**5. Conclusions**

On average, evidence of critical flap perfusion occurred 4.8 h earlier in hyperspectral imaging when compared to clinical assessment. Therefore, our findings provide an interpretation aid for clinicians to simplify postoperative flap monitoring.

**Author Contributions:** Conceptualization, D.G.E.T. and P.W.K.; methodology, D.G.E.T., P.R. and S.B.; validation, D.G.E.T., P.R., S.B. and P.W.K.; formal analysis, D.G.E.T., P.W.K., P.R. and S.B., investigation, D.G.E.T., S.B. and P.R.; resources, D.G.E.T. and P.W.K.; data curation, D.G.E.T.; writing—original draft preparation, D.G.E.T., P.W.K. and B.A.-N.; writing—review and editing, D.G.E.T., S.B., P.W.K., B.A.-N. and P.R.; visualization, D.G.E.T.; supervision, D.G.E.T. and P.W.K.; project administration, D.G.E.T., P.W.K. and B.A.-N. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** The study was approved by the local ethic committee of Rhineland-Palate (registration-number: 2019-14312) and was conducted in accordance with the protocol and in compliance with the moral, ethical, and scientific principles governing clinical research as set out in the Declaration of Helsinki of 1975 as revised in 1983.

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** All raw data on which this study is based will be made available by the corresponding author upon request.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

