention;
FIG. 2 represents another side view, partly in section,
of the ?lter element of FIG. 1, showing the side caps on
the ?lter housing;
sheet 41 of extruded polypropylene netting (Vexar),
FIG. 4 represents an isometric view of an embodi
and 27 percent open area. The weft mono?laments and
pore size about 1500 microns. The spacer 44 is also
made of extruded polypropylene netting (Vexar), of
30 the same pore size, about 1,500 microns. The second
FIG. 3 represents a view in detail of a portion in sec
filter sheet 42 is made of open-mesh square-weave
tion shown in FIG. 1 of the ?lter sheet cascade of the
polyester mono?lament fabric having a pore opening of
40 microns, a mono?lament ‘diameter of 40 microns
invention;
ment of ?ler element in bag form including a dual ?lter 35 the wrap mono?laments are backed together by heat
cascade in accordance with the invention;
setting at their points of crossing de?ning ?xed 40
FIG. 5 represents a longitudinal section of the ?lter
micron pores at their interstices.
element of FIG. 4, taken along the line 5-5 and look
The two filter sheets 41, 42 of the ?lter cascade are
ing in the direction of the arrows; and
in corrugated form, for an increased surface area in the
FIG. 6 represents a cross-section of the ?lter element 40 limited space of ?uid chamber 4, and the tips of the
of FIG. 4, taken along the lines 6-6, and looking in the
corrugations abut and are held in place by the project
direction of the arrows.
ing sections 8 and 11 of the housing portions 2 and 3.
The ?lter element of FIGS. 1 through 3 is composed ' The edges 32, 33 of the ?lter sheet cascade run right
of a housing 1 having ?rst and second housing portions
to the ends of the sides 12 and 13.
2 and 3 defining a fluid chamber 4 therewithin. A ?uid 45 The housing channel portions 2 and 3 are open at
port 5 is at the base of housing channel portion 2, and
their sides and, as best seen in FIG. 2, de?ne openings
a ?uid port 6 is at the base of housing portion 3. It will
28, 29 leading into the ?uid chamber 4 of the housing
be seen that these ports are coaxial. The port 5 serves
1. The openings are closed off by side caps 30, 31
as a ?uid inlet, and the port 6 as a ?uid outlet, and ?ow
which are bonded to the housing portions 2 and 3 and
is only in the direction from port 5 to port 6, because
also to the edges 32 and 33 of the ?lter sheet cascade
of the arrangement of the two ?lter sheets in the cas
and spacer composite 40, extending along the openings
cade, as will be seen.
from end to end between the mating sections 9, 10, 12
The inlet port 5 is housed in a spiked tube 7 which
and 13 of the housing portions. This closes off the other
is designed to pierce a blood bag stopper for use in
two side edges of the ?lter sheet cascade to ?uid ?ow,
55
blood transfusion. Housing portion 2 has an internal
and restricts flow between the two portions 34, >35 of
projection or rib 8, extending from one side 9 to the
?uid chamber 4 in the housing via the pores in each of
other side 10, and housing portion 3 has a like internal
the ?lter sheets in the ?lter sheet cascade 40. Thus, all
projection 11 extending from one side 12 to the other
?ow between ?uid ports 5 and 6 of housing 1 must pass
side 13. These serve as supports extending across the
through each of the two ?lter sheets in the direction 41,
corrugations of the three-component ?lter sheet cas
42 as is evident from FIG. 3.
cade and spacer composite 40, serving as the ?lter.
The assembly of the box ?lter element of FIGS. 1 to
Each housing portion 2 and 3 is generally channel
3 is as follows. It will be seen on reference to FIG. 1
shaped, with opposed sides 9 and 10 extending out
that the sides sections 9, 10 12 and 13 of each housing
wardly from the base of portion 2, and opposed sides 65 portion 2, 3 have a special construction which ensures
12 and 13 extending outwardly from the base portion
a ?uid-tight seal between the housing portions when
3. The bases of housing portions 2 and 3 are each pro
they are bonded together. ‘The opposed sides 9, 10 of
vided with ?uid ?ow channels 14. Portion 2 has on
housing portion 2 meet and abut like sides 12, 13 of the
3,765,537
8
exactly as shown in FIG. 3, with the ?lter sheet 41 out
other housing portion 3. Portion 2 has one pair of each
ermost and spacer 44 innermost in the closed con?gu
side of side-locating ?ngers l5, and portion 3 has two
ration shown in FIGS. 4 to 6. The corrugated shingled
pair on each side of side-locating ?ners 16, receiving
composite 60 is heat-sealed at 52 along its four sides
?ngers l5 therebetween to ensure that the portions ?t
snugly together in the correct position to hold the ?lter
(or along three sides, if folded on itself). The thus
enclosed ?lter sheet cascade 60 has an outlet line con
sheet cascade 40 in place.
nection via the tube 53 extending into its open interior
The sides 9, 10, 12 and 13 are each slightly longer
space 54, and terminating in a caged tip 55. The only
than their combined length after they are bonded
inlet into the interior space 54 is via the ?lter sheet cas
togher. When portions 2 and 3 are ?tted together, the
sides 9, 10 are readily fused to sides l2, l3, respec 10 cade 60. This type of ?lter element is especially useful
tively, to produce an integral one-piece structure at the
in a ?exible bag-type of ?lter unit, the bag 56 being
shown in dashed lines in FIGS. 4 and 5. The other end
seal 36, FIGS. 1 and 2. Internally of the sides 12, 13 in
of the bag 56 which can be the blood bag itself can have
housing portion 3 are the projecting members 20, 21
an inlet tube 57, for reception of blood. It is also possi
which extend all the way to the interior wall at 26, 27
15 ble to have a spiked inlet tub 57 onto the outside of
of the housing portion 2.
composite 60 in bag 56, in which case it can be heat
In assembly, the edges 22, 23 of the corrugated ?lter
sealed to the bag 56 in the same manner as to the ?lter
sheet cascade and spacer composite 40 are folded
element. This assembly can then be plugged into a
around the projecting members 20, 21 of housing por
blood bag, as in the case of the ?lter element of FIGS.
tion 3 into the sockets 24, 25 between sides 12, 13 and
the projecting members 20, 21, where they are held se 20 1 and 2, with ?lter sheet 41 outermost and spacer 44
curely. Housng portion 2 is then ?tter over the portion
innermost.
The type of ?lter element shown in FIGS. 4 to 6 is es»
3, and presed down smartly against the ?lter sheet cas
cade and combined spacers, pinching the three sheets
pecially useful for transfusion blood ?ltration, in which
at 26, 27 against the tips of projecting members 20, 21,
and holding the three sheets ?rmly in place by the tight
case it can be built into a standard blood bag, but it can
25 also be attached to any type of blood storage reservoir
engagement between the inner wall of the housing por
tion 2 and the ends of the members 20, 21. The project
or receptacle.
The corrugated con?guration of the filter sheet cas
ing members 20, 21 are then integrated through the
cade in this element provides high surface area, and the
shingled arrangement of the corrugation makes it possi
pores of the spacer 44 and the two ?lter elements 41,
42 at 26, 27 to the wall of the housing portion 2, form 30 ble to provide a ?at pouch without the need for a core
support, because the spaces between the shingles act as
ing a ?uid-tight seal therebetween, and closing off both
conduits while at the same time the shingled overlap
sides of the ?lter sheet cascade to ?uid ?ow. The sides
ping structure provides structural support. The support
9, 10 of housing portion 2 can also be bonded to the
or spacer sheet 44 of the two-?lter cascade is of heat
sides 12, 13 of the housing portion 3 by fusion, such as
by ultrasonic welding, at the same time or thereafter, 35 softenable material, which softens at a lower tempera
ture than any of the two-?lter sheets composing the
so that the two housing portions 2, 3 are sealed to
gether, preventing fluid leakage to the outside of the
cascade, so that the ?lter sheets 41, 42 are not affected
?lter assembly.
under the conditions at which the spacers soften, so
that the latter can be fused together in a leak-tight heat
Next, the side caps 30, 31 are bonded across the
opening 28, 29 into the housing portions 2, 3 and to the
?lter sheet cascade and spacer composite edges 32, 33,
40
seal through the ?lter sheet pores without deleteriously
affectng the ?lter sheets. The heat seal is easily effected
by high frequency heat, and all heat seals can be
formed simultaneously, including the heat seals with
bonding the ?lter sheet sides and spacers to the side
caps, and completing the ?xing of the ?lter sheet cas
the tubes.
cade and spacer 40 in place in the ?uid chamber 4, as
well as the seals between the ?lter sheet cascade and 45 Having regard to the foregoing disclosures, the fol
lowing is claimed as the inventive and patentable em
the four side walls of the housing. This can be done us
bodiments thereof:
ing, for example, an adhesive, or a melt of adhesive or
1. A blood ?lter element cascade which can be used
resin or other potting composition, or by fusing the end
in blood transfusions without blockage, and which is
caps. The ?lter element is now complete, and ready for
50
The ?lter element is operated in line, as follows. The
spiked tip is plunged into the stopper of a blood bag,
capable of removing large particles, such as blood
clots, and also small particles down to approximately
20p. in size, while passing platelets, red blood cells and
thereby permitting blood to ?ow from the bag through
at least a substantial proportion of white blood cells,
use.
comprising in combination, two ?lter sheets, arranged
chamber portion 34. The blood then ?ows through the 55 in downstream ?ow sequence in order of progressively
the inlet port 5 and enter the channel 14 ?owing into
increasing ?neness;
?lter sheet cascade 40 via ?lter sheet 41, ?lter sheet 42
and spacer 44, and enters the chamber portion 35,
whence it emerges via channel 14 from the housing via
port 6.
'
Line connections can be made at ports 5, 6 in any de
sired manner. Luer locks also can be used, if desired.
The ?lter, element 50 of FIGS. 4 to 6 has as the ?lter
a composite 60 of a two component ?lter sheet cascade
(sheets 41, 42 and spacer sheet 44) in corrugated shin
gled form, with corrugated folds 51 lying in the plane
of the ?lter element in overlapping fashion. The two ?l
ter sheets 41, 42 and separating spacer 44 are arranged
a. the ?rst ?lter sheet comprising coarse open netting
of plastic ?lamentary material having a pore size
60
within the range from about 800 to about 4,000 mi
crons, small enough to remove blood clots, and
coarse enough to do so without being subject to
blocking by the blood clots that are strained out,
and
b. the second ?lter sheet comprising an open mesh
fabric of plastic mono?laments, having a pore size
within the range from about 20 to about 50 mi
crons, capable of removing microemboli, lipids and
3,765,537
9
debris, and gas emboli, that pass through the ?rst
?lter element while passing platelets, white blood
cells, and red blood cells.
2. A blood ?lter element cascade according to claim
1, in which the ?rst ?lter sheet is an open-mesh netting
10
from the ?ltrate-?ow side of the ?lter element to the
outlet.
18. A disposable blood ?lter unit according to claim
11, in which the housing is composed at least of first
and second generally channel-shaped housing portions,
prepared by extruding, casting, or molding plastic and
having an integral ?lamentary structure.
sides, the ?rst and second housing portions having op
3. A blood ?lter element cascade according to claim
posed sides, with mating sections abutting and bonded
2, in which the plastic material is selected from poly
propylene, polyethylene, polyester, polyamide, and
polycarbonate.
de?ning therebetween a ?uid chamber open at two
in a ?uid-tight seal to each other, and the blood ?lter
10 element cascade in sheet form extending across the
?uid chamber, across the line of ?uid ?ow between the -
4. A blood ?lter element cascade according to claim
?uid ports and held at opposed side portions to at least
one of the ?rst and second housing portions, and side
1, in which the second ?lter sheet is a woven sequare
caps bonded to the ?rst and second housing portions in
weave mesh of plastic mono?laments having a pore size
within the range from about 20 to about 50 microns, 15 a ?uid-tight seal across the open sides of the ?uid
chamber and to the sides of the blood ?lter element
the ?laments being locked in place at their crossing
points.
cascade extending along such open sides, the side caps
and the housing portions holding the sides of the blood
5. A blood ?lter element cascade in accordance with
?lter element cascade, positioning the blood ?lter ele
claim 4, in which the mono?laments have a diameter
within the range from about 25 to about 50 microns. 20 ment cascade across the ?uid chamber, and sealing all
the sides of the blood filter element cascade to the
6. A blood ?lter element cascade in accordance with
housing, so that the ?uid ?ow between the ?uid ports
claim 4, in which the plastic mono?laments are of poly
must pass through the blood ?lter element cascade.
ester plastic.
19. A disposable blood ?lter unit in accordance with
7. A blood ?lter element cascade in accordance with
25 claim 18, having four sides, two of the sides being de
claim 1, in which the ?laments are heat set to lock them
?ned by the side caps and two of the sides by the first
in place.
and second housing portions, and the blood ?lter ele
8. A blood ?lter element cascade according to claim
ment
cascade is in four-sided sheet form.
1, in which the two ?lter sheets are in close juxtaposi
tion, and corrugated or convoluted to provide a high 30 20. A disposable blood ?lter unit in accordance with
claim 19, in which the blood ?lter element cascade is
surface area to ?ow.
in
four-sided corrugated sheet form.
9. A blood ?lter element cascade according to claim
21. A disposable blood ?lter unit in accordance with
8, in which second ?lter sheet is juxtaposed to a spacer
claim 18, in which the first and the second housing por
having a pore size at least as large as the ?rst ?lter
sheet, and within the range from about 800 to about 35 tions and the ?uid ports therein are arranged so that the
?uid ports are coaxial.
Y
>
10,000 microns.
10. A blood ?lter element cascade according to claim
9, in which the spacer has an uneven surface so as to
provide drainage and prevent blocking of the ?lter
22. A disposable blood ?lter unit in accordance with
claim 18, in which all of the housing portions are of
plastic material.
23. A disposable blood ?lter unit in accordance with
claim 22, in which the plastic material is a thermoplas
l l. A disposable blood filter unit comprising a blood
tic resin.
filter element cascade according to claim 1, and a hous
24. A disposable blood ?lter unit in accordance with
ing having an inlet and an outlet and line connections
claim
23, in which the thermoplastic resin is polypro
thereat for ?uid ?ow into and out from the housing, the
pylene.
blood ?lter element cascade being disposed in the 45 25. A disposable blood ?lter unit in accordance with
housing across the line of flow therebetween so that
claim 22, in which the housing portions are integrated
?uid ?ow therebetween must pass through the ?lter el
together to form a one-piece housing.
ement cascade.
26. A disposable blood ?lter unit in accordance with
12. A disposable blood filter unit in accordance with
claim 18, in which the blood ?lter element cascade is
50
claim 11, in which the blood ?lter element cascade is
held at opposed side portions between the mating sec
sheet by the spacer.
in the form of a cylinder, and one line connection has
a direction ?uid ?ow connection to the interior of the
?lter cylinder.
tions of the ?rst and second housing portions.
‘
27. A disposable blood ?lter unit in accordance with
claim 26, in which the blood ?lter element cascade is
13. A disposable ?lter unit in accordance with claim
integrated to the mating sections by fusion thereof
11, having a housing made in two portions bonded to 55 through the pores of the blood ?lter element cascade.
gether.
_
14. A disposable ?lter unit in accordance with claim
13, made of plastic, with the portions fused together
28. A disposable blood ?lter unit in accordance with
claim 18, in which the side caps are integrated to the
housing portions to form an integral one-piece ?lter
unit.
15. A disposable ?lter unit in accordance with claim 60 29. A disposable blood ?lter unit in accordance with
14, including line connection integral with the housing.
claim 18, in which each of the housing portions in
16. A disposable ?lter unit in accordance with claim
cludes at least one projecting portion engaging and sup
14, having the ?lter unit bonded to one housing por
porting opposite sides of the blood ?lter element cas
tion.
cade, and extending with the blood ?lter element cas
17. A disposable ?lter unit in accordance with claim 65 cade across the ?uid chamber.
16, having the ?lter unit bonded to one housing portion
30. A disposable blood ?lter unit in accordance with
at the outlet with a direct fluid ?ow line connection
claim 18, in which one housing portion comprises a
into one piece.
3,765,537
12
11
projecting member holding the opposite end portions
tending internally of the two abutting portions, and en
of the blood ?lter element cascade against the other
gaging the blood ?lter element cascade at a portion
near its edge.
32. A disposable blood ?lter unit in accordance with
housing portion.
31. A disposable blood ?lter unit in accordance with
claim 30, in which the mating sections of each housing
portion have ?rst projecting members extending to
wards each other, and abutting endwise, with the first
housing portion having second projecting members ex
claim 30, in which the second projecting members also
hold the blood ?lter element cascade tightly against an
internal wall of the second housing portion.
*
20
25
30
35
45
50
55
65
*
'll
*
*
Dedication
3,765,537.—David J. Rosenberg, Glen Cove, NY. DUAL BLOOD FILTER. Pa
tent dated Oct. 16, 1973. Dedication ?led Dec. 31, 1981, by the assign
ee, Pall Corp.
Hereby dedicates t0 the Public claims 1 through 17 of said patent.
[O?icial Gazette November I, 1983.]
‘822$? .
M
‘UNITED STATEs-‘BATENTIoFFiCE
J
CERTIFICATE '- OF *CORRECTIGN " '
Patent M
3,765,537
Invv'entor(s)
David J' Rosenberg
15
v
191117
'
Dated October 16,1973” _
1-1?
It is certified that error appears in the above-‘~ideritified patent‘
and that said Letters Patent are hereby corrected as shown below:
Goes page, line 8 '7 "
:
"Ser. No. 38,356H should be -— Ser. No.
“f”
88,355 ~-_
Column 1, line 19
:‘
Column 1, line 6-1
v '
~>
C‘ "attribu-ed" should bé "attributed -
Column 3, lines-'9 and ‘10:
Column 5, lit-1e
.
"an" should be —- and —-_'-f;
,
- Column 4, line 44'
--
"tp" should be -- lo —— .
-
Column 2,l1mé_1_1_;_ v‘
_
"tend'ecny" should be "fendency -
:
"filerf' should be -- ?lter ~
' :
"dzhe" should be —- Other —
Column 6, line 17
:
"n-merrlber" should be --_ members —
Colurhn 6, line 26
:
"at'_' ‘should be -é of --
Column 6; line 63 -_
2
"sides" should be —- side
:
"pair" should be -- pairs-"v:
:
"finers" should be -- ?nger,s_~-- '
: .
"togher" should be," together -
1'
"Housng" should be" Housing." , }
: ’
"presed" should be -- pressed -—
Column-‘7, line 3 1 '
Column 7, line
Y ‘I
\ Column 7, line 9'.-
‘c?lumn 7, line 21 _
Column 7, line 22" -
.
I
a
"'"i
'
_‘
H
2-478 CIP
Eo-wso
'
'
(owe)
f
UNITED STATES PATENT OFFICE:
-
-
H
CERTIFICATE OF CORRECTEQN
Patient: No.
1L»
‘ ’ ' '
-
.4‘
3,765,537_
Dated
October 15, 1973
I
v
>
-Page‘* 2
Inventor(s) S
David J- Rosenberg
It is certified that error appears‘ in the above-identified ‘patent V
and that said Letters Patent are hereby corrected ‘as shown‘ below;
r“
,
‘
I
‘
'
'
-
Y
>
'1
Column 8, hne'15'
, :
"tub" should be -- tube --
Column 8, line-29 v
' :
"corrugation" should be -— corrugations —-v
Column 8, line_.41
Column 9,
'
claim 4,
Column 9,
7
' :
"affectng" should be — affecting _-
_:
"sequare" shouldbe ._-—4squar'e -
1
"direction" should be -— direct —
i
line ‘13 .
_
-
claim '12,
line ‘52'
7
--
Column 9, claim 15,
' lineI-GZ
,
_
-
i
>
.
V
v: '' "connection" should be -'_-‘c_onnections —
Signed and sealed ehis 18th'dsy of February 1975.
(SEAL)
Argest’.
;,> RUTH c. MASON:
Attesting Officer
1-
'
'
-
c. MARSHALL DANN
,
‘ Commissioner of Patents‘
and Trademarks
.1
‘