Monitoring technologies for flap transplants

Flap transplantation — the transfer of a patient’s skin and tissue along with their native blood supply — is a standard method for repairing refractory wounds. While surgery has a clinical success rate of over 90%, it is crucial to monitor the recipient site within 72 hours post-operation, as 10% to 30% of patients experience vascular crisis, a complication that manifests quickly and can result in lifelong disabilities.

Fortunately, vascular crises come with early warning signs. Dynamic changes in flap temperatures, as subtle as a 1 C to 2 C difference from normal temperature, provide information on the microcirculation status of the transplant.

Hu et al. evaluated technologies that detect these changes.

“Existing monitoring methods are flawed, demonstrating poor real-time performance and low precision,” said author Tingting Hu. “We aimed to address this by systematically reviewing technologies to guide clinical practice.”

Among state-of-the-art technologies, infrared radiation thermometers, fiber optic sensing, and microwave sensing are most commonly used as early warning systems. The authors note the trade-offs of selecting each option, emphasizing the need to achieve precision, intelligence, and realistic integration into standard workflows.

They also examined the relationship between temperature and microcirculation complications. Venous crises and arterial crises, for example, impair blood flow at the flap in different ways and are marked by distinct temperature changes as they progress. A better understanding of such temperature microcirculation mechanisms guides future innovations like wearable sensors and artificial intelligence-driven monitoring systems. Both are topics the authors plan to explore.

“Our next work focuses on standardized wearable sensor calibration and interpretable multicenter artificial intelligence early warning models,” said Hu. “For others, key directions are low-cost miniaturized devices, multi-modal fusion monitoring, and large-scale, long-term studies to verify emerging technologies.”

Source: “Research progress in flap temperature monitoring technologies and applications after transplantation,” by Tingting Hu, Tao Yan, Junjie Chen, Qin Huang, Miao Cui, Yanting Han, and Ka Li, APL Bioengineering (2026). The article can be accessed at https://doi.org/10.1063/5.0314573 .

This paper is part of the Design, Integration, and Application of Intelligent Biomaterials Collection, learn more here .