*Article* **Free Myocutaneous Flap Assessment in a Rat Model: Verification of a Wireless Bioelectrical Impedance Assessment (BIA) System for Vascular Compromise Following Microsurgery**

**Yao-Kuang Huang <sup>1</sup> , Min Yi Wong 1,2, Chi-Rung Wu <sup>2</sup> , Yung-Ze Cheng <sup>3</sup> and Bor-Shyh Lin 2,3,\***


**Abstract:** Background: Microvascular tissue transfer is a common reconstructive procedure. We designed a bioelectrical impedance assessment (BIA) system for quantitative analysis of tissue status. This study attempts to verify it through the animal model. Methods: The flaps of the rat model were monitored by the BIA system. Results: The BIA variation of the free flap in the rat after the vascular compromise was recorded. The non-vascular ligation limbs of the same rat served as a control group. The bio-impedance in the experimental group was larger than the control group. The bio-impedances of both the **thigh**/**feet** flaps in the experimental group were increased over time. In the **thigh**, the difference in bio-impedance from the control group was first detected at 10 kHz at the 3rd and last at 1 kHz at the 6th h, after vascular compromise. The same finding was observed in the **feet**. Compared with the control group, the bio-impedance ratio (1 kHz/20 kHz) of the experimental group decreased with time, while their variation tendencies in the thigh and feet were similar. Conclusions: The flap may be monitored by the BIA for vascular status.

**Keywords:** flap grafting; microsurgery; biosensor; bioelectrical impedance; rat
