T 0404/16 21-07-2020

1. The invention

The invention relates to a hemofiltration system, in particular for performing a Continuous Renal-Replacement Therapy (CRRT), indicated for critically ill patients (paragraphs [0003] to [0011] of the patent).

CRRT is a kind of slow and continuous dialysis therapy, which is better tolerated than the traditional dialysis as it does not involve sudden changes in the blood which may cause cardiovascular instability. Continuous Veno-Venous Hemofiltration (CVVH), Continuous Arterio-Venous Hemofiltration (CAVH), Continuous Veno-Arterial Hemofiltration (CVAH), Continuous-VenoVenous-Hemo-DiaFiltration (CVVHD or CVVHDF) and Continuous-Arterio-VenousHemo-DiaFiltration (CAVHD or CAVHDF), mentioned in paragraphs [0003] and [0004] of the patent are all special kinds of CRRT.

A system according to claim 1 is schematically depicted in Figures 3 and 4 reproduced below.

FORMULA/TABLE/GRAPHIC

FORMULA/TABLE/GRAPHIC

The hemofiltration system comprises an access line (1) for carrying blood from the patient to a blood filter (60), a return line (2) for carrying blood from the blood filter (60) back to the patient, a first pump (14) for pumping blood through the access line, a second pump (24) for introducing an anticoagulant solution into the blood traveling through the access line, a third pump (23) for introducing substitution fluid into the blood, a fourth pump (16) for introducing a calcium and magnesium solution into the blood, a fifth pump (50) for introducing substitution fluid into the blood travelling through the return line, and a processing unit for controlling the flow rates of the first to fourth pumps. When one pump halts for any reason, the other pumps also stop pumping, wherein the stops of the blood pump and the anticoagulant pump are delayed after the other pumps have stopped.

According to the patent (paragraph [0054]) this is done to fill the return line with blood containing anticoagulant, to avoid the risk of clotting inside this line when the blood is not circulating.

2. Main request - sufficiency of disclosure

2.1 The appellant argued that the feature of claim 6 "wherein the processing unit (72) computes the amount of substitution fluid introduced in the blood from the weight measured by the scale" was not sufficiently disclosed, in essence because it would be impossible to compute the amount of the fluid already introduced in the blood. However, what the processing unit has to compute according to the claim is not the substitution fluid already introduced, but the fluid to be introduced. As indicated by the Board in the communication of 17 March 2020, this is clearly derivable from the subsequent passage of the claim "wherein the processing unit (72) controls the flow rate of the third pump (23) and the fourth pump (16) to introduce the computed amount of substitution fluid to the blood" (emphasis added). How this is done is clearly disclosed in paragraphs [0046], [0056] and [0057] of the patent.

2.2 As regards the feature of claim 6 according to which the processing unit controls the third pump and the fourth pump to introduce the computed amount of substitution fluid into the blood, the Board notes that the fifth pump - and not the fourth pump - is defined as a further pump for pumping substitution fluid in the preceding claims. However, this may result, at most, in a clarity problem which was already present in the claims as granted. The Board has no power to examine such a potential lack of clarity in opposition appeal proceedings (G 3/14, Order). How the processing unit controls the flow rates of the third, fourth and fifth pump is explained in detail in paragraphs [0056] and [0057] of the patent.

2.3 In conclusion, the subject-matter of claim 6 is sufficiently disclosed. Hence, the ground for opposition under Article 100(b) EPC does not prejudice the maintenance of the patent on the basis of the claims found allowable by the Opposition Division.

3. Added subject-matter

3.1 The appellant argued that the feature of claim 1 "wherein the fourth pump (16) is coupled to the return line (2) and the third pump (23) is coupled to the access line (1)", which was derived from claim 4 as originally filed, added subject-matter because claim 4 additionally defined that the third pump was coupled to the access line between the first pump and the filter.

However, as correctly noted by the Opposition Division in the impugned decision (point 3 of the "grounds for the decision"), according to page 22, lines 13 to 15, of the application as filed "in one embodiment, the pre-dilution line 31 is connected to the access line l pre-blood pump 14". It means that, according to this passage, the third pump can be coupled to the access line in any position, either before or after the blood pump.

3.2 The appellant's argument that the passage on page 22, lines 13 to 15, did not concern a system additionally comprising a fifth pump is not accepted. First, the passage belongs to the detailed descriptions of Figures 3 and 4, which include a fifth pump, and mentions the reference signs appearing in those figures. Moreover, the presence of a fifth pump for introducing substitution fluid in the return line as stipulated by the claim is obviously in no technical relationship with the exact position of the third pump in the access line.

3.3 In conclusion, the subject-matter of claim 1 does not extend beyond the content of the application as filed. It follows that the ground for opposition under Article 100(c) EPC does not prejudice the maintenance of the patent on the basis of the claims found allowable by the Opposition Division.

4. Clarity

The appellant argued that the feature of claim 1 "when one pump halts for any reason, the other pumps also stop pumping, wherein the stops of blood pump (14) and anticoagulant pump (24) are delayed after the other pumps have stopped" was unclear. The person skilled in the art was left in doubt whether the term "of the other pumps" referred to all the other pumps mentioned in the claim or to all the other pumps of any hemofiltration system falling within the scope of the claim.

The Board notes that the patent as a whole teaches that the claimed stopping of the pumps is intended to handle a situation of malfunction of the hemofiltration system, by stopping the treatment. The term "of the other pumps" can therefore only refer to all the pumps of a hemofiltration system falling within the scope of the claim, except the pump which has already stopped, irrespective of whether all these pumps have explicitly been mentioned in the claim. This makes technical sense, since letting one pump run when the blood pump has already stopped may dangerously change the composition of the blood present in the system. Hence, in a situation of malfunction, all the pumps of the hemofiltration system have to stop. This construction of the claim is consistent with the description, paragraph [0054], which specifically concerns the feature objected to, explains that in such a system the infusion of all fluids are regulated and controlled together and goes on to explain that "when one pump halts for any reason, the stops of blood pump 14 and anticoagulant pump 24 are preferably delayed by, for example, about 10 seconds after the other pumps have already stopped".

It follows that claim 1 meets the requirements of clarity (Article 84 EPC).

5. Inventive step

5.1 The appellant argued against inventive step of the subject-matter of claim 1, starting from D1 or D2.

5.1.1 D1 concerns a system that can be employed for performing hemofiltration in the context of CRRT (page 8, lines 16 to 30). Such a system is schematically depicted in Figure 3 reproduced below.

FORMULA/TABLE/GRAPHIC

D1 discloses an access line (102) with a blood pump (112), an anticoagulant pump (120), a blood filter (140), a return line (104), a pump (32) suitable for introducing a calcium solution into the blood, a substitution pump (114a) for introducing substitution fluid from a supply of substitution fluid into the blood traveling through the access line, and a substitution pump (114b) for introducing substitution fluid from a supply of substitution fluid into the blood traveling through the return line (page 14, line 22 to page 15, line 11). These elements are controlled by a processing unit (70, Figure 2).

5.1.2 D2 concerns a system that can be employed for performing hemofiltration in intensive therapy (paragraphs [0002] and [0010]). Such a system is schematically depicted in Figure 1 reproduced below.

FORMULA/TABLE/GRAPHIC

D2 discloses an access line (3a) with a blood pump (21), an anticoagulant syringe (35) for introducing an anticoagulant into the blood, a blood filter (2), a return line (3b), a pump (9) suitable for introducing a calcium solution into the blood (paragraphs [0149] to [0151]), a pump (19) for introducing substitution fluid from a supply of substitution fluid into the blood traveling through the access line (paragraphs [0046] and [0047]) and a further pump (13) for introducing substitution fluid from a supply of substitution fluid into the blood traveling through the return line (paragraph [0075]). These elements are controlled by a processing unit (40, paragraph [0105]).

5.1.3 Neither D1 nor D2 disclose that when one pump halts for any reason, the other pumps also stop pumping, wherein the stops of blood pump and anticoagulant pump are delayed after the other pumps have stopped.

This feature is a functional feature, which prescribes what the claimed system must be capable of doing under a certain condition of use. Hence, it has a limiting effect on the scope of the claim.

As the respondent submitted, the patent (paragraph [0054]) explains that this distinguishing feature allows to fill the return line with blood containing anticoagulant, to avoid the risk of clotting inside this line when the blood is not circulating.

This solves the objective technical problem of increasing the safety of a patient under treatment, in case the treatment is continued after the stop of all pumps, for instance in case of a malfunction.

5.1.4 Although D1 discloses that the blood pump and the anticoagulant pump should be regulated together, as noted by the appellant, this concerns a condition of normal use, not the situation wherein the pumps stop as in case of a malfunction. Consequently D1 does not address the objective technical problem mentioned above.

5.1.5 The appellant also pointed to D3 to D7. Although these documents may teach the administration of a solution containing calcium and magnesium and its effects in connection with blood treatment systems employing citrate as an anticoagulant, as argued by the appellant, they do not do it in relation to the objective technical problem. Moreover, the claimed solution to that problem is not taught by these documents, since none of them discloses said distinguishing features.

The appellant's reference to the common general knowledge is of little relevance, since no proof was provided that the distinguishing feature had commonly been implemented for the solution of the objective technical problem.

5.1.6 The appellant also referred to D8. This document was filed with the statement of grounds of appeal and is directed against the subject-matter of an independent claim which was present in requests only filed by the proprietor one month before the oral proceedings before the Opposition Division (auxiliary requests 4 and 5 at that time). Those requests were not allowed by the Opposition Division, which allowed a further request comprising that claim as the only independent claim during the oral proceedings. Under these circumstances the Board made use of its discretion under Article 12(4) RPBA 2007 and admitted D8 into the proceedings.

D8 concerns a system for CRRT, in particular hemofiltration, comprising, inter alia, a blood pump and an anticoagulant pump (page 9). On page 29, referred to by the appellant, it is explained that pressing a button "Behandlung Start/Stop" activates a function of the system in which a pre-dilution pump, a post-dilution pump and a filtrate pump are stopped while the blood pump continues working. On page 30, also referred to by the appellant, it is disclosed that a syringe containing an anticoagulant can be replaced activating a further function of the system. This implies an interruption of the administration of the anticoagulant. However, there is no disclosure in D8 that these functions are in any relation to each other. In particular, there is no disclosure in D8 that the anticoagulant delivery can only be interrupted by activating the function of the syringe replacement. Moreover, there is no disclosure either that when the function "Behandlung Start/Stop" is activated, the anticoagulant syringe continues delivering anticoagulant. The appellant's argument that it would be implicit or obvious for the person skilled in the art to continue the delivery of anticoagulant is not convincing. Since the blood pump continues running when the function "Behandlung Start/Stop" is activated, the delivery of anticoagulant is of no technical importance. Hence, D8 does not disclose the distinguishing feature of claim 1. It does not address the objective technical problem either.

5.1.7 It follows that starting from D1 or D2, in combination with each other, the common general knowledge, D3, D4, D5, D6, D7 and/or D8 the person skilled in the art would not arrive at the subject-matter of claim 1 in an obvious way.

5.2 The appellant also argued starting from D3, D7 or D8. However, as explained, these documents do not disclose the distinguishing feature identified above. That feature is not disclosed in relation to the objective technical problem by any of the cited prior art, either. Hence, the person skilled in the art would not arrive at the subject-matter of claim 1 in an obvious way starting from any of these documents.

5.3 In conclusion, the subject-matter of claim 1 - and a fortiori of dependent claims 2 to 7 - of the request found allowable by the Opposition Division involves an inventive step (Article 56 EPC).