Abstract
Background Early detection of free flap compromise is critical for salvage of the flap. Various
methods of free flap monitoring have been described, but clinical assessment is the
standard method for among all. In this study, role of infrared thermography is evaluated
for free flap monitoring.
Materials and Methods In patients undergoing free flap surgery, monitoring was done using standard clinical
parameters and infrared thermography as per our institutional protocol. Mean temperature
difference (∆T) between the flap and the surrounding skin was calculated using the
temperature readings from the thermal images intra- and postoperatively. The accuracy
of infrared thermography in flap monitoring was assessed in comparison to the standard
clinical protocol.
Results Forty-one flaps were included in the analysis, out of which five flaps got compromised.
It was observed that the mean temperature difference was higher (mean ∆T 0.20–0.59
vs. 2.38–3.32) when there was a flap compromise, and this temperature difference was
evident even before the development of clinical signs. The temperature difference
in venous thrombosis (mean ∆T 1.0–2.7) was found to be slightly lower than in arterial
insufficiency (mean ∆T 2.1–4.4). For a ∆T cutoff value of 2°C, the thermal camera
had a sensitivity of 88.6%, specificity of 98.9%, positive predictive value of 93.9%,
and negative predictive value of 97.7%.
Conclusion Infrared thermography is a valuable and noninvasive objective tool in free flap monitoring,
which can detect flap compromise (increasing value of ∆T) even before it becomes clinically
evident.
Keywords
thermal imaging - free flaps - infrared thermography - free flap monitoring
