Alleviating A Sticking Point in Patient Monitoring

Despite the numerous examples of life-saving advanced technology that are available to today’s healthcare providers, there are certain limitations that persist and pose vulnerabilities to specific patient populations. One such example is the limited capabilities among many of today’s monitoring-type devices, particularly related to those that aim to detect changes deep within tissues. The reasons for this vary, according to John A. Rogers, PhD, SM, BS, BA, a professor of materials science and engineering, biomedical engineering, and neurological surgery at Northwestern University.

“Attenuation in biological tissues limits the detection range of many existing devices to shallow depths, while approaches capable of detecting changes in deep tissues, such as CT, X-ray or biopsies, are often high-cost, invasive, and not compatible with continuous detection,” said Rogers, who, along with colleagues at Northwestern and Washington University School of Medicine, has recently developed a novel shape-shifting sticker that enables healthcare providers to monitor the health of deep tissue and organs when used in tandem with ultrasound.

Clinicians are able to view shifts in shape that occur with the tiny stickers in real time through ultrasound imaging when the devices are attached to any organ in response to bodily changes in pH levels. This can serve as an early warning sign for post-surgery complications such as anastomotic leaks, according to a recent report about the stickers released by Northwestern. The report also claims that no existing methods can reliably and non-invasively detect life-threatening anastomotic leaks that occur when gastrointestinal fluids escape the digestive system. The stickers are seen as a way to enable earlier intervention than previously considered by revealing the leakage of these fluids with high sensitivity and high specificity. The biocompatible, bioresorbable, noninvasive BioSUM dissolves when patients are fully recovered, which bypasses the need for surgical extraction, according to the report.

These stickers can also reveal specific types of leaks even when the leaks occur in deep body locations, said Rogers, who co-authored a study related to the stickers in the March 8 edition of Science. “As demonstrated in small and large animal models that illustrate capabilities in monitoring leaks from the stomach, the small intestine, and the pancreas, the ultrasound stickers reveal anastomotic leaks by ultrasound imaging,” he told MD+DI.

While Rogers also said that further validation in rigorous clinical trials will be necessary to develop a product that would be deemed suitable for human use, there is excitement building about the future prospects of these stickers. The recently published study, “Bioresorbable shape-adaptive structures for ultrasonic monitoring of deep-tissue homeostasis,” outlines evaluations that reportedly validate three different types of stickers made of hydrogel materials that are tailored for the ability to detect anastomotic leaks. The study was supported by the National Science Foundation, the National Cancer Institute, and the Querrey-Simpson Institute for Bioelectronics.

Device functionality

Designed and sized to allow for deployment by syringe injection or laparoscopic surgery, the BioSUM (or Bioresorbable, Shape-adaptive, Ultrasound-readable Materials) implants demonstrate high visibility in their non-invasive imaging and are compatible with portable ultrasound patient monitoring that’s utilized in the home setting. The stickers introduce paper-thin metal disks that are embedded into thin layers of the hydrogel matrix to transduce their shape changes to strong contrast and visibility in ultrasound images, reflecting physically or chemically specific parameters in deep tissues. The stickers swell if they encounter leaked fluids. When the hydrogel swells in response to changing pH, the metal disks move apart. These subtle changes in placement can be viewed by ultrasound.
“The ultrasound stickers change their shape in response to fluctuations of physiological parameters, specifically pH, inside the body through a recovery period, which can be monitored in real-time by ultrasound imaging,” Rogers explained. “The result serves as an early warning sign in postoperative complications. After a clinically relevant timeframe, the stickers resorb into the body, eliminating the need for extra hospital visits and surgical interventions. We developed algorithms for automatic image analysis and assessment of the device with high accuracy, so patients and physicians do not need to be trained to interpret the images. Potential integration with machine learning in the future may further improve the process.”
All three types of the BioSUM provide real-time monitoring of pH fluctuations deep inside the body based on ultrasound imaging, according to Rogers. “Their soft, flexible, and thin designs are compatible with minimally invasive surgeries,” he said. “The device-specific designs are tailored to operate across relevant ranges of pH values that cover the entire GI tract and are capable of detecting different types of anastomotic leaks timely and accurately.”

Patient benefits and future progressions

While these devices support a noninvasive approach to detecting potential anastomotic leaks after GI surgeries in their current format, Rogers believes that a minor extension of the platform technology could allow for the monitoring of other postoperative complications throughout a recovery period in patient care moving forward. “Ultrasound stickers with similar concepts may enable the detection of additional physically or chemically specific parameters, such as temperature or internal bleeding,” he said. “This platform is extendable to monitoring other clinically relevant signals by altering the design of the shape-changing materials.”