Glowing bandage monitors oxygen uptake in transplanted tissue

Getting transplanted tissue to behave like the original tissue isn’t always a smooth process, and one of the things physicians look out for following a procedure is how well it takes in oxygen. Wired devices called oximeters are the gold standard when it comes to monitoring this in recovering patients, but scientists at Massachusetts General Hospital (MGH) may have found a better way forward in a paint-on bandage that glows in response to the levels of oxygen in the tissue.

Wired oximeters are the current go-to when it comes to monitoring tissue oxygenation, but these devices can be complex to use and are inconvenient for the patient, limiting their movement. So the MGH team sought to develop a less restrictive oxygenation sensor, which could help lower the rates of failed transplants and skin grafts.

The liquid bandage is made with phosphorescent materials that glow in colors ranging from red to green in response to certain stimuli. This prototype was tested out on five women undergoing breast reconstruction surgery, with the liquid bandage painted onto seven transplanted flaps that include skin, fat, arteries and blood vessels, in patches measuring 1 x 1 cm (0.4 x 0.4 in).

Also attached to these flaps were wired oximeters, as a means of comparing the performance of the liquid bandage alongside the gold standard. For these experiments, the team used a camera with a flash to excite the phosphorescent materials in the liquid bandage, which glowed from red to green depending on how much oxygen was present in the tissue.

After 48 hours of monitoring following the surgery, the team found the readings on each of the seven flaps provided by the bandage correlated with the readings from the oximeter. While just a proof-of-concept study with a small sample size and, the team imagines this oxygen-sensing bandage helping to improve the success rates of tissue transplants, skin grafts for burns and improving wound healing. In this way it is similar to a spray-on bandage for wound healing we looked at way back in 2014, which was also developed in part by senior author of the new study, Conor L. Evans.

“Our trial showed that the transparent liquid bandage detected tissue oxygenation as well as the gold standard of an oximeter, which uses old technology, is uncomfortable for the patient, obstructs visual inspection of the tissue, and can give false readings based on lighting conditions and the patient’s movements,” says Evans. “The standalone bandage is a major advancement from a wired oximeter that restricts a patient’s movements and is complicated to use.”

The researchers have since added a battery to the liquid bandage to make it self-powered and remove the need for a camera. They are now drawing up a clinical trial to explore how well the bandage can detect transplanted tissue that is failing due to a lack of oxygen.

The study was published in the journal Science Advances.

Source: Massachusetts General Hospital

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