Court of Appeal Judgment in KCI Licensing Inc & Others v Smith & Nephew plc & Others: contributory infringement through supply of negative pressure wound therapy device

31 January 2011

Gerry Kamstra

KCI sued Smith & Nephew (S&N) under two patents, EP (UK) patents Nos. 0 777 504 ('504) and 0 853 950 ('950), relating to negative pressure wound therapy ("NPWT") devices. NPWT involves treating large open wounds by the use of a screen over the wound, covering this with a larger material such as a flexible polymer sheet so as to provide a seal and applying a vacuum - the vacuum increases the blood flow which speeds up healing. The main idea of the ‘504 patent is to use a disposable canister and tubing to collect exudate from the wound so as to prevent any contamination of the pump generating the vacuum.  And that of the ‘950 patent (a divisional of the ‘504 patent) is to have a disposable canister with an outlet tube (to the suction pump) with a bacterial filter and an inlet tube (from the wound pad) with a quick disconnect coupling and a clamp. At first instance Mr Justice Arnold held that S&N’s “GO” and “EZ” pumps and canisters infringed both patents. On appeal S&N conceded that the EZ pump and canister infringed, so the Court of Appeal (Longmore and Jacob LJJ and Kitchin J) was concerned solely with the appeal and cross-appeal on the judge’s infringement findings in relation to the GO device and his findings on validity of the ‘504 and ‘950 patents.

In relation to infringement of the ‘504 patent, it had been conceded that claim 1 was invalid whereas claim 5 had been held by the judge to be independently valid and infringed.  This part of the appeal turned upon construction of two of the elements required by claim 5, namely elements [8] and [10] (from claim 1) out of the following: [1] a therapeutic apparatus for stimulating healing of a wound in mammals which comprises [2] a porous pad which is permeable to fluids for introduction into the wound [3] a dressing for covering the wound and providing an air-tight seal therearound [4] a drainage tube connecting the pad to a suction pump contained in a housing so that negative pressure can be applied to the wound, to draw fluids therefrom [5] said tube being connected to the pump via a disposable canister for collecting fluids sucked from the wound [6] said canister having an inlet connected to the drainage tube and a suction port connected to the pump [7] said suction port incorporating a filter to prevent passage of liquid therethrough [8] and said canister and said housing having a guide for aligning the container in a recess in the housing such that the suction port is connected to the pump [9] a latch for engaging with and releasably holding the canister in the recess and [10] means for detecting when the canister is substantially filled with liquid and generating a signal which causes the pump to be deactivated [11] wherein said pad is a polymer foam having interconnecting cells and [12] wherein the foam is a reticulated foam having at least 90% of interconnecting cells.  The judge had held that the requirement of "deactivation" in element [10] was satisfied if the pump ceased to pump fluid for whatever reason, and in so doing he differed from the parallel judgment of the Landgericht in Mannheim (Case No. 7 O 114/9). S&N contended that this was wrong and that if the GO pump stops pumping fluid into the canister for the simple reason that the canister is full, that is not "deactivation" as called for by the claim. The Court of Appeal agreed, as the GO pump does not have any “means” for “detecting” and “generating” which causes “deactivation” (even though there is “deactivation”).  As regards element [8], the Court of Appeal pointed out that it requires a "recess in the housing" and that the "container" be aligned "in" that recess. This language simply did not extend to the GO container, which is fitted over the housing.

In relation to infringement of the ‘950 patent, again KCI conceded that claim 1 was invalid - instead KCI relied on contributory infringement (under section 60(2) Patents Act 1977) of claims 7 and 8. The elements of claim 1 are: [1] A disposable canister for use in wound dressing treatment apparatus comprising a wound dressing pad and a suction pump for applying negative pressure to the wound dressing pad [2] said canister comprising a moulded plastics container having an inlet connected to a flexible inlet tube and an outlet for connection to the suction pump [3] said outlet incorporating a bacterial filter and said inlet tube having a quick disconnect coupling device for connection to a flexible drainage tube leading to the wound dressing pad [4] and said inlet tube including clamp means for preventing escape of liquid from the container. Claim 7 requires in addition that [the canister] includes a gel-forming substance which is capable of immobilising drainage fluids within the canister; and claim 8 requires a canister as claimed in any of the preceding claims in combination with a wound dressing pack, the wound dressing pack comprising a reticulated open-celled foam pad having at least 90% of interconnecting cells and being connected to a drainage tube terminating in a quick disconnect coupling device adapted to couple with [a] coupling device attached to the inlet tube which is attached to the inlet of the canister, said drainage tube including clamp means to prevent the drainage tube leaking liquid when the coupling devices are disconnected.  It was common ground that the GO canister as sold by S&N does not include a clamp means on the inlet tube as required by integer [4] of claim 1 and of course claims 7 and 8, so KCI alleged indirect infringement under s.60(2).  The judge held that "In the light of [this] evidence I find that it is probable that from time to time some medical personnel using the GO system have clamped the end of the inlet tube when changing the canister. Moreover, I consider that it would have been obvious to a reasonable person supplying GO canisters that this would be likely to occur"; but then found that S&N had not infringed because “the effect of the evidence is that, when medical personnel did this, they will have done it on their own initiative when faced with the need to change a filled canister without risking the escape of fluids. There is no evidence that GO canisters have been purchased by medical institutions with the intention that the canisters should be used in conjunction with a clamp on the inlet tube”.

As events turned out, after the judge so concluded the Court of Appeal gave judgment in Grimme v Scott [2010] EWCA Civ 1110 where it clarified the scope and proper interpretation of s.60(2), including the requirement of knowledge. It held:

i) The question is what the supplier knows or ought to know about the intention of the person who is in a position to put the invention into effect – the person at the end of the supply chain.

ii) It is enough if the supplier knows (or it is obvious to a reasonable person in the circumstances) that some ultimate users will intend to use or adapt the "means" so as to infringe.

iii) There is no requirement that the intention of the individual ultimate user must be known to the defendant at the moment of the alleged infringement.

iv) Whilst it is the intention of the ultimate user which matters, a future intention of a future ultimate user is enough if that is what one would expect in all the circumstances.

v) The knowledge and intention requirements are satisfied if, at the time of supply or offer to supply, the supplier knows, or it obvious to a reasonable person in the circumstances, that ultimate users will intend to put the invention into effect. This has to be proved on the usual standard of the balance of probabilities. It is not enough merely that the means are suitable for putting the invention into effect (for that is a separate requirement), but it is likely to be the case where the supplier proposes or recommends or even indicates the possibility of such use in his promotional material. 

Applying these principles the Court of Appeal concluded that S&N had infringed because it was probable that from time to time some medical personnel using the GO system would have clamped the end of the inlet tube when changing the canister. Further, it would have been obvious to a reasonable person supplying GO canisters that that this would be likely to occur.

On the issue of validity, S&N raised two questions: first, whether it was obvious in 1994 to use reticulated foam as the dressing for NPWT - the alleged invention of claim 5 of the '504 patent and claim 8 of the '950 patent; second, whether it was obvious in 1994 to put a gelling agent in the canister to prevent spillage of liquid – the alleged invention of claim 7 of the '950 patent.  In spite of the Biogen principle (an appellate court should be very cautious in differing from the judge's evaluation where the application of a legal standard such as negligence or obviousness involves no question of principle but is simply a matter of degree) the Court of Appeal allowed these questions to be raised and allowed the appeal from the finding of validity of claim 7 of the ‘950 patent; but rejected the appeal in relation to the claim 5 of the ‘504 patent (which was not infringed) and claim 8 of the ‘950 patent.  This left S&N with a finding of contributory infringement of claim 8 of the ‘950 patent.