Blood diluting method and apparatus

An apparatus for diluting packed red blood cells contained in a transfusion bag is provided comprising a flexible, squeezable diluent bag for containing a diluent for diluting the red blood cells in the transfusion bag. A tubular assembly with one or more fittings is provided for permanently attaching the diluent bag to an input port of the transfusion bag. The fittings are adapted for preventing a non-destructive, non-removable separation of the two bags. A uni-directional flow fluid valve means is provided for preventing reverse fluid flow from the transfusion bag to the diluent bag.

BACKGROUND OF THE INVENTION 
The present invention relates to methods and apparatus for collecting, 
processing and transfusing blood in general and, in particular, to a novel 
method and apparatus for diluting packed red blood cells contained in a 
transfusion bag. 
Transfusion bags containing packed red blood cells are obtained in the 
first step of conventional blood processing in which whole blood obtained 
from a donor is separated into its component parts. 
A principal physical characteristic of packed red blood cells which gives 
rise to the present invention and which is evident during normal 
transfusions is their high viscosity and corresponding relatively low flow 
rate in comparison to the flow rate obtained with whole blood. 
Whether the low flow rate in a normal transfusion of packed red blood cells 
is acceptable depends on the nature or character of the therapeutic 
application or procedure involved. In cases of emergency injuries and 
operations involving trauma and high volume blood loss, low flow rates are 
generally unacceptable. In these cases, the packed red blood cells must be 
diluted or whole blood must be used. 
At the present time, using conventional methods and apparatus, the dilution 
of packed red blood cells is time-consuming and troublesome. Quite 
frequently, it is wasteful of diluent used for diluting the packed red 
blood cells. It may also be dangerous to a patient if the diluent used is 
incorrect in amount or type, as may occur in the excitement of an 
emergency or operation involving high volume blood loss. 
On the other hand, the use of whole blood simply to avoid the time and 
trouble of diluting packed red blood cells, when only the extra 
oxygen-carrying capacity of the red blood cells is required, has long been 
recognized by medical authorities as being wasteful of the non-required 
blood components. The use of whole blood when it is necessary only for 
high flow rates is also recognized as being potentially dangerous to a 
patient, as will be further explained below. 
The time and trouble encountered by a physician and the potential danger to 
a patient and loss of supplies using conventional methods and apparatus 
for diluting packed red blood cells may be made more clear by means of a 
simple and brief description of conventional blood collecting, processing 
and transfusing techniques and apparatus. 
Conventionally, whole blood is received from a donor in a relatively small 
plastic bag having a volume of about 500 cc. In preparation for receiving 
the whole blood, the bag, commonly called a primary bag, is filled with a 
small quantity of an anti-coagulent. 
Coupled to the primary bag by means of a plurality of hollow tubes, there 
is provided a number of satellite bags. The primary and satellite bags are 
interconnected by the tubes in such a manner that no air is admitted to 
the bags and the component parts of the blood in the course of the blood 
processing can be transferred from one bag to another with no potential 
hazard from bacterial contamination. This was not possible in the past 
when blood was collected, processed and transfused using glass bottles. 
In the past, any penetration of the blood containers, as by a needle or the 
like inserted through the rubber stoppers used for closing the bottles 
created the potential hazard of bacterial contamination. This resulted in 
a requirement that the potentially contaminated blood components be used 
within twenty-four hours. The twenty-four hour restriction insured that a 
patient's normal biological immunities could handle the bacterial 
contamination if it occurred. 
In the first step of the processing of whole blood into its component 
parts, a primary bag filled with whole blood and its satellites are placed 
in a centrifuge. After a predetermined time at a predetermined RPM, the 
red blood cells and plasma in the whole blood are separated. Thereafter, 
about 200 cc of the plasma is transferred from the primary bag to a first 
one of the satellite bags. The other satellite bags are used for the 
subsequent separation of additional blood components from the plasma, but 
forming no part of the present invention, the steps involved need not be 
further explained for an understanding of the present invention. It need 
only to be understood that the other components are very important for 
blood component therapy and can be obtained only from existing quantities 
of whole blood. 
After the removal of the 200 cc of plasma from the primary bag, the primary 
bag is sealed, as by thermal bonding techniques, and separated from the 
satellite bags for storage in a refrigerator until the red blood cells 
contained therein are required for a transfusion. At this point, and for 
obvious reasons, most persons handling the primary bag now call it a 
transfusion bag. With the plasma removed, the red blood cells are much 
closer together and, being without their normal supporting medium, plasma, 
become "packed," hence the designation, packed red blood cells. 
Having considered how the packed red blood cells are obtained, 
consideration may now be given to how they are diluted using conventional 
methods and apparatus. 
When a physician orders packed red blood cells for a transfusion and there 
is a possibility that a high-volume, high-flow-rate transfusion may be 
required, an appropriate diluent will normally also be ordered. The orders 
are generally directed to a local in-house blood service. Alternatively, 
the blood service may provide the red blood cells while the diluent is 
obtained from a supply of various types of diluents stored close at hand. 
This is possible since typical diluents are simply isotonic or slightly 
hypotonic saline solutions and do not require special storage facilities. 
Regardless of the source of the diluent, most facilities heretofore stored 
and supplied the diluent in large, 500-1000 cc glass bottles. 
In practice, if the diluting of packed red blood cells is required, a 
physician typically suspends the diluent bottle from a first rack or 
hanger and a unit or transfusion bag of packed red blood from another rack 
or hanger. A tube is then inserted in the diluent bottle and in a port of 
the transfusion bag. Generally the tube is provided with a needle or the 
like at one or both of its ends as a fitting to effect the coupling. To 
prevent reverse flow from the transfusion bag to the diluent bag, the 
transfusion bag is usually maintained at a position below the diluent 
bottle. 
As may be recalled from the foregoing discussion, the amount of plasma 
removed from the transfusion bag is typically 200 cc. Accordingly, in the 
course of diluting the packed red blood cells, it is necessary for the 
physician to carefully control the amount of diluent used to return the 
packed red blood cells to the concentration present in whole blood. Since 
the gravity flow is not usually very turbulent, it is also frequently 
necessary for the physician or an attendant to agitate the transfusion bag 
to mix the packed red blood cells and diluent homogeneously. 
In many non-emergency cases and in particular in the case of an emergency 
or an operation involving high-volume blood loss, it can be seen that the 
time it takes to dilute a transfusion bag, the care that must be exercised 
to insure that only the proper amount of diluent is added to the bag and 
the trouble that is involved in having to agitate the bag all tend to make 
the diluting of packed red blood cells, using conventional methods and 
diluent bottles, unacceptable. It should also be noted that, unless all of 
the diluent is used once a diluent bottle has been penetrated, the 
remaining diluent must be discarded. This is because, as previously 
discussed, any penetration of a blood or diluent container creates a 
potential hazard for bacterial contamination requiring that the components 
and diluent be used immediately. 
Another problem with conventional diluting methods and apparatus is that 
the availability of various types of diluents in the same type of 
container can give rise, and has not infrequently given rise, in the 
excitement of an emergency or the like, to the inadvertent use of the 
wrong diluent. 
For the foregoing reasons, and becasue the attending physician is the 
person who is ultimately responsible for the proper dilution and 
administration of the blood, blood service personnel and others not under 
the direct supervision of the physician are not in a position to relieve 
the physician of the time and trouble associated with the use of 
conventional methods and apparatus for diluting packed red blood cells. 
Turning now to the use of whole blood as a substitute for diluting packed 
red blood cells, as previously discussed, it has long been recognized as 
wasteful and potentially dangerous in many, if not a majority of cases. 
For example, in Volume 212, No. 1 of the Journal of the American Medical 
Association, dated Apr. 6, 1970, in an article entitled "Whole Blood Use 
Called Wasteful," it is contended that "component transfusion therapy is 
better transfusion therapy," and, referring to a then new handbook, it is 
stated: "The use of whole blood is `shotgun` therapy, wasting valuable 
components and endangering the patient with the unnecessary burdens of 
volume, acidosis, electrolytes and antibodies." In the same article, a 
past president of the American Association of Blood Banks is reported as 
stating: "Acute blood loss resulting from surgery or trauma is about the 
only remaining case in which using whole blood remains preferable to 
components." 
In the same article it is stated: "Transfusion of red blood cells (also 
referred to as concentrated, packed, or enriched red blood cells) rather 
than whole blood, is generally the best and safest method of fulfilling a 
patient's need for increased oxygen-carrying capacity. Whether that need 
results from chronic anemia or acute blood loss, red blood cells, properly 
prepared, have the same shelf life as whole blood." 
In the article, some of the advantages of packed red blood cell 
transfusions pertinent to the present invention are listed: 
(1) The risk from metabolic by-products which accumulate in plasma during 
storage of whole blood (such as lactic acid, potassium, inorganic 
phosphate and ammonia) is reduced. 
(2) The risk of reactions to allergens and antibodies in plasma is reduced. 
(3) The risk of reactions to plasma protein antigens is reduced in 
multi-transfused recipients. 
In summary, the article concludes with the statement that, "it is likely 
that from 60% to 80% of blood transfusion needs can and should be met by 
use of red blood cells (rather than whole blood)." 
If packed red blood cells were used instead of whole blood, considerably 
less whole blood would be required to obtain the necessary component parts 
for specific applications. In spite of this fact, it is reported in the 
Lancet, Letters to the Editor, Feb. 15, 1969, at page 372, that "The high 
viscosity of packed red blood cells renders their clinical use very 
difficult." 
Even though the problems associated with the use of conventional methods 
and apparatus for diluting packed red blood cells was well recognized as 
far back as early 1969, both the problems and the absence of any adequate 
solution therefor has persisted until the present invention, as evidenced 
by a recent article in Transfusion. In an article entitled "Microaggregate 
Content and Flow Rates of Packed Red Blood Cells," Transfusion, 
September-October, 1977, pages 484-489, it is reported that: "It is 
frequently maintained that the flow rate of red blood cells is too slow to 
be useful during the brisk bleeding that may be encountered at 
operations." 
In addition to the foregoing considerations militating against the use of 
whole blood as a substitute for properly diluted packed red blood cells, 
there is the consideration of the amount of whole blood necessary to 
supply the present needs of both those using blood components and whole 
blood. 
The above quoted estimate of 60-80% of blood optimally being transfused as 
packed red blood cells is based on their limited use in surgery and trauma 
for the reasons discussed. If the dilution of packed red blood cells were 
made convenient and simple, it is likely that virtually all blood 
transfusions could be achieved using diluted packed red blood cells. This 
could result in an additional 1,000,000 liters of plasma from whole blood 
per year in this country, which would substantially reduce or eliminate 
the need for paid plasma donors. 
As the amount of blood and plasma obtained from commercial sources is 
reduced, the problems associated with hepatitis and other blood-related 
diseases are likely to also be reduced. Needless to say, the cost of 
collecting the blood will, of course, be reduced substantially. 
SUMMARY OF THE INVENTION 
In view of the foregoing, principal objects of the present invention are a 
method and apparatus for diluting packed red blood cells contained in a 
transfusion bag which are quick and easy to use, reliable and free of the 
potential hazards of bacterial contamination associated with prior known 
conventional methods and apparatus. 
In accordance with the above objects of the present invention, there is 
provided a flexible, squeezable diluent bag having a capacity of about 200 
cc. The capacity of the diluent bag corresponds to the volume of blood 
components removed from the whole blood in the first step of conventional 
blood processing. Extending from the bag is a hollow tubular assembly 
comprising a tubular member. Fitted to the free end of the tubular member 
is a conically-shaped male fitting. The male fitting is adapted to 
penetrate one of a plurality of ports in a conventional transfusion bag. 
Typically the port is elastic. As the fitting is fitted into the port, the 
port expands about the fitting and closes upon it as the head of the 
fitting passes through and into the transfusion bag. As the fitting passes 
into the transfusion bag, the port forms a fluid-tight seal therewith, 
preventing its non-destructive removal from the port. Alternatively, both 
ends of the tubular member may be fitted with such a fitting for insertion 
in both the transfusion and the diluent bags. 
Between the transfusion bag and the diluent bag, there is provided a 
uni-directional flow, fluid valve means. The fluid valve means allows 
fluid to flow from the diluent bag to the transfusion bag, but prevents 
fluid from flowing in the reverse direction from the transfusion bag to 
the diluent bag. 
In practice a physician ordering blood will receive one or more units of 
packed red blood cells in a transfusion bag having a plurality of 
inlet/outlet ports. When the packed red blood cells are received, the 
physician will ordinarily insert one end of an IV set in one of the 
inlet/outlet ports with the opposite end being provided with a needle or 
the like for inserting in a patient. Depending on the physician's needs, 
an equal number of bags of diluent may also be supplied with the 
transfusion bags. At the time of their delivery to the physician, the 
Blood Bank or other service may or may not have inserted the tubing from 
the diluent bags in one of the inlet/outlet ports of the transfusion bags. 
Whether this is done depends upon the physician's requirements and orders. 
In any event, if a diluent and a transfusion bag have been pre-coupled by 
the blood service, the diluent bag, being permanently and non-removably 
attached to the transfusion bag is readily available for inspection by the 
physician, who can determine by visual observation the nature and quantity 
of the diluent in the diluent bag. If the blood service diluted the packed 
red blood cells in the transfusion bag before delivery thereof to the 
physician, the inseparability of the diluent bag from the transfusion bag 
provides the physician with the information necessary to determine that a 
proper diluent in quantity and type was used. 
If the physician performs the diluting with the diluent bag pre-coupled to 
the transfusion bags, it is simply necessary for the physician to 
vigorously squeeze the diluent bag with one hand, causing all of the 
diluent to pass into the transfusion bag, with the one-way valve member 
preventing reverse fluid flow therefrom. The size and shape of the bag is 
chosen to insure single-handed operation. The turbulence generated by the 
vigorous squeezing of the diluent bag agitates the packed red blood cells, 
causing a rapid, homogeneous mixture of diluent and packed red blood 
cells. 
As can be seen from the above discussion, because of the controls 
exercisable in fabricating the diluent bags according to the present 
invention, the disadvantages of time-consuming and potentially incorrect 
diluting of packed red blood cells in a transfusion bag are avoided.

DETAILED DESCRIPTION 
Referring to FIG. 1, there is provided a conventional stanchion 1, 
comprising a pair of hooked members or hangers 2 and 3. Suspended from the 
hook 2 is a conventional transfusion bag 4. At the lower end of the 
transfusion bag 4 there is provided a pair of fitting receiving 
inlet/outlet ports 5 and 6. Extending from the inlet/outlet port 5 there 
is provided an IV set 7 fitted with a medication port 8a, a flow control 
valve member 8b and a needle 8c. The needle 8c is provided for insertion 
in a vein or the like of a patient. Suspended from the inlet/outlet port 6 
there is provided, according to the present invention, a diluent bag 9. 
Referring to the bag 9, the diluent bag 9 comprises a flexible, squeezable 
container having a volume of approximately 200 cc. Typically the bag 9 is 
made of plastic and has a size and shape such that all or most of the 
contents thereof can be expressed therefrom by a vigorous squeezing of one 
hand. 
Extending from one end of the bag 9 there is provided a tubular assembly 10 
comprising a hollow tubular member 10a. Fitted to one end of the tubular 
member 10a is a fitting 11. Fitted to the opposite end of the tubular 
member 10 there is provided a uni-directional flow fluid valve means 12. 
Coupling the valve means 12 to the diluent bag 9 is a tubular member 22. 
The opposite end of the member 22 is sealed to the bag 9 in a fluid-tight 
manner as by thermal bonding techniques. 
Referring to FIG. 2, the inlet/outlet port 6 of the transfusion bag 4 is 
provided with a cylindrical, relatively stiff inner tubular member 15. The 
tubular member 15 is provided for receiving a fitting and is integrally 
secured in the bag 4 as by a fluid-tight seal formed by thermal bonding as 
at 16. 
The fitting 11 attached to the end of the tubular member 10a is adapted for 
insertion in the member 15 of port 6 and has a conically-shaped head 
portion 17a, a cylindrical body portion 17b and a centrally located fluid 
passageway 18 extending therethrough. At the base of the conically-shaped 
head portion 17a, there is provided a radially outwardly extending annular 
shoulder 19. 
The tubular member 15 of the inlet/outlet port 6, though relatively stiff, 
is made of plastic or other flexible material, and is elastic so as to fit 
snugly around the cylindrical body 17b of the fitting 11 below the head 
portion 17a. 
In use, as the fitting 11 is forcibly pushed into the member 15 of the 
inlet/outlet port 6, the member 15 is caused to spread about the head 
portion 17a. As the shoulder portion 19 at the bottom of the head portion 
17a clears the interior end of the member 15, the fitting 11 is captured 
by the closing of the member 15 about the cylindrical body portion 17b. At 
this point it is no longer possible to withdraw the fitting 11 from the 
inlet/outlet port 6 nondestructively. Thus, in this manner there is 
provided a permanent fluid-tight connection between the diluent bag 9 and 
transfusion bag 4. 
Referring to FIGS. 3 and 4, the uni-directional flow fluid valve 12 is 
provided with a housing 20. Interior of the housing 20 there is a 
cylindrical tubular structure 21. Tubular structure 21 is coupled to the 
hollow tubing 22 connecting the input of the valve member 12 to the 
diluent bag 9. At its upper end, the tubular structure 21 is formed with a 
curved valve seat 23 for receiving a spherical valve member 24. The valve 
member 24 is resiliently held in closed relationship relative to the valve 
seat 23 by means of a flexible rod-like member 25 which extends from the 
interior wall portion of the housing 20. The tubular member 10a attached 
to the transfusion bag 4 is fitted to the output end of the 
uni-directional flow fluid valve means 12. 
The apparatus according to the present invention may be used in a number of 
ways. For example, a supply of diluent bags 9 may be kept in the operating 
room or other suitable location for use by a physician desiring to dilute 
packed red blood cells in a transfusion bag 4 which has been ordered from 
a blood service. Alternatively, an adequate supply of diluent bags 9 may 
be supplied with the transfusion bags 4, as ordered by a physician. In 
still another method, the diluent bag 9 may be pre-coupled to a 
transfusion bag 4 prior to its being delivered in response to an order 
from a physician. In any of the cases mentioned, when dilution of packed 
red blood cells is desired, a diluent bag 9, which is coupled to the 
transfusion bag 4 in the manner described above, is coupled so as to 
provide a permanent coupling between the diluent bag 9 and transfusion bag 
4. When required and, if not previously done, the physician may simply and 
with one hand grasp the diluent bag 9 and squeeze vigorously. As the 
physician squeezes the diluent bag 9, the pressure causes the spherical 
valve member 24 to press against the spring member 25 in the 
uni-directional flow valve means 12. As the spherical valve member 24 is 
moved from the valve seat 23, fluid from the diluent bag 9 flows through 
the valve means 12 and the tubular member 10 and into the transfusion bag 
4. Generally, the turbulence caused by the forced fluid flow into the 
transfusion bag 4 is sufficient to agitate the packed red blood cells to 
form a homogeneous mixture of diluent and red blood cells. The amount of 
diluent is premeasured and corresponds to the amount of plasma and other 
blood components removed from the red blood cells in the transfusion bag 
during the collection and processing of the blood. 
Typically, the diluting fluid in the diluent bag 9 is either isotonic or 
slightly hypotonic so as not to cause hemolysis. Also it would not 
normally contain any calcium which could neutralize the effect of the 
anti-coagulants and lead to clotting of the blood. 
Since packed red blood cells diluted with the apparatus of the present 
invention and in the manner described can be made to have a viscosity 
which should be acceptable for rapid transfusions, it may be possible by 
means of the present invention to reduce, if not eliminate entirely, 
dependence on all commercial sources of whole blood. This is because the 
components available from present levels of volunteer donors is sufficient 
so long as the requirements for low-viscosity whole blood can be supplied 
by properly diluted packed red blood cells as described herein. It is 
apparent, that if the dependence on commercial blood sources can be 
reduced or eliminated, many of the problems involving hepatitis and other 
blood disorders associated with blood obtained from such sources will be 
reduced and, hopefully, eliminated. While a preferred embodiment of the 
invention has been described, it is contemplated that those skilled in the 
art may make various changes and modifications to the embodiment described 
without departing from the spirit and scope of the present invention. For 
example, a fitting such as fitting 11, described above with respect to 
FIG. 2, may be used at the free end of the tubular member 22 for insertion 
in the diluent bag 9 in the same manner as that used for the bag 4. In any 
event, appropriate fluid-tight seals are provided for sealing the various 
bags during storage and shipment. Accordingly, it is intended that the 
invention be not limited to the embodiment disclosed but rather that its 
scope be determined by reference to the claims and their equivalents 
hereinafter provided.