Early Detection of Vascular Obstruction in Microvascular Flaps Using a Thermographic Camera

Early Detection of Vascular Obstruction in Microvascular Flaps Using a Thermographic Camera

We read with great interest the article published by Cruz-Segura et al[1] regarding the free flap monitoring by the thermographic camera.

It is well known nowadays that an ideal free flap monitoring system does not exist. Such a system, as defined by Creech and Miller, should be noninvasive, rapid, accurate, reliable, and applicable to all types of flap.[2] We believe that the thermographic camera can provide real-time flap and surrounding skin temperature monitoring and that it can be used for assessment of vitality of extraoral and nonburied flaps only. For intraoral and buried flaps, however, the clinical evaluation (assessing color, capillary refill, temperature, and turgor) along with hand-held Doppler is still considered the standard of care, even though they depend on the surveyor's personal experience. Moreover, the sensitivity of the thermographic camera seems to be acceptable (>95%), while the specificity is supposed to be 80% only, leading to an estimated 20% rate of false negative results.[1] In addition, in the reported case series, only the type of flap used was listed in the table, while there is nothing written about the recipient area; the blood flow/blood pressure can vary depending on the anatomic site and a correlation stratifying the body area should be reported.

On one hand, the thermal camera system has the advantage of not being expensive but on the other hand, it is extremely sensitive to environment factors (i.e., environmental temperature) and patient's factors (blood pressure, systemic temperature, and patients' position). In addition, it cannot be used in buried flaps, as well as in intraoral reconstructions[3] (as it would be difficult, if not impossible to monitor the area[4]).

In our opinion, this type of monitoring system can be a helpful tool, especially when nonskilled surveyors are monitoring the free flap. The results will always need to be correlated with clinical signs (additional clinical monitoring). Further research and clinical studies are necessary for objective evaluation of thermographic camera used for monitoring free flaps.

• References

• 1 Cruz-Segura A, Cruz-Domínguez MP, Jara LJ. , et al. Early detection of vascular obstruction in microvascular flaps using a thermographic camera. J Reconstr Microsurg 2019; 35 (07) 541-548
• 2 Creech BJ, Miller SH. Evaluation of circulation in skin flaps. In: Grabb WC, Myers MB. , eds. Skin Flaps. Boston: Little Brown and Company; 1975
• 3 Cherubino M, Berli J, Turri-Zanoni M. , et al. Sandwich fascial anterolateral thigh flap in head and neck reconstruction: evolution or revolution?. Plast Reconstr Surg Glob Open 2017; 5 (01) e1197
• 4 Arnež ZM, Ramella V, Papa G. , et al. Is the LICOX PtO₂ system reliable for monitoring of free flaps? Comparison between two cohorts of patients. Microsurgery 2019; 39 (05) 423-427