Sepsis? This plaster sounds the alarm when there is danger

Leaks in the sutures after an operation in the abdomen represent a life-threatening complication, for example if contents from the stomach or intestines get into the abdominal cavity. This can cause peritonitis or even dangerous blood poisoning. A newly developed polymer plaster should now warn of such dangerous leaks in the gastrointestinal tract in good time and close them independently, as a publication in “Advanced Science” shows.

So far, medical staff have mostly had to rely on the patient’s physical reactions, such as fever or laboratory tests, which may only provide indications of leaky sutures and serious complications such as sepsis at a late stage. The idea of ​​sealing sewn tissue with a plaster is already being used in operations.

Plaster is resistant to digestive juices

But how well this works varies depending on the type of tissue. Some of the patches used dissolve relatively quickly when they come into contact with digestive juices, for example. Researchers at the Swiss Federal Laboratories for Materials Science and Technology (Empa) and ETH Zurich have therefore developed a hydrogel polymer patch that is resistant to the acidic digestive juices or contents of the intestine and can prevent them from escaping through leaky seams. The patch is equipped with non-electronic sensors that “sound the alarm” before digestive juices enter the abdominal cavity.

The novel material reacts, for example, to changes in the pH value and detects specific proteins in the area surrounding the wound. Response occurs within minutes or hours depending on the location of the leak.

According to the researchers, when acidic gastric juice reacts with the sensor material, tiny gas bubbles form in the matrix of the patch. These bubbles can then be visualized using ultrasound. “The patches can be equipped with tailor-made sensors for different areas of the digestive tract,” explains Alexandre Anthis, who works both in the Particles-Biology Interactions laboratory at Empa in St. Gallen and in the Nanoparticle Systems Engineering laboratory at ETH Zurich.

Patch could even release drugs

In addition, the patch can even release drugs, such as antibacterial agents, if necessary, say the authors of the publication. They also describe another application: When it comes into contact with digestive fluid, the integrated sensor can change its shape from circular to ring-shaped due to a certain material composition. “A sensor whose shape clearly distinguishes itself from anatomical structures in the CT and ultrasound images could avoid ambiguities in the diagnosis in the future,” says Inge Herrmann, head of the team.

The functionality of the patch was proven in an experiment with pigs: it was applied to defective and intact stomach tissue sites, then CT images were taken at different times after the operation. Changes in the shape of the sensor element in the gastric leaks were already visible three hours after the procedure. The hydrogel patch, which was not in contact with gastric fluid, remained unchanged throughout the study period.

The material also fulfills the necessary properties for wound closure and a stable connection to the tissue. The patch, which is made mostly of water, could not only reduce the risk of complications after abdominal surgery, but also shorten hospital stays and lower healthcare costs, the researchers said. “The plaster project is already arousing great interest from the medical profession,” explains Inge Herrmann. Now it is important to promote the application in practice.