Norwegian researchers successfully tested a respiratory stent that was completely removed without significant technical or medical complications, in a proof-of-principle animal study.
Two years ago, Dr Erney Mattsson from the Norwegian University of Science and Technology (NTNU) launched a new type of stent for use in blood vessels. Now he and his colleagues are in the process of attempting to use the same type of stent in the respiratory tract.
A stent is a cylindrical mesh tube that can be placed in arteries or in the lungs to open blockages or areas that are narrow or weak. Traditional stents work well, but have the disadvantage that they must remain in the body. NTNU researchers are now testing the new kind of stent to see how it can be used in the lungs.
This new type of stent can be removed and the advantages of this are clear, Mattsson says. "That's because a foreign object causes the body to react so that the vessel narrows again. The best is if we can simply remove the stent after it has done its job," he said.
Mattsson evaluated and tried several different methods, but he found the ultimate solution in a pair of old socks. Mattsson's stent is knitted, and like a sock can be unraveled after it has been used. This allows the stent to be removed when it is not needed anymore.
"It sounds simple once you know about it, but basically we tried different ways of removing stents. But it wasn't until I saw a pair of old-fashioned rag socks that I had an Eureka moment. So that was it," he said. "All we have to do is leave a thread sticking out, and then we have to have a hold on the stent. Then we pull the thread and the stent unravels, and gets smaller and smaller."
Mattsson's colleague and collaborator Tore Amundsen says the stent can be used in pulmonary medicine, especially in patients who are short of breath due to narrowing of the airways, especially in the central respiratory tract. This may be caused by lung cancer or narrowing of the airways from cancer that has spread from other organs to the lungs or airways.
The collaborators have already wondered if the stent could also be used to allow surgeons to do surgery via the airways. "Being able to use a stent like this to temporarily open access to small tumors will be of great importance. And then you can avoid doing open surgery," Amundsen said.
Abstract
Background: Malignant airway obstruction is a feared complication and will most probably occur more frequently in the future because of increasing cancer incidence and increased life expectancy in cancer patients. Minimal invasive treatment using airway stents represents a meaningful and life-saving palliation. We present a new removable airway stent for improved individualised treatment.
Methods: To our knowledge, the new airway stent is the world’s first knitted and uncovered self-expanding metal stent, which can unravel and be completely removed. In an in vivo model using two anaesthetised and spontaneously breathing pigs, we deployed and subsequently removed the stents by unravelling the device. The procedures were executed by flexible bronchoscopy in an acute and a chronic setting – a ‘proof-of-principle’ study.
Results: The new stent was easily and accurately deployed in the central airways, and it remained fixed in its original position. It was easy to unravel and completely remove from the airways without clinically significant complications. During the presence of the stent in the chronic study, granulation tissue was induced. This tissue disappeared spontaneously with the removal.
Conclusions: The new removable stent functioned according to its purpose and unravelled easily, and it was completely removed without significant technical or medical complications. Induced granulation tissue disappeared spontaneously. Further studies on animals and humans are needed to define its optimal indications and future use.
Authors
Tore Amundsen, Sveinung Sørhaug, Håkon Olav Leira, Stig Sverre Tyvold, Thomas Langø, Tommy Hammer, Frode Manstad-Hulaas, Erney Mattsson
[link url="https://www.sciencedaily.com/releases/2017/01/170112083731.htm"]Norwegian University of Science and Technology material[/link]
[link url="http://www.ecrj.net/index.php/ecrj/article/view/30010"]European Clinical Respiratory Journal abstract[/link]