An interdisciplinary partnership finds an engineering solution to a clinical problem.
“This work is a great example of a fruitful multidisciplinary collaboration, and the importance of leveraging both engineering and clinical expertise to solve real-world problems.”
Dr. Babak Shadgan (pictured above)
Dr. Babak Shadgan first met Dr. Donald Anderson as a patient. After a routine medical procedure, Dr. Anderson noticed that Dr. Shadgan had applied a miniature, non-invasive near-infrared spectroscopy (NIRS) device to the surgical site to monitor tissue oxygenation and ensure proper healing. In that moment, Dr. Shadgan demonstrated a solution to a problem that had long challenged Dr. Anderson, and a collaboration was born.
During reconstructive surgery for cancer resection or major soft-tissue trauma, surgeons take a free flap of tissue from the leg, forearm, or shoulder and graft it onto the defect site to restore coverage and reestablish perfusion (blood flow). Successful vascularization during the first 72 postoperative hours is critical for initiating repair of bone and soft tissue. Although free-flap reconstruction is common and generally effective, flap failure still occurs in 5–25% of cases due to compression, thrombosis, infection, or mechanical reinjury.
For the first 72 hours after surgery, nurses monitor the site for visual and tactile signs of compromised perfusion. If vascular failure is missed or detected late, the flap becomes non-viable, requiring debridement of necrotic tissue, wound enlargement, and repeat grafting. Each additional surgery increases morbidities, prolongs hospitalization, and complicates recovery.
Dr. Shadgan, a medical doctor and biophotonics scientist, is an Assistant Professor in the Department of Orthopaedics and an Associate Faculty Member at the UBC School of Biomedical Engineering. He is a Principal Investigator at ICORD, leading the Implantable Biosensing Laboratory, where his team develops biosensors for clinical monitoring and diagnosis. In collaboration with Dr. Anderson, Clinical Professor with UBC’s Department of Surgery, he created a non-invasive free tissue transfer (FTT)-NIRS monitoring system that delivers real-time updates to nursing staff and physicians, and alerts care teams when flap status changes.
“When tissue oxygenation drops below a predefined threshold, the system sends a notification to the nursing station or to the clinician directly, indicating that something is wrong,” said Dr. Shadgan.
Once placed at the surgical site, the FTT-NIRS probe emits near-infrared light up to 2 cm into the tissue. Optical sensors monitor changes in blood oxygenation and hemodynamics, while the FTT-NIRS algorithm analyzes light absorption by oxygenated and deoxygenated hemoglobin. These data indicate whether tissue oxygenation or circulation is becoming compromised (Figure 1).
To evaluate the device, Shadgan and Anderson applied the sensors to patients following head and neck free-flap surgeries, supplementing standard clinical monitoring. The sensor preserved tissue flaps in approximately 85 percent of at-risk cases, compared to 48 percent with standard clinical exams.
“We were encouraged when a student, monitoring the sensor data overnight, noticed that oxygen levels (Tissue Oxygenation Index – TOI%) in a patient’s surgical flap had dropped,” said Shadgan. “The student was able to alert the nursing station, and a nurse was able to check the patient and discovered that during sleep, the patient had rolled onto the surgical site, causing tissue compression, resulting in a dip in blood flow.”
“Nurses were able to reposition the patient, which restored circulation at the surgical site,” said Shadgan (Figure 2). “The next morning, we heard from the surgeon that the tool had worked as intended, keeping the patient out of additional surgeries. The patient, as well, when he heard about this, got very excited that it had worked, and he was very happy.”
Encouraged by these results, Dr. Shadgan and his colleagues are optimistic about the tool’s potential for organ transplants and for monitoring trauma-related tissue injuries. His team is now developing a wireless version to enhance clinical usability.
“After those early conversations with Dr. Anderson, I looked through the literature and realized that we were looking at an unmet need. It took the two of us, with our very different perspectives on the issue, to advance a solution,” said Dr. Shadgan, who was able to access resources available to researchers, including a VCHRI award and CIHR funding to pursue the project. “This work is a great example of a fruitful multidisciplinary collaboration, and the importance of leveraging both engineering and clinical expertise to solve real-world problems.”
This project is supported by a CIHR Project Grant, and research is ongoing at VGH and Surrey Memorial Hospital.