Post-operative monitoring of free flaps using a low-cost thermal camera: a pilot study

S Hummelink,W Steenbergen,D J O Ulrich,A S Kruit,A R W Van Vlaenderen,M J M Schreinemachers

doi:10.1007/s00238-020-01642-y

Abstract

BackgroundCareful post-operative monitoring of free flaps is important in flap survival; immediate action increases flap salvage rate. Although various methods are available, room for improvement remains. Thermal cameras have proven their value in medicine and are nowadays readily available at low costs. The objective of this study was to evaluate the potential of an affordable infrared thermal camera and software in the detection of failing free flaps during post-operative monitoring.MethodsFree myocutaneous rectus abdominis flaps were harvested in 16 female landrace pigs and replanted after several hours of storage. All flaps were assessed with indocyanine green fluorescence angiography as well as hourly clinical assessment of skin colour, turgor and capillary refill. Furthermore, thermal photographs were taken simultaneously with the FLIR One thermal camera smartphone module. These photographs were processed in MATLAB and evaluated on their additional value as an indicator for flap failure.ResultsOut of 16 flaps, three flaps failed due to arterial failure and one flap developed venous congestion. The mean flap temperature compared to adjacent control skin proved to be most indicative for flap failure. All unsuccessful flaps showed lower temperatures after failure compared to the uncompromised free flaps.ConclusionsAn affordable thermal camera module can potentially contribute to post-operative free flap monitoring. Vascular compromise in free flaps can be distinguished by investigating relative temperature differences between the flap and reference skin. Until the FLIR One camera has been extensively investigated in a human population, it should be used in conjunction with conventional monitoring techniques.Level of evidence: Level IV, diagnostic study

Highlights

Over the last decades, free tissue flaps have been extensively used for the reconstruction or coverage of large defects following trauma, burns, infection and tumour extirpation [1]
More technologically advanced methods such as handheld or implantable Doppler ultrasonography, tissue oximetry like non-invasive oxygen saturation via near-infrared spectroscopy (NIRS) or minimally invasive tissue oxygen tension have been practiced over the past years [7,8,9,10]
There is a continuous search for better monitoring techniques during the first crucial 72 h after free flap transfer

Summary

Introduction

Free tissue flaps have been extensively used for the reconstruction or coverage of large defects following trauma, burns, infection and tumour extirpation [1]. More technologically advanced methods such as handheld or implantable Doppler ultrasonography, tissue oximetry like non-invasive oxygen saturation via near-infrared spectroscopy (NIRS) or minimally invasive tissue oxygen tension have been practiced over the past years [7,8,9,10]. As each of these methods offers both advantages and disadvantages, room for improvement remains. The objective of this study was to evaluate the potential of an affordable infrared thermal camera and software in the detection of failing free flaps during post-operative monitoring

Objectives

Methods

Results

Discussion

Conclusion