Thermal diffusion probe analysis of perfusion changes in vascular occlusions of rabbit pedicle flaps.

Background: The purpose of this study was to show the efficacy of a novel tissue blood flow measuring device in an animal model. Thermal diffusion technology evaluates changes in perfusion in small volumes of tissue.

Methods: The thermal diffusion probe device is a long, 0.9-mm-diameter flexible catheter with two thermistors, which are placed directly into the tissue; it excites an active thermistor to a constant temperature slightly above the tissue baseline and collects data on the power dissipated in the active thermistor. It also continuously monitors the baseline tissue temperature using an additional passive thermistor placed outside the heated field. In this study, rabbit epigastric pedicle flaps were instrumented with two thermal diffusion probes (peripheral and deep) to continuously monitor flap perfusion.

Results: Twenty-five vascular occlusion studies were performed in 16 flaps. Blood vessel occlusions (arterial, venous, and arteriovenous) were easily detectable with this system. Waveforms for arterial and arteriovenous occlusions differed from those for venous occlusions. Probes in both peripheral and deep tissue locations were sensitive to changes in tissue perfusion.

Conclusion: Thermal diffusion probes may provide a useful clinical method for monitoring flap perfusion.