Measurement of optical reflection and temperature changes after blood occlusion using a wearable device

Yingyi Xiao,Itsuro Saito,Mutsumi Okazaki,Yoko Tomioka,Masaki Sekino,Takao Someya,Koichi Kida,Jian Gu

doi:10.1038/s41598-020-68152-6

Yingyi Xiao, Itsuro Saito + Show 6 more

Open Access

https://doi.org/10.1038/s41598-020-68152-6

Copy DOI

Abstract

Early detection of compromised circulation is essential for postoperative monitoring of free flap. Hourly clinical check-ups such as inspection and palpation still result in a delay in detection. Conversely, optical reflection and temperature measurement are useful alternatives for detecting blood circulation. However, conventional methods that verify ischemia and congestion within a short period have not been reported. In this study, we measured short-term changes in optical reflection and temperature in a rat flap using a wearable flexible sensor probe previously developed in our laboratory. Five ischemia and five congestion groin flap models were measured using a sensor probe and reference devices. Curve fitting was performed on transition signals to evaluate changes in signals and their time constants. The optical reflection signal decreased after venous ligation and increased after arterial ligation. The parameters of the fitted curves indicate a significant difference between congestion and ischemia at p < 0.01 (probability value), which was detected within a few minutes after ligation. However, insufficient significance was observed in the temperature signal. Our method gives supporting information to verify ischemia and congestion, and has the potential to rapidly detect compromised circulation.

Highlights

MethodsThe system for measuring the optical reflection and temperature of skin tissue comprised a sensor probe, data transmitter, and tablet monitor, and was previously developed to measure pulse wave signals[34]
The optical reflection signal transition after arterial or venous occlusion is attributable to the change in arterial or venous blood volume, respectively
The arterial blood, venous blood and melanin decayed according to the Beer–Lambert Law ( Ix = I0e−μaL ), where Ix and I0 are the received and incident light intensity, respectively, μa is the absorption coefficient of tissue components, and L is the mean path length of light passing through the corresponding components

Summary

Methods

The system for measuring the optical reflection and temperature of skin tissue comprised a sensor probe, data transmitter, and tablet monitor, and was previously developed to measure pulse wave signals[34]. Four optical reflection sensors are marked by yellow boxes, temperature sensors are marked by red boxes, and A/D converters are marked by orange boxes. The optical reflection sensors on the probe were compact colour sensors (P12347, Hamamatsu Photonics, Japan), which were composed of RGB LED light sources, an Inter-Integrated Circuit (I2C) chip, and a colour sensing area.

Results

Discussion

Conclusion