Drainage and negative pressure
115 It was not disputed that the drainage of wound exudates was common in 1991. Two types of drainage are, however, relevant in this context, namely, passive drainage (where the fluid simply drains from the wound by the force of gravity) and active drainage, where the fluid is sucked out of the wound by negative pressure.
116 The parties disagreed on:
(a) whether, in 1991, active suction was only used for closed wounds, or whether it was also used for open wounds. KCI submitted that active suction by the use of negative pressure was confined to closed wounds, while S&N stated that it was also used for open wounds. KCI conceded that passive drainage of open wounds was common, but submitted that active suction was not applied to those open wounds; and
(b) whether the purpose of drainage in 1991 was only to remove fluid from the wounds, or whether it was also to assist in wound closure as effected by the V.A.C.® invention. KCI submitted that the purpose of drainage at that time was only to remove fluid, thereby allowing the wound to heal naturally, rather than maintaining negative pressure to accelerate wound closure. S&N did not dispute that the purpose of drainage was to remove fluid, but submitted that it was consistent with, and assisted, the ultimate purpose of promoting wound healing and the normal growth of granulation tissue. Thus, in S&N's submission, the distinction between the purposes of removal of fluid and wound healing was a false dichotomy.
117 Mr Ellis, Dr Williams, Dr Pohl, Professor Stacey, Professor Penington and Mr Osmond agreed that negative pressure (active suction) was used to drain exudates in the context of closed wounds (ie those that have been sutured).
118 Mr Ellis deposed that active suction was not used for open wounds in 1991, and that he had never seen suction applied to an open wound until he saw the V.A.C.® product. Similarly, Professor Marshall deposed that he was unaware of any medical application in 1991 of treating an open wound by sealing and suction. At trial, however, Professor Marshall conceded that he had used active suction on open wounds from time to time in order to avoid contamination of the skin.
119 Dr Williams deposed that active suction was regularly used for open wounds in 1991.
120 Dr Pohl deposed that he could not recall fistulae being drained by active suction in 1991, but nonetheless deposed that suction was maintained in "open drainage systems" as at 1991 for as long as required to remove effluent from the wound. He also deposed that "continuous suction" was sometimes used in open drainage systems, but not the regular "on/off cyclical application" of negative pressure claimed in the Patent. Accordingly, Dr Pohl appeared to acknowledge that active suction was used for open wounds at the relevant time.
121 Dr Williams deposed that, as at 1991, drainage promoted wound healing, including the growth of healthy granulation tissue, by removing harmful fluids which impeded the normal wound healing process. At trial, Dr Pohl agreed that fluids and exudates could impede the wound healing process.
122 In contrast, Mr Ellis deposed that the purpose of drainage was simply to remove fluid. At trial, he agreed that as at 1991, "the removal of exudate from wounds via drainage was certainly a common procedure… a common occurrence" but testified that the aim of removing fluid was to control the potential for infection and reduce the tension in the tissue. He rejected the proposition that reducing infection and tension were themselves directed at the overriding goal of promoting wound healing, but nonetheless accepted that drainage would achieve a "healing outcome" by reducing the chance of complications. He stated:
I would see it almost the other way around whereby the wound healing promotion is almost the secondary to the need for the removal of - so the drainage was more about, I guess, achieving a healing outcome by reducing the chance of complications.
123 Mr Ellis, in his affidavit, stated:
As at 1991… control of infection was another key aspect of wound treatment. For most wounds this meant keeping the wound clean, and clearing away debris and exudates… it was… commonly necessary to install an apparatus to drain infected or inflamed wounds of fluids and other exudates on an ongoing basis to facilitate healing.
124 While Mr Ellis acknowledged that drainage was used, he stated that:
[Up until 1990] [t]he vast majority of draining wounds I helped manage were "closed" wounds and therefore involved a "closed drainage system". In my experience, the vast majority of drainage systems used at the Royal Adelaide Hospital for closed wounds were passive systems whereby any fluid build-up was simply drained away by the force of gravity.
125 Mr Ellis stated that although he was also involved in, or knew of, a few instances of closed drainage systems which used active drainage, (in that a non-mechanical vacuum apparatus was involved to apply suction to the cavity to remove the fluid), he recalled that they were rare when compared to the number of closed abdominal wounds with passive drainage systems.
126 Mr Ellis was also aware that the Royal Adelaide Hospital used an "open" but passive (gravity) drainage system, commonly for treating fistulae, and never saw or heard of any sort of active suction being used to assist with that fluid drainage.
127 Mr Ellis deposed that:
As at November 1991 I had never heard of… negative pressure or suction being applied to a wound, other than in the specific context of fluid being drained from a cavity in a wound which had already been surgically closed.
128 Mr Ellis deposed that when he first saw the V.A.C.® product in 1996, he considered it was a revolutionary method of wound management, as he had never previously seen a device which created a negative pressure environment or applied suction pressure directly to the surface of an open wound or read of such a system or concept. Mr Ellis deposed that:
Certainly with my experience at the Royal Adelaide Hospital and subsequently, I had never seen suction applied to an open wound.
…
Throughout my time at the Royal Adelaide Hospital no suction drainage was used on fistulae or open wounds to my knowledge. In fact as at November 1991 I was not aware of suction drainage being used anywhere in relation to open wounds or fistulae.
129 While aware that Dr Williams asserted that open drainage suction systems were used for moderate to heavily draining wounds since the mid 1970s, Mr Ellis stated:
While that may be the case elsewhere (although I am not aware of it), it certainly was not the case at the Royal Adelaide Hospital during my tenure, and does not accord with my understanding of historical trends and approaches to wound treatment. Drainage of such wounds at that time was passive.
…
Throughout my time at the Royal Adelaide Hospital and throughout my subsequent career involved in teaching wound healing and treatment approaches, the use of drains was a well understood technique. Nonetheless it is clear that the purpose of the drains was to remove fluid. I certainly did not consider, and it was never suggested to me by any colleagues, surgeons, or any literature I read, that suction drains had or could be used as a method of treatment which would have a therapeutic effect above and beyond the straight forward removal of fluid.
130 Mr Ellis described the different types of drains with which he was familiar in 1991 as first, a passive closed drainage system (which was installed at the time of the operation and allowed for the drainage of wound fluids to the external environment); secondly, RediVacs or HaemoVacs, which were small suction-type devices; and thirdly, placement of bags over the top of the wound to collect the fluid. The first two types of drains were placed over the wound to allow the fluid from the fistula or the sinus or the open wound to drain directly into it. For very large wounds, Cryovac bags would be used with a border of hydrocolloid to collect fluid passively, occasionally using a tube connected to one end of the Cryovac bag, allowing the fluid to drain into an external collection device.
131 When asked about active suction methods, such as portable electric pumps or wall suction, Mr Ellis stated:
My experience did not include the use of those. I do not remember seeing them there. But I accept that… obviously that was going on somewhere because plenty of other people do remember seeing them. But in my experience, it was largely the passive drainage systems and the modified drainage systems that the stomal therapists put in place.
132 Mr Ellis acknowledged that in his experience, especially as at 1991, the treating surgeon typically ordered or instructed the use of a vacuum system, rather than the nursing staff deciding how to treat or manage wounds.
133 In contrast to Mr Ellis, Dr Williams, who worked at the same hospital for five or six years (albeit that they did not know one another), was aware of open drainage prior to 1991 of fistulae and moderately to heavily draining wounds. He also maintained that suction was not uncommonly used in closed drainage systems.
134 In his first affidavit, Dr Williams stated that in draining wounds that could be closed by primary intention:
I recall that from at least the 1970s up to November 1991, a suction drain would be placed in the cavity of the wound in circumstances where there was the potential for the build up of fluids. The suction drain was passed through the healthy skin adjacent to the wound and then laid along the base of the wound. The wound was then sutured shut and, in some cases, an adhesive seal or cover was applied over the wound. This was (and still is) known as a closed suction drainage system. The drains were generally used following hernia repairs, removal of pilonidal sinus disease, removal of a subcutaneous tumour or a cyst, many intra abdominal procedures and following a mastectomy. I personally saw and used these systems in the surgical wards in the Royal Adelaide Hospital during this period.
135 Dr Williams also recalled that from at least the 1970s up to November 1991, open drainage was used for fistulae with either a passive (gravity) drain or (especially for higher output fistulae) by the use of active (suction) drainage. Dr Williams maintained that since the mid 1970s the open drainage suction system was also used in other types of moderately to heavily draining wounds (such as a chronic abscess, chronic wound infection or a post-operative wound infection). Dr Williams stated that the open drainage system incorporated:
(a) a tube with an ending containing multiple perforations;
(b) a porous dressing, such as cotton gauze or 'combine' gauze, which is cotton wool between pieces of gauze or other porous fabric;
(c) a cover, such as a stoma bag or a long bag or a flexible plastic bag;
(d) an adhesive, such as Stomahesive, Stomahesive paste, which is like a glue, or Stomahesive tape, which is a 2mm thick material, which is adhesive on both sides so that it sticks to the skin surrounding the wound; and
(e) a source of suction (vacuum), such as wall suction, or one of the portable, electric suction units.
All of the items listed directly above were readily available for use in hospitals as at November 1991.
The system was applied to a heavily draining wound by packing the wound with the porous dressing. The perforated end of the tube was then laid across the wound bed, on top of the dressing. A portion of the skin surrounding the wound was covered with an adhesive, such as Stomahesive. The plastic cover was attached to the Stomahesive to form a sealed area around the wound. The tube came out through the plastic cover in such a way as to maintain the seal over the wound. The tube was then attached to a suction device and the fluid was sucked out of the wound into a canister.
136 Dr Williams further deposed:
The negative pressure wound dressings in common use today utilise the same principles and features as in the system I have described above. Over the course of the past decade or so, it has become generally accepted by clinicians involved in wound care that the negative pressure wound dressings in common use today improve the rate of healing in both wet and dry wounds.
137 In his second affidavit, Dr Williams disputed Mr Ellis' comment that active suction in closed drainage systems was rare. Dr Williams deposed:
Based on my experience and observations, I know there were more than a "few instances"… of the use of active suction prior to November 1991 in closed drainage systems. Active suction was used regularly in heavily draining wounds in this period. It was almost always used when the wound was producing a lot of fluid, as the use of gravity alone to drain the fluid was not efficient. The source of the suction would differ, depending on the nature of the wound and available resources, but included the RediVac or HaemoVac pumps, wall suction or the portable, electric suction pump units.
138 Dr Williams also disagreed with Mr Ellis' assertion that active suction was not used in the open drainage of fistulae or sinuses. Dr Williams deposed:
I recall that active suction was regularly used in open drainage systems for heavily draining wounds and fistulae… When a fistula or other type of wound was high output, active suction from either wall suction or from a portable electric suction pump was used as part of a sealed, open drainage system prior to November 1991.
139 Although Mr Ellis maintained that it was "startlingly new… that the negative pressure treatment was said to actually help accelerate the development of healthy granulation tissue in the wound" and he had "never seen a device which created a negative pressure environment or applied suction pressure directly to the surface of an open wound before I saw the VAC system", Dr Williams deposed that applying suction to an open wound was not new. He stated "as I have said, there were certain types of draining wounds and fistulae to which my colleagues and I applied scaled, open wound drainage systems with active suction before November 1991. In doing so we created a negative pressure environment under the seal and on the wound."
140 Dr Williams further deposed:
At or before November 1991 I knew, and I am aware from my discussions with surgical and nursing colleagues at the time that they also knew, that removing irritating or infected fluid from the wound promoted wound healing, and that the process of healing involved the growth of healthy granulation tissue. This is because the acidic or alkaline fluid in a wound can damage the wound and the skin surrounding the wound when they come into contact. If you can remove the unhelpful fluid then normal wound healing processes can commence and granulation tissue can begin to grow in the wound within two to four days.
…
KCI claims the KCI VAC accelerates healing by promoting granulation tissue growth. It is said by KCI in its promotional material that this is one of the main functions of the KCI VAC. The purpose of the sealed, open wound drainage systems I have described was to remove harmful fluids from the wound and the skin surrounding the wound, so that those fluids did not impede or prevent the normal wound healing processes, which of course includes the growth of granulation tissue and the contraction of the wound. Ultimately I do not consider the differences between the two systems in terms of their effect on wound healing to be significant.
…
Mr Ellis says… that as at November 1991 he was not aware of suction drainage being used anywhere in relation to open wounds. As I have said this was not my experience. Nor does it appear to be the experience of Mr Pohl… whom I understand to be recollecting the use of sealed, open wound drainage systems [in] his affidavit.
141 In cross-examination, Dr Williams agreed that the purpose of, and the effect of, a closed drainage system in a sutured wound is to clean the fluid out of the wound so that the wound can heal spontaneously or naturally. He stated that the object in managing the effluent from the fistulae to which an open drainage system was applied was to remove it to avoid damage to the surrounding skin and tissue, and to minimise the need for wound dressing changes.
142 Dr Williams explained that in passive drainage a stoma bag or the like would be put over the wound, and the fluid from the fistula would be allowed to drain into the plastic bag which would be emptied periodically. If, however, active drainage were used, tubing would be placed into the bag and sealed around the outlet of the bag and connected to some form of suction, which would remove fluid continuously into a container. That technique was to drain the effluent away until such time as the clinician formed the view that the harmful fluid had reduced to a level where it could be contained with a dressing, after which the natural wound healing process could commence.
143 Dr Williams testified that in such cases granulation tissue might commence to form, even before two days. He also agreed that ordinarily, if the undesirable fluid were removed, normal wound healing processes could commence and granulation tissue would begin to grow within about two to four days. Fluid would suppress normal wound healing, which relied on the formation of granulation tissue. The latter might nevertheless form even whilst drainage is in process, if the wound was otherwise clean, but not at a normal rate.
144 Dr Williams said that the purpose of the active drainage system was to clean the wound of harmful fluids so they did not impede the normal wound healing process, with the added benefit of minimising the number of frequently painful dressing changes. The active drainage system both promoted healing and facilitated closure.
145 Dr Pohl, in his affidavit, agreed that "[i]n 1991, it was common practice to insert drains under closed wounds following surgery".
146 He deposed that:
In my time working in the [Colon and Rectum Unit at Sydney Hospital], and in the subsequent period prior to 1991, it was my experience that fistulae were drained passively and I do not recall fistulae being drained by active suction.
…
As at 1991, it was my experience that the porous dressings, such as gauze, that were used with open drainage systems were used to absorb fluid from a wound and debride dead material, not to prevent hypergranulation.
…
It was my experience using open drainage systems as of 1991 that suction was only maintained for as long as it was required to remove effluent from the wound.
…
It was my experience as of 1991 that continuous suction was sometimes used in open drainage systems, not the uniform ratios or regular on/off cyclical application of negative pressure claimed in the Patent.
…
It was my experience as at 1991 that drains as depicted [by Figure MCS-B of the Stacey affidavit] were often used under sutured wounds that were closed by primary intention. However, I do not recall continuous active suction attached to wall suction being used with this or any other type of closed wound.
147 At trial, Dr Pohl agreed that in addition to infection, fluids or exudates could impede the wound healing process.
148 Professor Marshall, in his first affidavit, deposed that he was:
aware in 1991 that various suction devices had been used in surgery (including plastic surgery) for a long time, at least from the late 1950s - early 1960s to prevent the accumulation of fluids or exudate. A suction device was usually inserted into a cavity within the body. The suction technique consisted of inserting one end of a drain tube into the cavity space, and the other side of the tube would then be connected to a suction bottle that applied continuous suction… The Patent teaches that an open wound may be treated by sealing it and applying suction to it. As at 1991 I was not aware of a medical application of suction in this way.
149 At trial, Professor Marshall agreed that it would have been reasonable, in 1991, to use suction to remove excess fluids and that there were methods of doing it without closing the wound. He stated:
[W]e would use what was called a sump drain… which was to put a tube within the wound to the bottom of the wound with holes in it to act like the sump of a motor car, so any fluid collecting would be in the bottom of it, and then put a tube down the middle of that sump drain connected to suction but without sealing it. Just, as I say, as open suction.
150 Professor Marshall stated:
[B]ecause I was so steeped in the notion that I could use suction within a closed surgical wound and that an open wound was a different thing that could drain on its own, I have to confess to you, I did not [think to put a seal over the top of an active suction system].
151 When asked whether he used active suction on open wounds from time to time, he responded "[y]es, in the system that you were describing to avoid the contamination of the skin."
152 Professor Stacey, in his first affidavit, deposed that as at the late 1980s:
[D]rainage bottles with vacuum were used to remove fluid from cavity wounds which were closed surgically in order to remove excess blood or tissue fluid and to maintain appropriate moist wound environments. I used wall suction to create the negative pressure in the drainage bottle, or pre-vacuumed bottle. Once I had done this, I closed the valve on the tubing attached to the bottle, connected this tubing to a drainage tube that I had inserted into the patient, opened the valve on the bottle, and relied on the suction to extract the fluid from the cavity.
…
It was well known in Australia even before the 1980s that it was important to drain fluid out of a cavity wound, otherwise that fluid collects in the wound and prevents the apposition of the wound edges, thereby delaying the healing process and possibly acting as a site for infection. The removal of the excess fluid reduces the dead space and thus the size of the wound cavity, which means the wound can heal more quickly, quite simply because there is a smaller cavity to fill… The removal of excess fluid also assisted in maintaining an optimum moist wound environment that is conducive to healing. The mechanism for removing fluid… meant less dressing changes were required.
153 Professor Penington, in his first affidavit, deposed that during the period from 1987 to November 1991, he used "vacuum drains to drain fluid (wound exudate) from closed surgical wounds".
154 Mr Osmond, in his first affidavit, deposed that he developed "a device in the mid-1980s that was directed to draining wounds which had been closed by suturing… Ultimately, however, I abandoned the commercialisation of my device, primarily through lack of funds."
155 In his second affidavit, Mr Osmond deposed that:
In use for wound drainage, the Clements regulator I sold in the 1980s was connected to the wall suction and then connected, via a tube, to a collection bottle. The collection bottle was then connected to a second bottle via another tube. The second bottle was then connected to the patient via another tube… It was part of my role with Clements to visit hospitals in Australia and observe systems in use, and I saw wall suction being used in this way for drainage of closed wounds many times.
…
I recall that during the 1980s I did see wall suction being used, with low suction regulators, to actively drain closed sutured wounds many times.
…
While I agree [with Mr Ellis] that it is likely that the "majority" of closed wounds were drained at that time at Royal Adelaide by passive (gravity) drainage, I am aware that the hospital also used non-mechanical active suction, such as RediVac systems, as well as mechanical active suction, that is, electric pumps, for closed wound drainage in this period.
…
During my time selling pumps for Clements, as I have stated above and in my First Affidavit, I visited hospitals regularly to observe procedures and demonstrate products. I recall observing active suction, using electric pumps or wall suction, being used to drain both cutaneous and sub-cutaneous wounds. I do not recall at which hospitals I saw this being done, but saw it being done a number of times. The systems I observed for cutaneous wounds included a drain tube, connected at one end to the suction source, laid across the wound, gauze covering the tube and then a plastic adhesive film or adhesive dressing covering the tube and gauze in order to seal the wound. If the wound was sub-cutaneous, the drain tube was laid beneath the skin.