Is Hyperspectral Imaging Suitable for Assessing Collateral Circulation Prior Radial Forearm Free Flap Harvesting? Comparison of Hyperspectral Imaging and Conventional Allen's Test.

Diana Heimes,Solomiya Kyyak,Peer W Kämmerer,Robert Kuchen,Daniel G E Thiem,Philipp Becker

doi:10.3390/jpm11060531

Abstract

(1) Background: This cross-sectional study aims to compare a new and non-invasive approach using hyperspectral imaging (HSI) with the conventional modified Allen’s test (MAT) for the assessment of collateral perfusion prior to radial forearm free flap harvest in healthy adults. (2) HSI of the right hand of 114 patients was recorded. Here, three recordings were carried out: (I) basic status (perfusion), (II) after occlusion of ulnar and radial artery (occlusion) and (III) after releasing the ulnar artery (reperfusion). At all recordings, tissue oxygenation/superficial perfusion (StO2 (0–100%); 0–1 mm depth), tissue hemoglobin index (THI (0–100)) and near infrared perfusion index/deep perfusion (NIR (0–100); 0–4 mm depth) were assessed. A modified Allen’s test (control) was conducted and compared with the HSI-results. (3) Results: Statistically significant differences between perfusion (I) and artery occlusion (II) and between artery occlusion (II) and reperfusion (III) could be observed within the population with a non-pathological MAT (each <0.001). Significant correlations were observed for the difference between perfusion and reperfusion in THI and the height of the MAT (p < 0.05). Within the population with a MAT >8 s, an impairment in reperfusion was shown (each p < 0.05) and the difference between perfusion and reperfusion exhibited a strong correlation to the height of the MAT (each p < 0.01). (4) Conclusions: The results indicate a reliable differentiation between perfusion and occlusion by HSI. Therefore, HSI could be a useful tool for verification of the correct performance of the MAT as well as to confirm the final diagnosis, as it provides an objective, reproducible method whose results strongly correlate with those obtained by MAT. What is more, it can be easily applied by non-medical personnel.

Highlights

Licensee MDPI, Basel, Switzerland.The “Chinese flap”, the fascio-cutaneous radial forearm free flap (RFFF) was first described in 1981 by Yang et al [1,2]
hyperspectral imaging (HSI) could be a useful tool for verification of the correct performance of the modified Allen’s test (MAT) as well as to confirm the final diagnosis, as it provides an objective, reproducible method whose results strongly correlate with those obtained by MAT
It is used for diverse reconstruction purposes with a survival rate of 97% [3,4]; the popularity of its use has increased due to its pliability and thinness, the ease of flap raising using a two-team approach, a consistent anatomy, and the long and high-caliber vascular pedicle [1,2,3]

Summary

Introduction

The “Chinese flap”, the fascio-cutaneous radial forearm free flap (RFFF) was first described in 1981 by Yang et al [1,2]. It is used for diverse reconstruction purposes with a survival rate of 97% [3,4]; the popularity of its use has increased due to its pliability and thinness, the ease of flap raising using a two-team approach, a consistent anatomy, and the long and high-caliber vascular pedicle [1,2,3]. As the flap is vascularized by a segment of the radial artery that needs to be removed during the surgery, it is essential to published maps and institutional affil-.

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