WO2005123001A1

WO2005123001A1 - A medical fluid bag arrangement and a method of providing, arranging and treating medical fluids

Info

Publication number: WO2005123001A1
Application number: PCT/SE2005/000776
Authority: WO
Inventors: Ola Carlsson; Massimo Bormetti
Original assignee: Gambro Lundia AB
Current assignee: Gambro Lundia AB
Priority date: 2004-06-18
Filing date: 2005-05-24
Publication date: 2005-12-29
Anticipated expiration: 2006-12-18
Also published as: EP1755521B1; EP1755521A1

Abstract

The invention concerns a medical fluid bag arrangement comprising a fluid bag. The fluid bag has at least a first (11) and a second (12) compartment. The first compartment (11) contains a first fluid and the second compartment (12) contains a different second fluid. At least the second fluid has such a composition that it runs the risk of being degraded if the second fluid receives too much energy during sterilisation. The fluid bag arrangement comprises a special cover (31, 37) which is arranged over at least one side of the second compartment (12), but which is not arranged around the whole fluid bag. The special cover (31, 37) is positioned such that the risk that the second compartment (12) receives too much energy during sterilisation is reduced. The invention also concerns a method of providing, arranging and treating medical fluids.

Description

A medical fluid bag arrangement and a method of providing, arranging and treating medical fluids

BACKGROUND OF THE INVENTION

The present invention concerns a medical fluid bag arrangement which comprises a fluid bag with at least a first and a second compartment, which are separated from each other such that different fluids can be arranged in said compartments. The first compartment contains a first fluid and the second compartment contains a second fluid, which is different from the first fluid. At least the second fluid has such a composition that it runs the risk of being degraded during the sterilisation of the fluid bag.

The invention also concerns a method of providing, arranging and treating medical fluids.

EP 0 596 497 B1 describes a bag for containing at least two separate substances which are to be mixed with each other. The bag comprises two chambers: a larger chamber and a smaller chamber. The chambers are separated from each other by a separating section. This separating section can be opened in order to mix the two substances. The smaller chamber is positioned over the larger chamber with the separating section between the chambers. The reason for this arrangement is to prevent that the two substances are accidentally mixed with each other. The document also mentions that sterilisation of the bag can be performed before or after the bag is folded.

EP 0 972 506 A2 describes a flexible bag for containing at least two separate substances to be mixed for medical use. For this purpose, the bag has two chambers. The bag is fitted with an outer covering.

The covering can either be applied to the bag when the bag is fully extended or it can be applied to the bag when the bag has been folded. The document also describes that the bag is sterilised in an autoclave.

A large number of further medical fluid bags are known. Fig. 1 schematically shows an example of a fluid bag that is used for peritoneal dialysis. This schematic illustration is similar to the fluid bag Gambrosol™ Trio sold by Gambro AB, Sweden. The fluid bag comprises three different compartments: 11 , 12, 13. Inlet ports 111 , 112, 113 are provided for allowing the compartments 11 , 12, 13 to be filled with fluids. An exit port 23 is also provided. The dialysis fluid can exit through this port 23 in order to be delivered to a patient. Before the bag is used for peritoneal dialysis, the contents of the compartments 11 , 12, 13 can be mixed with each other. For this purpose the bag includes frangible pins 15, 17 which enable a user to open a passage between the compartments 12 and 13 and the compartment 11. Instead of frangible pins 15, 17, other kinds of means for providing a passage between the compartments can be used. Such means can for example be provided in the form of so- called peel seals. The reason for providing the fluid bag with different compartments is that different fluids cannot be stored for a long time in a mixed state.

Fluids for peritoneal dialysis are known to a person skilled in the art and will therefore not be described in detail here. However, normally such a dialysis fluid is an aqueous solution that comprises an osmotic agent such as a carbohydrate, for example glucose, glucose polymers or the like, electrolytes, for example sodium, potassium, calcium, magnesium, and a buffer source in the form of or- ganic acid salts such as sodium lactate, sodium bicarbonate or sodium pyruvate. The osmotic agent may for example be included in the compartment 12 or in both the compartments 12 and 13. It is for example possible to include osmotic agents of different concentrations and/or of different kinds, in the compartments 12 and 13. It is also possible that the compartments 12 and 13 contain different volumes of the same osmotic agent. This makes it possible to choose the concentration of the osmotic agent in the final dialysis solution by mixing the contents of one or both of the compartments 12 and 13 with the content of the compartment 11. Electrolytes may also be included in the compartments 12 and 13.

Fig. 2 shows a schematic view in the direction ll-ll indicated in Fig. 1. Fig. 2 also schematically illustrates a protective coating 19. The fluid bag is also often delivered together with a drain bag 21 , which can be provided inside the protective coating 19. The drain bag 21 is used to collect used dialysis fluid from a patient. Inside the pro- tective coating 19 normally also tubing 20 (only indicated in Fig. 2) is provided. The tubing 20 includes a tube connected to an exit port 23 (see Fig. 1 ) and a tube connected to the drain bag 21. These tubes often merge together to a common tube to be connected to the patient.

Another example of a fluid bag for peritoneal dialysis fluid is described in the document WO 99/27885 A1.

When a medical fluid is exposed to heat during sterilisation, the fluid may, depending on which fluid it is, be degraded. This degradation may be different for different fluids. For example, the chemical composition of the medical fluid may be influenced such that the fluid does not work as well as intended for its medical purpose. The degradation may also result in the formation of toxic products in the fluid.

It is, for example, known that such degradation can occur in fluids for peritoneal dialysis (PD). A PD fluid usually includes an osmotic agent. This osmotic agent may for example be glucose. There is a risk for the glucose to be degraded during the sterilisation process. On one hand, the sterilisation has to be performed such that the patient, who is to receive the fluid, does not run the risk of being infected and, on the other hand, care has to be taken not to sterilise the fluid in such a way that the composition of the fluid changes by e.g. degradation. For the purpose of not giving rise to infection, the sterilisation has to be performed such that official requirements are fulfilled. The sterilisation dose has to be sufficiently high such that the fluids in all compartments are sterilised to the required degree. When for example sterilising a fluid bag of the kind which is shown in Fig. 1 , it is thus necessary to apply a sufficiently high sterilisation dose such that the fluid in the compartment 11 is sterilised to a re- quired degree. The smaller compartments 12, 13 thereby risk being exposed to an unnecessary high sterilisation dose, i.e. too much energy is transferred to the fluids in the smaller compartments during sterilisation. If for example one or both of the smaller compartments 12, 13 include glucose, a degradation of the substance in these compartments 12, 13 may occur. For example, toxic glucose degradation products such as 3-deoxyglucosone, acetaldehyde, formaldehyde, 3,4-dideoxyglucosone-3-ene and methylglyoxal can be formed. Such degradation products are cytotoxic and are able to promote the formation of advanced glycation end products known to accelerate arteriosclerosis. It is thus very important to make sure that as little degradation products as possible are formed during the sterilisation.

One solution to this problem is disclosed in the documents WO 97/05852 A1 and WO 93/09820 A1. According to these documents, it is important to make sure that the glucose compound is kept at a high concentration and optionally at a low pH during sterilisation.

SUMMARY OF THE INVENTION

An object of the present invention is to further reduce the risk for the formation of degradation products when sterilising medical fluid bags of the kind described in the first paragraph above. An object is thereby to provide a medical fluid bag arrangement which is such that the formation of degradation products during sterilisation is eliminated or reduced. A further object is to provide such a fluid bag arrangement which is easy and inexpensive to produce.

In this document primarily a peritoneal dialysis (PD) fluid will be discussed as an example of a medical composition. However, the invention is also applicable to other medical fluids which risk being degraded during sterilisation when being sterilised for medical use. Such fluids may for example be parenteral nutrition solutions or other sterile solutions for intravenous use, which comprise carbohydrates, proteins or peptides.

The objects of the invention are achieved by a fluid bag arrangement of the kind described in the first paragraph above and which is characterised in that the fluid bag arrangement comprises a special cover which is arranged over at least one side of the second com- partment, but which is not arranged around the whole fluid bag, wherein said special cover is positioned such that the risk that too much energy is transferred to the second compartment during sterilisation is reduced, while permitting that the fluids in the different compartments are sterilised to a sufficient degree.

By providing such a special cover and by positioning this cover in a suitable manner, it is achieved that the whole fluid bag is sterilised to a sufficient degree at the same time as it is avoided that the mentioned second compartment receives an unnecessary high ster- ilisation dose. The formation of unwanted degradation products can therefore be avoided to a large extent.

Preferably, the whole medical fluid bag arrangment, including the special cover, is of such a form that it is suitable to be delivered to a hospital or to a patient without removing any part of the medical fluid bag arrangement. The whole medical fluid bag arrangement can thus go through the whole sterilisation process without removing any party of the medical fluid bag arrangment. Thereafter, the whole medical fluid bag arrangment (possibly after have been put in a cardboard box or other suitable external package) is ready to be delivered to a hospital or directly to a patient's home.

It may be noted that the present invention can also be combined with the teachings of the above mentioned documents WO 97/05852 A1 and WO 93/09820 A1. The present invention does however not necessarily have to be combined with the teaching of these documents. According to an embodiment of the invention, the fluid bag is arranged folded such that the second compartment is folded back such that it lays over at least part of said first compartment. By folding the fluid bag in this manner, the risk that the second compartment receives a too high sterilisation dose is further reduced. By the combination of such a folded fluid bag and the above described special cover, it has been found that an excellent sterilisation can be performed of the fluid bag arrangement while avoiding formation of unwanted degradation products.

Please note than when in this document it is said that something is arranged "over" the fluid bag or "over" some part or portion thereof or is said to be folded "over" something, this of course also means that if the whole arrangement is turned around, the thing that is said to be "over" will instead be "under". The claimed subject matter thus covers both these possibilities even if only the word "over" or the like is used.

According to a further embodiment, the special cover is arranged at least over the folded second compartment. The special cover can be arranged only over the folded second compartment. However, it is also possible that the special cover is arranged over both the second compartment and the first compartment and also over pos- sible further compartments that are included in the fluid bag.

According to an alternative embodiment, the fluid bag is arranged non-folded such that the second compartment is positioned beside the first compartment and wherein the special cover is positioned such that the second compartment completely or to a large extent is insulated by the special cover but such that the first compartment is not insulated at all by the special cover or is insulated to a substantially lesser degree than the second compartment. The special cover can be arranged on one or on both sides of the second com- partment. The special cover can for example be arranged to extend around (be wrapped around) the second compartment. By in this manner providing the second compartment with a sufficient special cover, it can be avoided that the second compartment receives a too high sterilisation dose even if the fluid bag is not folded as according to the preferred embodiment.

Preferably, the volume of the first fluid in said first compartment is a least two times the volume of the second fluid in said second compartment. The volume of the first fluid may also be essentially larger than this, for example at least 5 times or at least 10 times or at least 15 times the volume of the second fluid in the second com- partment. In particular, if the volume of the first fluid is essentially larger than the volume of the second fluid there is a high risk that the second fluid receives an unnecessary high sterilisation dose. However, this can be avoided with the present invention even if the volume of the first fluid is much larger than the volume of the sec- ond fluid.

The fluid bag can comprise a third compartment which contains a third fluid which is different from at least said first fluid. The third fluid may of course also be different from the second fluid. Of course, also the third compartment may suitably be folded together with the second compartment over the first compartment. Furthermore, the special cover may according to a preferred embodiment be positioned both over the folded second compartment and over the folded third compartment. Thereby, also the risk for degradation of the third fluid can be reduced.

According to an embodiment, the fluid bag is arranged with means which enables a user to open a passage in said fluid bag between at least said first and second compartments, such that in said fluid bag, the second fluid can be mixed with at least said first fluid. Such means can for example constitute frangible pins or peel seals as described above.

According to an embodiment, the content of the fluid bag is such that the fluid bag contains a dialysis fluid for use in a process of hemodialysis, hemodiafiltration, hemofiltration or peritoneal dialysis, and/or a replacement fluid, suitable to be delivered to a patient in order to replace the ultrafiltrate that is withdrawn from a patient in a process of hemodialysis, hemofiltration, hemodiafiltration or peritoneal dialysis, or that the content of the fluid bag is such that the fluid bag contains a concentrate for such a dialysis or replacement fluid. Preferably, the fluid bag contains a dialysis fluid for peritoneal dialysis or a concentrate for such a dialysis fluid for peritoneal dialysis. The invention is particularly useful in connection with such fluids, but, as mentioned above, the fluid bag may also comprise other sterile medical fluids.

According to an embodiment, said special cover comprises a drain bag that is to be used for receiving a fluid drained off from a patient in a process of peritoneal dialysis. Such a drain bag is often used in connection with continuous ambulatory peritoneal dialysis (CAPD). It has therefore been found to be particularly advantageous and practical if the drain bag is used as the special cover.

The fluid bag arrangement can also comprise tubing connected to said drain bag and to said fluid bag. In order to avoid contamination when the fluid bag and the drain bag are used, it is advantageous to provide these bags with the necessary tubing before the bags are delivered to the user.

Preferably, the fluid bag arrangement also comprises a protective coating which surrounds the whole fluid bag. By providing such a protective coating, it is ensured that the fluid bag, and possible drain bag and tubing, are prevented from being contaminated. Furthermore, with such a protective coating it is possible to ensure that the fluid bag is maintained folded and that the special cover is maintained in the intended position.

According to one embodiment, said special cover comprises a first portion of said protective coating that is thicker than the remaining portion of the protective coating or that is made of a material with a lower heat conductivity than the remaining portion of the protective coating. According to this embodiment, the special cover thus constitutes a portion of the protective coating. It may therefore not be necessary to have another separate special cover, in addition to the protective coating, in this case.

The protective coating can comprise a first sheet and a second sheet which have been bonded to each other to form said protective coating, wherein one of said first and second sheets constitutes said first portion. If the protective coating comprises two sheets, one sheet can thus be made of a thicker material, or of a material with a lower heat conductivity, in order to fulfil the function of the special cover.

If the special cover comprises a drain bag or another separate special cover, said protective coating preferably surrounds both the whole fluid bag and the whole drain bag or said another separate special cover. As mentioned above, the protective coating thereby ensures that the drain bag or another separate special cover is maintained in position. Furthermore, in case the fluid bag is folded, it can be ensured that the fluid bag is not accidentally unfolded. Furthermore, the protective coating protects the fluid bag and the drain bag or other separate special cover from being contaminated.

The object of the invention is also achieved by a method of providing, arranging and treating medical fluids comprising the following steps: providing a medical fluid bag comprising at least a first and a second compartment, which are separated from each other such that different fluids can be arranged in said compartments, providing a first fluid in said first compartment and a second fluid in said second compartment, wherein the second fluid is differ- ent from the first fluid and wherein at least the second fluid has such a composition that it risks being degraded if the second fluid receives too much energy during sterilisation of the fluid bag, arranging a special cover over at least one side of the second compartment, but not around the whole fluid bag, wherein said spe- cial cover is positioned such that the risk that too much energy is transferred to the second compartment during sterilisation is reduced, arranging the so obtained fluid bag arrangement in a sterilising chamber, and performing a sterilisation such that the fluids in the different compartments are sterilised to a sufficient degree.

With this method, advantages corresponding to those described above in connection with the fluid bag arrangement are achieved.

Preferably, the method is performed such that the special cover re- mains in the position defined above during the whole sterilisation process, i.e. during the whole sterilisation time necessary to sterilise the whole medical fluid bag to a sufficient degree. In other words: the special cover is not removed during the sterilisation process. Furthermore, preferably, the special cover is such that it is suited to remain in the position that it has during the sterilisation process also after the sterilisation process has been completed. Preferably, the special cover is such that it is suited to remain in the position that it has during the sterilisation process all the time until the sterilised medical fluid bag has been delivered to a hospital or to a patient.

Further advantageous features concerning different manners of carrying out the method according to the invention are clear from the dependent claims. Also these features bring about advantages cor- responding to those described above in connection with the embodiments of the fluid bag arrangement.

In particular, it is preferred that said special cover is positioned and said fluid bag, if folded, is folded such that the fluids in the different compartments during the sterilisation step are sterilised to a sufficient degree while preventing that the fluid in some compartment receives too much energy during the sterilisation, such that by said method unnecessary degradation of the fluids in the fluid bag during the sterilisation is prevented. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 schematically shows a view of a fluid bag according to the prior art.

Fig. 2 schematically shows the fluid bag of Fig. 1 in the direction ll-ll together with a drain bag and a protective coating.

Fig. 3 schematically shows a view similar to that of Fig. 1 of another embodiment of a fluid bag.

Fig. 4,5,6,7 and 8 show very schematically views from the side, similar to that of Fig. 2, of different embodiments of a medical fluid bag arrangement according to the invention.

Fig. 9 schematically shows a medical fluid bag arrangement according to the invention positioned in a sterilisation chamber.

Fig. 10 shows a flow chart exemplifying a method according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

As already explained above, Fig. 1 schematically shows a fluid bag according to the prior art and Fig. 2 shows a fluid bag arrangement according to the prior art. Embodiments of a medical fluid bag arrangement according to the invention will now be described primarily with reference to Fig. 4, 5, 6, 7 and 8. The arrangement according to the invention includes a fluid bag. This fluid bag can be of a known kind, for example of the kind described in connection with Fig. 1. The fluid bag is preferably formed by a flexible plastic material such as PVC or another plastic material, or by a combination of different plastic materials. Fig. 3 illustrates another example of a fluid bag that can be used in the arrangement according to the invention. The fluid bag according to Fig. 3 is similar to the fluid bag of Fig. 1. However, the fluid bag according to Fig. 3 differs from the fluid bag of Fig. 1 in that the first compartment 11 does not extend between the second compartment 12 and the third compartment 13. Instead, an inlet port 1 11 is in this case arranged in the lower part of the fluid bag as indicated in the figure. The fluid bag of Fig. 3 also differs from the fluid bag of Fig. 1 in that no frangible pins 15 and 17 are used. Instead, the fluid bag according to Fig. 3 includes peel seals 25, 27 which can be opened such that the content of one or both of the compartments 12 and 13 can be mixed with the content of the compartment 11. The fluid bag is preferably formed by a flexible plastic material or by a combina- tion of different plastic materials, for example including polypropene and polyamides.

A fluid bag that forms part of the arrangement according to the invention may of course be designed in different manners than what is shown in Fig. 1 and Fig. 3. However, the fluid bag that forms part of the arrangement according to the invention always includes at least two compartments 11 , 12. The present invention can be applied to different medical fields where a fluid bag has a compartment that includes a fluid that runs the risk of being degraded dur- ing the sterilisation process. As mentioned above, according to an example of the application of the invention, the fluid bag includes a dialysis fluid for peritoneal dialysis (PD). Such a fluid bag may for example have three compartments 11 , 12, 13 as illustrated in Fig. 1 and 3. The first compartment 11 is often much larger than the sec- ond compartment 12 and the third compartment 13. For example, the first compartment 11 may include 1960 ml of fluid, the second compartment 12 may include 62 ml of fluid and the third compartment may include 103 ml of fluid. The first compartment 11 can include the necessary buffer and electrolyte solution, while the sec- ond compartment 12 and the third compartment 13 may include a glucose solution. The fluids in the second compartment 12 and the third compartment 13 can be the same. This makes it possible for a user to choose a certain glucose concentration in the dialysis fluid by mixing the content of the second compartment 12 or of the third compartment 13 or of both the compartments 12 and 13 with the content of the first compartment 11.

The fluid bag has to be sterilised to a sufficient degree in order to prevent that the patient who receives the fluids is infected and in order to fulfil official requirements. The sterilisation may for example be performed in an autoclave chamber by saturated steam un- der pressure. The sterilisation conditions, for example temperature and time, have to be selected such that a sufficient sterilisation is obtained. These conditions have to be chosen such that in particular the content of the largest compartment 11 is sufficiently sterilised. As explained above, this means that the smaller second and third compartments 12, 13 may be exposed to an unnecessary high sterilisation dose. The fluids in the smaller compartments may thus be heated too quickly and/or maintained at an elevated temperature for an unnecessary long time. In other words: too much energy is transferred to the fluids in the smaller compartments during the sterilisation. This may lead to the formation of unwanted or even toxic degradation products in these smaller compartments 12, 13.

Fig. 4 illustrates schematically a first embodiment of a fluid bag arrangement according to the invention. This arrangement includes a fluid bag, for example of the kind described above. The fluid bag is folded such that the second compartment 12 is folded back such that it lays over at least part of the first compartment 11. The bag can for example be folded along the hatched line 29 shown in Fig. 3. This means that both the second compartment 12 and the third compartment 13 will be folded such that they lay over the first compartment 11. If the fluid bag is provided with frangible pins, like in Fig. 1 , it may be advantageous to fold the fluid bag somewhat lower as seen in Fig. 1 , i. e. below the frangible pins 15, 17. A special cover 31 is arranged at least over one side of the second fluid compartment 12 (and in this case also over the third fluid compartment 13). The special cover 31 is however not arranged around the whole fluid bag. The special cover 31 may constitute a drain bag. However, it is also possible that the special cover 31 is a separate cover that is used only for the purpose of reducing the sterilisation dose which the smaller compartments 12, 13 receive. In any case, the special cover 31 is arranged such that the second compartment 12 (and according to this embodiment also the third compartment 13) does not receive too much energy during sterilisation, while permitting that the fluids in the different compartments, i. e. in particular in the compartment 11 , are sterilised to a sufficient degree. Fig. 4 illustrates that the special cover 31 is arranged substantially only above the second 12 and third 13 compartments. The special cover 31 can for example be a folded drain bag.

The embodiment of Fig. 5 shows that the special cover 31 , for ex- ample in the form of a drain bag, is arranged to extend both over the smaller compartments 12, 13 and over the larger compartment 11.

The embodiment of Fig. 6 shows that the special cover 31 is ar- ranged both over and below the folded smaller compartments 12 and 13. The special cover 31 may in this case for example be a folded drain bag.

Preferably, the special cover 31 is formed of a material that will not adhere to the fluid bag during sterilisation. This means that if the fluid bag is made of PVC, the special cover 31 is preferably not made of PVC. Alternatively, it is possible to arrange a layer (not shown) between the special cover 31 and the fluid bag in order to prevent that the special cover 31 adheres to the fluid bag during sterilisation. The fluid bag arrangement may also include a separate sheet 33 (see Fig. 4, 5 and 7) which is arranged between the folded portion of the bag and the compartment 11 in order to prevent that the folded portion will be caused to adhere to the compartment 1 1 during sterilisation. According to one embodiment, such a separate sheet 33 can also be made to provide an insulating effect, for example by being sufficiently thick. Depending on how the heating of the fluid bag is effected when the fluid bag is sterilised, it may be advantageous if the separate sheet 33 provides such an insulating effect. If for example the sterilisation is performed such that the heating is effected from below the fluid bag, it can (if the fluid bag is positioned as shown in Fig 4,5 and 7) be advantageous if the sepa- rate sheet 33 has such insulating properties.

The fluid bag arrangement according to the invention also preferably includes a protective coating 35 which surrounds the whole fluid bag. Such a protective coating is well known to a person skilled in the art. The protective coating 35 is preferably made of a material that will not adhere to the parts arranged inside the protective coating 35 during sterilisation.

Fig. 7 shows an embodiment of the arrangement according to the invention that includes a particular kind of protective coating 35. The protective coating 35 here consists of an upper sheet 37 and a lower sheet 39 that are bonded together in order to provide a sealed protective coating 35 surrounding the whole fluid bag. This is known in this technical field. However, what is particular to the protective coating 35 according to Fig. 7 is that the upper sheet 37 is made of a special material that is different from the material of the lower sheet 39. For example, the upper sheet 37 can be formed of a thicker material or may be made of a material with a lower heat conductivity. This can for example be achieved if the upper sheet 37 includes more layers than the lower sheet 39. The upper sheet 37 therefore, according to this embodiment, constitutes the special cover 31 that fulfils the function of reducing the risk for the formation of unwanted degradation products in the smaller compartments 12 and 13 of the fluid bag. It should be noted that it is of course also possible that an additional special cover 31 , for example in the form of a drain bag, is arranged inside the protective coating 35 also in the embodiment according to Fig. 7.

Fig. 8 schematically shows an alternative embodiment of a fluid bag arrangement according to the invention. According to this embodiment, the fluid bag is not folded. Instead, the special cover 31 is arranged to surround the smaller compartments 12, 13 but the larger compartment 11. The special cover 31 is thus positioned such that the second 12 and third 13 compartments completely or to a large extent are insulated by the special cover 31 but such that the first compartment 11 is not insulated at all by the special cover 31 (or, alternatively, is insulated to a substantially lesser degree than the smaller compartments 12,13). If this special cover 31 is designed to have sufficient insulating properties, it is possible to achieve the object of the invention without folding the bag. Also according to this embodiment, the special cover 31 may constitute a drain bag.

Although not shown in the figures 4 to 8, the medical fluid bag arrangement may also comprise suitable tubing 20 attached to the fluid bag and to a possible drain bag that forms part of the ar- rangement.

Fig. 9 schematically shows a sterilisation chamber 41. This sterilisation chamber 41 may constitute an autoclave. Since such an equipment is known to a person skilled in the art, it will not be dis- closed in detail here. The chamber 41 has a support surface 45 for the fluid bag arrangement that is to be sterilised. The chamber 41 can be filled with saturated steam under pressure. When a fluid bag arrangement according to the invention is sterilised in such a chamber 41 , it is prevented that the mentioned smaller compart- ments 12, 13 are exposed to an unnecessary high sterilisation dose. Therefore, the occurrence of unwanted degradation products in the fluid bag is reduced.

Fig. 10 shows a schematic flow chart of one manner of carrying out a method according to the invention.

A medical fluid bag comprising at least two compartments 11 , 12 is provided. Fluids are provided in these compartments 11 , 12. The fluid bag may of course comprise more than two compartments and different medical fluids can be arranged in the different compartments. For example, the fluid bag can include fluids in the different compartments that are to be mixed with each other in order to form a PD fluid.

In next step, the fluid bag is folded, for example as described above. A special cover 31 is then arranged over at least the folded fluid bag compartment 12. The special cover 31 may constitute a drain bag that is to be used for receiving a fluid drained off from a patient in a process of peritoneal dialysis. The special cover 31 may be arranged in different manners as described above. A protective coating 35 is provided such that this protective coating surrounds the fluid bag and the special cover 31. The fluid bag arrangement obtained in this manner is positioned in a sterilising chamber 41. Sterilisation is then performed such that the fluids in the different compartments 11 , 12, 13 are sterilised to a sufficient degree while preventing that the fluid in some compartment 12, 13 receives too much energy during the sterilisation. Thereby unnecessary degradation of the fluids in the fluid bag is prevented.

Laboratory experiments have been performed in order to investigate the properties of the present invention. In these experiments a fluid bag similar to the one illustrated in Fig. 1 has been used. The different compartments 11 , 12, 13 were filled with fluids as described above in order for the bag to contain a PD fluid. The fluid bag was sterilised in an autoclave. In a first case, the fluid bag was sterilised in a non-folded state with a drain bag positioned on top of the fluid bag (substantially as illustrated in Fig. 2). In a second case, the fluid bag was folded (similar to what is illustrated in for example Fig. 4) but without positioning any drain bag or other special cover on top of the fluid bag. In a third case, the fluid bag was folded in the same manner as in case two, but also provided with a drain bag on top of the fluid bag (similar to what is shown on Fig. 5).

After the sterilisation had been performed, the concentration of the following three degradation products in the smaller compartments 12, 13 was measured: 3-DG (3-deoxyglucosone), 5-HMF (5- hydroxymethylfurfural) and 3,4-DGE (3,4-dideoxyglucosone-3-ene). Furthermore, the F₀-value was measured in the smaller compart- ments 12, 13 and in the larger compartment 1 1. It can be noted that the Fo-value is a measure of the sterilisation dose. This concept is known to a person skilled in the art. The concept is explained in the literature, see for example the European Pharmacopoeia-1997, p. 288. The result of the tests is shown in the table below. It should be noted that the concentrations and the F₀-values were substantially the same in the two smaller compartments 12, 13. Therefore, only one value is shown for the smaller compartments 12, 13.

It can be seen in the table that the concentration of degradation products is substantially reduced in the third case (i. e. a folded bag with a drain bag on top). It can also be seen that in the first two cases, the F₀-value for the smaller compartments 12, 13 is essentially higher than for the larger compartment 11. This means that if the larger compartment 1 1 is to receive a sufficiently high sterilisation dose, the smaller compartments 12, 13 will receive an unnecessary high sterilisation dose. However, in the third case, the Fo- value for the smaller compartments 12, 13 is in fact a little lower than the F₀-value for the larger compartment 11. This means that the sterilisation conditions in this case can be chosen such that the smaller compartments 12, 13 will be sterilised to a sufficient degree. At the same time also the larger compartment 11 will be sterilised to a sufficient degree. An unnecessary high sterilisation dose in the smaller compartments 12, 13 is therefore avoided.

With the present invention it can thus be ensured that a sufficient sterilisation of a medical fluid bag arrangement is achieved at the same time that the formation of unwanted degradation products is reduced.

The invention is not limited to the described embodiments but may be varied and modified within the scope of the following claims.

Claims

1. A medical fluid bag arrangement comprising a fluid bag with at least a first (11 ) and a second (12) compartment, which are separated from each other such that different fluids can be arranged in said compartments (11 , 12), wherein the first compartment (11 ) contains a first fluid and the second compartment (12) contains a second fluid, which is different from the first fluid, wherein at least the second fluid has such a composition that it runs the risk of being degraded if the second fluid receives too much energy during sterilisation of the fluid bag, characterised in that the fluid bag arrangement comprises a special cover (31 , 37) which is arranged over at least one side of the second compartment, but which is not arranged around the whole fluid bag, wherein said special cover (31 , 37) is positioned such that the risk that too much energy is transferred to the second compartment (12) during sterilisation is reduced, while permitting that the fluids in the different compartments (11 , 12) are sterilised to a sufficient degree.

2. A medical fluid bag arrangement according to claim 1 , wherein the fluid bag is arranged folded such that the second compartment (12) is folded back such that it lays over at least part of said first compartment (11 ).

3. A medical fluid bag arrangement according to claim 2, wherein the special cover (31 , 37) is arranged at least over the folded second compartment (12).

4. A medical fluid bag arrangement according to claim 1 , wherein the fluid bag is arranged non-folded such that the second compartment (12) is positioned beside the first compartment (11 ) and wherein the special cover (31 ) is positioned such that the second compartment (12) completely or to a large extent is insulated by the special cover (31 ) but such that the first compartment (1 1 ) is not insulated at all by the special cover (31 ) or is insulated to a substantially lesser degree than the second compartment (12).

5. A medical fluid bag arrangement according to any of the preceding claims, wherein the volume of the first fluid in said first compartment (11 ) is a least two times the volume of the second fluid in said second compartment (12).

6. A medical fluid bag arrangement according to any of the preceding claims, wherein the fluid bag comprises a third compartment (13) which contains a third fluid which is different from at least said first fluid.

7. A medical fluid bag arrangement according to any of the preceding claims, wherein the fluid bag is arranged with means (15, 17, 25, 27) which enables a user to open a passage in said fluid bag between at least said first (11 ) and second (12) compartments, such that in said fluid bag, the second fluid can be mixed with at least said first fluid.

8. A medical fluid bag arrangement according to any of the pre- ceding claims, wherein the content of the fluid bag is such that the fluid bag contains a dialysis fluid for use in a process of hemodialy- sis, hemodiafiltration, hemofiltration or peritoneal dialysis, and/or a replacement fluid, suitable to be delivered to a patient in order to replace the ultrafiltrate that is withdrawn from a patient in a process of hemodialysis, hemofiltration, hemodiafiltration or peritoneal dialysis, or that the content of the fluid bag is such that the fluid bag contains a concentrate for such a dialysis or replacement fluid.

9. A medical fluid bag arrangement according to claim 8, wherein the fluid bag contains a dialysis fluid for peritoneal dialysis or a concentrate for such a dialysis fluid for peritoneal dialysis.

10. A medical fluid bag arrangement according to claim 9, wherein said special cover (31 ) comprises a drain bag that is to be used for receiving a fluid drained off from a patient in a process of peritoneal dialysis.

11. A medical fluid bag arrangement according to claim 10, wherein the arrangement comprises tubing (20) connected to said drain bag (31 ) and to said fluid bag.

12. A medical fluid bag arrangement according to any of the preceding claims, comprising a protective coating (35) which surrounds the whole fluid bag.

13. A medical fluid bag arrangement according to claim 12, wherein said special cover (37) comprises a first portion (37) of said protective coating (35) that is thicker than the remaining portion (39) of the protective coating (35) or that is made of a material with a lower heat conductivity than the remaining portion (39) of the protective coating (35).

14. A medical fluid bag arrangement according to claim 13, wherein said protective coating (35) comprises a first sheet (37) and a second sheet (39) which have been bonded to each other to form said protective coating (35), wherein one of said first (37) and second (39) sheets constitutes said first portion.

15. A medical fluid bag arrangement according to any of the claims 12-14, wherein said special cover (31 ) comprises a drain bag or another separate special cover and wherein said protective coating (35) surrounds both the whole fluid bag and the whole drain bag (31 ) or said another separate special cover.

16. A method of providing, arranging and treating medical fluids comprising the following steps: providing a medical fluid bag comprising at least a first (11 ) and a second (12) compartment, which are separated from each other such that different fluids can be arranged in said compartments (11 , 12), providing a first fluid in said first compartment (11 ) and a sec- ond fluid in said second compartment (12), wherein the second fluid is different from the first fluid and wherein at least the second fluid has such a composition that it risks being degraded if the second fluid receives too much energy during sterilisation of the fluid bag, arranging a special cover (31 , 37) over at least one side of the second compartment (12), but not around the whole fluid bag, wherein said special cover (31 , 37) is positioned such that the risk that too much energy is transferred to the second compartment (12) during sterilisation is reduced, arranging the so obtained fluid bag arrangement in a sterilising chamber (41 ), and performing a sterilisation such that the fluids in the different compartments (11 , 12) are sterilised to a sufficient degree.

17. A method according to claim 16, comprising the following step before the sterilisation is carried out: folding the fluid bag such that the second compartment (12) is folded back such that it lays over at least part of said first compartment (1 1 ).

18. A method according to claim 17, comprising the following step before the sterilisation is carried out: arranging the special cover (31 , 37) at least over the folded second compartment (12).

19. A method according to claim 16, comprising the following steps before the sterilisation is carried out: arranging the fluid bag non-folded such that the second compartment (12) is positioned be- side the first compartment (11 ) and arranging the special cover (31 ) such that the second compartment (12) completely or to a large extent is insulated by the special cover (31 ) but such that the first compartment (11 ) is not insulated at all by the special cover (31 ) or is insulated to a substantially lesser degree than the second com- partment (12).

20. A method according to any of the claims 16-19, comprising the following steps before the sterilisation is carried out: designing the fluid bag and arranging said first and second fluids such that the volume of the first fluid in said first compartment (11 ) is a least two times the volume of the second fluid in said second compartment (12).

21. A method according to any of the claims 16-20, comprising the following steps before the sterilisation is carried out: providing said fluid bag in a design such that it also comprises a third com- partment (13) and arranging a third fluid, which is different from at least said first fluid, in said third compartment (13).

22. A method according to any of the claims 16-21 , comprising the following step before the sterilisation is carried out: providing the fluid bag with means (15, 17, 25, 27) which enables a user to open a passage in said fluid bag between at least said first (11 ) and second (12) compartments, such that in said fluid bag, the second fluid can be mixed with at least said first fluid, when the fluid bag is to be used after having gone through the sterilisation.

23. A method according to any of the claims 16-22, comprising the following step before the sterilisation is carried out: selecting the fluids in said fluid bag such that the content of the fluid bag is such that the fluid bag contains a dialysis fluid for use in a process of hemodialysis, hemodiafiltration, hemofiltration or peritoneal dialysis, and/or a replacement fluid, suitable to be delivered to a patient in order to replace the ultrafiltrate that is withdrawn from a patient in a process of hemodialysis, hemofiltration, hemodiafiltration or peritoneal dialysis, or such that the content of the fluid bag is such that the fluid bag contains a concentrate for such a dialysis or replacement fluid.

24. A method according to claim 23, comprising the following step before the sterilisation is carried out: selecting the fluids in said fluid bag such that the fluid bag contains a dialysis fluid for peritoneal dialysis or a concentrate for such a dialysis fluid for peritoneal dialysis.

25. A method according to claim 24, wherein said special cover (31 ) comprises a drain bag that is to be used for receiving a fluid drained off from a patient in a process of peritoneal dialysis.

26. A method according to claim 25, comprising the following steps before the sterilisation is carried out: providing a tubing (20) and connecting the tubing (20) to said drain bag (31 ) and to said fluid bag.

27. A method according to any of the claims 16-26, comprising the following step before the sterilisation is carried out: providing a protective coating (35) which surrounds the whole fluid bag.

28. A method according to claim 27, wherein said protective coating (35) is selected such that said special cover (37) comprises a first portion (37) of said protective coating (35) that is thicker than the remaining portion (39) of the protective coating (35) or that is made of a material with a lower heat conductivity than the remain- ing portion (39) of the protective coating (35).

29. A method according to claim 28, wherein said protective coating (35) comprises a first sheet (37) and a second sheet (39) which are bonded to each other to form said protective coating (35), wherein one of said first (37) and second (39) sheets constitutes said first portion.

30. A method according to any of the claims 27-29, wherein said special cover (31 ) is selected to comprise a drain bag or another separate special cover and wherein said protective coating (35) is arranged to surround both the whole fluid bag and the whole drain bag (31 ) or said another separate special cover.

31. A method according to any of the claims 16-30, wherein said special cover (31 , 37) is positioned and said fluid bag, if folded, is folded such that the fluids in the different compartments (11 , 12, 13) during the sterilisation step are sterilised to a sufficient degree while preventing that the fluid in some compartment receives too much energy during the sterilisation, such that by said method un- necessary degradation of the fluids in the fluid bag during the sterilisation is prevented.