Tissue oxygen saturation measurements by using optical fiber spectroscopy: Assessment of free flap perfusion

The free flap is a unit of tissue and is transferred from one site to another with the aim of improving form and function while maintaining its own blood supply. A perfusion with sufficient tissue oxygenation is important for the survival of free flaps. The gold standard method for monitoring free flap has yet to be established. Many failing free flaps can be salvaged with early identification and prompt intervention. Therefore clinicians underscores for the importance of reliable postoperative flap monitoring. The aim of this study is to develop a spectroscopic system running non-invasive in real time to measure local tissue oxygen saturation in vivo and to investigate the sensitivity and specificity of the method in postoperative flap viability monitoring. The experimental set up for the spectroscopic measurements was consists of a miniature spectrometer, a fiber optical probe, a halogen-tungsten light source and a laptop. In the study, human blood samples with different level of oxygen saturations have been prepared and spectra were acquired using a fiber optical probe to investigate correlation between the oxygen saturations and the spectra. Then this method was used to determine tissue viability in postoperative flap cases. The results suggested that fiber optical spectroscopy is a sensitive method to estimate the StO₂ levels in vivo. The technique developed to measure tissue StO₂ has potential to improve bedside monitoring device for assess tissue perfusion and follow up prognosis of flap.