Vittorio Cherchi – a surgeon at the Azienda Sanitaria Universitaria Friuli Centrale – together with Umberto Baccarani and Andrea Risaliti, has patented the ‘Easy removal surgical T-drain‘: a variant of the Kehr tube used in liver transplants and liver and biliary surgery.
As reported by the Ministry of Health and the CNT – Centro Nazionale Trapianti (National Transplant Centre) in the preliminary report – published in January 2023 – “Donazione e trapianti 2022 di organi, tessuti e cellule staminali emopoietiche“ (“Donation and Transplantation 2022 of Organs, Tissues and Haematopoietic Stem Cells“), Italy shows a significant increase in transplants and donations.
Already in 2021, there is an upward trend, which shows that the pre-Covid balance of the national transplant system has been restored and even exceeded.
In 2022, there were 2,038 kidney transplants, 1,474 liver transplants, 254 heart transplants, 138 lung transplants and 38 pancreas transplants, with a total of 1,830 donors.
The increase in numbers is a positive sign for the Sistema Sanitario Nazionale italiano (Italian National Health Service). It demonstrates not only the efficiency of hospital centres and staff, but also the great work of public research. More and more researchers are developing projects that aim to innovate in the biomedical sector and have an (immediate) impact on society and the health of all citizens.
These technologies also include variations on instruments or devices from national medicine. One example is the ‘Easy removal surgical T-drain‘: a project designed and developed by Vittorio Cherchi, Umberto Baccarani and Andrea Risaliti for the Università di Udine and the Azienda Sanitaria Universitaria Friuli Centrale.
The facilitated drainage device is a structural modification of the Kehr tube: a traditional surgical tool that has made medical history in liver transplantation and liver and biliary surgery.
‘Easy removal surgical T-drain’ is the most viewed technology of the month for May 2023 on the Knowledge Share platform. We delved into the project with Vittorio Cherchi, who left the project and started to share his views and ideas for comparison.
The Kehr tube project: from idea to market potential. How it works and how it improves the ‘status quo’ of currently used technologies.
The Kehr tube is a device used in biliary, resective and liver transplant surgery. Its function is to drain the bile produced by the liver out of the body. It is a highly specialised area of medicine. The fact that ‘Easy removal surgical T-drain‘ has been displayed so many times on the KS platform (around 320 in May 2023) is significant and certainly gives me great pleasure.
It is a small T-shaped latex tube invented by the German surgeon Hans Kehr, consisting of a body of variable length and a shorter horizontal part. The latter is placed in the bile duct. The former, which is longer, carries the bile out of the body. The diameter of the tube varies, but is still in the range of a few millimetres. The bile ducts are vessels, a system of channels and ducts. The cystic duct ends with a sphincter that faces the ampulla of Vater. Its function is to transport bile from the common hepatic duct and the gallbladder to the ampulla of the Vater, where the bile produced by the liver reaches the intestines where it helps to digest food. There are conditions, including injury or the presence of a suture or anastomosis on the biliary tract, in which bile must come out of the biliary tract without passing through it, as it could leak from it and spread into the abdomen, causing serious complications such as collections, biliary peritonitis, dehiscence and leakage through surgical syntheses.
It is indicated for use in gallbladder and biliary surgery, including the treatment of iatrogenic biliary injuries during surgery, resective liver surgery and transplantation. The latter in particular represents a smaller proportion of activity than general abdominal surgery. In Italy, approximately 1,500 liver transplants are performed each year.
In most cases, the Kher tube is placed inside the bile duct through a small incision in the wall of the gallbladder. In liver transplantation, the T-tube is inserted just before the donor and recipient bile ducts join. The anastomosis is made by suturing the ducts together around their entire circumference. This suture line represents a point of least resistance and is subject to complications such as partial or total rupture of the anastomosis (dehiscence) with leakage of bile into the abdomen (cholestasis). If there are concerns about the tightness of the surgical sutures and the anastomosis on the biliary tree, the Kher tube allows time for the continuity of the biliary tree to re-establish itself, preventing the complications described above.
The long portion of the tube exits through a small incision in the wall of the recipient’s gallbladder; the shorter horizontal portion lies within the biliary tree. In the presence of the Kher tube, bile is forced into it by the pressure gradient. The Kher tube is connected to a collection bag placed at the foot of the patient’s bed. The difference in height between the patient, where the tube starts, and the floor, where the collection bag is, creates a pressure gradient that favours bile entering the tube rather than the bile duct. With the Kher tube, bile production can be monitored and controlled as an indicator of the functionality of the transplanted liver. The colour and amount of bile produced each day in the days following transplantation is an expression of the organ’s function. In the event of liver failure or rejection, the colour and quantity of bile produced is actually reduced or absent.
The Kher tube can also be used to inject a contrast agent during an X-ray examination (trans-kher cholangiography), which can be used to colour the walls of the bile duct and show the profile of the bile duct itself to detect obstructions or leaks along the bile duct.
After a variable period of time after placement (usually within a few months), the device must be removed. During its use in the patient, a mesh/sleeve of fibrotic cystic tissue is created which surrounds it throughout its course from the bile duct where it is inserted to the inner abdominal wall. When the tube is removed, the fibrous sleeve that has formed over these months cooperates and closes under the effect of positive abdominal pressure. Once the duct is closed, bile can only flow in its natural direction towards the intestine, rather than outwards as with the Kher tube.
The benefits of its use are numerous, as reported in the literature, but there are problems with its removal that make its use controversial even today.
It is removed by manual pulling, which requires some ‘muscle power’. Its T-shape is an obstacle to its exit from the bile duct. In fact, the entire horizontal section inside the bile duct must now pass through the small gap in the bile duct wall through which the long part of the tube exits. Where previously only the body of the tube passed through, the two overlapping arms of the stent must now pass through.
The forces involved in tube retraction can sometimes cause fracture/splitting of the structures involved. Such incidents have in some cases limited its use. Rare but still possible is the rupture of the Kehr tube within the biliary tract during its removal. The tube then remains in the abdomen and requires retrograde endoscopy (ERCP) or surgery to retrieve it, with the risks associated with these procedures.
Our design proposes a dismountable ‘T’ device with two pre-formed parts that slide into each other, making it easy to remove and reducing the risk of injury/rupture of the bile duct itself by minimising traction forces. This is the key point of our project: ‘facilitated removal’. In fact, in some cases, there is a tendency not to use it, even when its use could be useful, precisely to avoid possible damage related to its removal. We must also say that the decision to use the Kehr tube depends very much on the experience of the individual surgeon or transplant centre: there are centres that use it all the time, others that never use it, or others that use it when the graft comes from a ‘high-risk’ donor or in other specific circumstances.
If the device could be easily and safely removed from the bile duct at the end of its useful life, not only would many complications be avoided, but the procedure could be performed on an outpatient basis without the need for additional procedures such as surgery or ERCP.
In particular, in Udine (ASUFC), we perform the removal of the Kehr’s tube in liver transplant patients under endoscopic guidance. ERCP is a high-tech endoscopic procedure that requires sedation of the patient and must be performed in operating theatres with dedicated technical staff (doctor, nurse). A flexible tube is used to visualise both the extrahepatic bile duct (the choledoch, where the anastomosis of the transplanted liver and the Kehr’s tube are located) and the intrahepatic bile duct. Thanks to this examination, it is possible to follow the retraction manoeuvres of the Kehr’s tube and immediately highlight any leakage after removal of the device. In the event of a bile leak, ERCP can be used to place a prosthesis inside the bile duct, which acts like a ‘shirt’ to cover the bile leak.
The use of the Cherchi tube (named after the surgeon who developed it) can eliminate the cost of the entire procedure and any biliary prosthesis used, with significant overall economic savings, without subjecting the patient to an additional procedure under anaesthesia and reducing the length of hospital stay.
Finally, the Cherchi tube currently has to be left in place for up to 6 months, which is the time it takes for the fibrous scar to form around the tube. In the case of our “Easy Removal Drainage” model, this time would probably be shorter because, as mentioned above, there is minimal trauma to the biliary tract, so there is no need to wait for the complete formation of this “cuff” of scar tissue around the tube, which actually provides a natural safety system for its removal. However, we cannot say for sure because we need to study it further.
I mentioned Kehr’s tube in abdominal surgery because it is my speciality. In particular, I have been involved with the liver and pancreas since I became a specialist. But in general, the Kehr tube can be used in other areas of surgery because it can drain two different and distant areas by coming out of one hole in the skin, instead of using two different drainage tubes that would require two different holes in the skin. An example of further use could therefore be as an abdominal or neck drainage device after surgery in this area, or as a device in the treatment of gastric or oesophageal fistulas, as reported in some experiences in the literature.
Can you give us an indication of how many non-transplant surgeries it could be used for across the country?
This is a difficult question. Let us say that a few thousand hepatobiliary operations are performed in Italy every year. A number that increases if we include cholecystectomies or the removal of stones from the biliary tract, although they rarely involve the use of the Kehr tube. In this pool of procedures, I cannot really give you the numbers of its use, but certainly less than 5%. However, it is a difficult number to define.
Unlike transplants – which are registered by the CNT – Centro Nazionale Trapianti – abdominal surgery does not have a proper registry, so I do not want to venture into figures that have no confirmed scientific basis.
The figures for its use could be higher if you consider other applications in surgery. However, it could have other generic applications, such as abdominal drainage, which is used for many other surgeries. Or it could be scaled down to other sizes. For example, microsurgery. After all, surgery is also about draining fluids externally, so I think it can be used in many areas as a drainage tube. Ultimately, they act as sentinels, perhaps to highlight suspected bleeding or problems in the urinary tract. The principle of ‘take out’ applies to all surgical procedures. I have seen examples of the Kehr tube being used in cranioscopy to evacuate bleeding from the skull. I have also read some scientific studies on the subject. Just to say that there really is such a wide range of applications.
Project progress: current state of the art and plans for the future. What are you looking for?
The next step will be to develop the actual model. At the moment the project is little more than theoretical, as we have developed the first ‘Easy removal surgical T-drain’ models with the correct diameters and materials. So the mechanism works. But before we can use it on a patient, we need to get all the final parameters right. Of course, to do that you need the right technology to process/develop the details. You have to build it in a certain way, so you necessarily need the support of a company.
Spin-off or no spin-off? If no, why? If yes, with whom (investors/industrial partners?) How much would it take in economic terms?
Surely there would be room and potential. There are the right nuances, which for various reasons I have not yet been able to work out, to set something like this up. Undoubtedly there is a need for the hand of someone who can develop and speak the ‘language’, who can handle the business and market side of the project. Putting these ideas and studies into practice.
Would you be willing to become CEO of a possible spin-off if you could find industrial partners or investors to take the project forward?
I would say yes, because I see in this project the possibility of creating new funds for further research. In general, there are no funds for research. This would be a way to invest in research: mine, ours, of those who study and work to develop ideas. I see it as a way to do this and other things I am personally passionate about. Projects could be shared and networked with universities. Think about artificial intelligence applied to medicine. There are blended medical courses that include some computer science. We have reached a point where it is impossible to separate certain fields. That is why I believe that the surgeon, and medicine in general, needs to have someone immediately at their side – a consultant, a programmer, companies – with whom they can share the development of new technologies, tools or software.
If you were to start by building a first prototype to test, who would you need in terms of investors, companies, etc.?
Some companies have already come forward. We need someone who understands the potential of this work and has the right mentality to develop this project, which needs to be done with a certain quality. We don’t need to think about numbers, we need to think about the quality of the device. We need a company that is willing to develop and produce it with attention to materials and details. The companies that already produce the Kehr tubes, for example, could have the right technologies to develop this variant of ours.
Funding and biomedicine in Italy: your thoughts.
I think it is a project with all the potential to be supported nationally and beyond. I think the ‘strength’ of this project lies in its simplicity. Personally, I would urge support for ‘simple’ projects like this, which could represent the true scientific basis of patent research. Such solutions, by which I mean technologies and/or variations on traditional tools, could be applied in the immediate future and could have an important and decisive impact on health and healthcare.
Expectations and hopes for the Knowledge Share platform
Expectations are high. The Knowledge Share platform was created to bridge the gap between researchers and companies, two worlds that are often far apart. This project, a fundamental tool for bringing them together, facilitates the transition between the ideational and practical phases of business development, paying particular attention to bringing the two sides together in the most relevant way.
Discover the technology and contact the research team here: Easy removal surgical T-drain | Knowledgeshare (knowledge-share.eu)
Dott. Vittorio Cherchi – background and in-depth research to date
After graduating in medicine and surgery in Sassari, I decided to continue my studies and gain new experience outside the island. Udine was known for its excellent specialisation in general surgery – particularly in hepatobiliopancreatic surgery and liver transplantation. My final thesis was on exactly these topics. After 6 years of specialisation, I obtained my PhD, which allowed me to stay in Udine and work as a general surgeon and liver and kidney transplant surgeon. The idea for the new Kehr tube came from my experience in the fields of liver, resection and transplantation. It is a device with specific indications and advantages, the use of which can lead to complications in the biliary tract. In particular, its removal poses major problems that make its use controversial, especially in liver transplant patients. Excluding the problems associated with extraction procedures, its use could be fully useful and provide the expected clinical benefits of its presence in the biliary tract. The idea of a tube consisting of two sliding units seemed to be the most appropriate solution. The project was made possible thanks to the collaboration between Azienda Sanitaria Universitaria Friuli Centrale and the University of Udine and the work of Dr Giorgio Miclet, Dr Lorena Pizzale, Dr Marco Blanchini and Livio Petriccione. In addition, the instrument has undergone the stages leading to its recognition as a patent. Over the past year, several Italian and European companies have shown interest in the project. A first interaction with an Italian company has just taken place in order to jointly evaluate the implementation phase of the model and its subsequent development.