Diagnostical Accuracy of Hyperspectral Imaging After Free Flap Surgery

Background: Microsurgical free-tissue transfer has been a safe option for tissue reconstruction in the last decades. Reliable perfusion assessments must be performed to increase the safety of the procedure and facilitate decision-making regarding postoperative reinterventions. Therefore, the present study analyzed the diagnostic accuracy of hyperspectral imaging (HSI) after free-tissue transfer surgery. Methods: : From January 2017 to October 2019, 42 consecutive free-flap surgeries were performed, and their outcomes were analyzed via HSI. Clinical examination of free-flap perfusion was initially performed. The clinical examination findings were subsequently compared with those of HSI. Next, decision-making and postoperative complications rates were analyzed. Potential venous congestion with subsequent necrosis was defined as a tissue hemoglobin index of ≥53%. To compare two sets of data a student’s t -test was used. The sensitivity and specificity for detecting flap failure were evaluated based on the dependence of time using the Fisher’s exact test. A p-value of ≤0.05 was considered statistically significant. Results: : The success rate of microsurgical tissue transfer was 83.2%. Seven patients presented with venous congestion, causing total flap necrosis. All flaps required additional surgery, debridement, and tissue reconstruction. 124 assessments were made. HSI accurately identified 11 out of 13 pathological images. Three images were identified as false positive and two images as false negative. The sensitivity and specificity of HSI were 84% and 97%, with the positive and negative predictive values of 78% and 98%, respectively. Conclusions: : A tissue hemoglobin index of ≥53% could predict a venous congestion after free-flap surgery within the first 72 h post operation. HSI could reasonably correlate with clinical observation. Until now, HSI does not show any superiority over any other monitoring modality.