A prospective clinical trial comparing visible light spectroscopy to handheld Doppler for postoperative free tissue transfer monitoring

BACKGROUND:: Early detection of compromised free flap perfusion is critical. A common modality of thrombosis detection, physical exam augmented with hand-held Doppler, only provides intermittent data and is insensitive to venous compromise. Visible light spectroscopy (VLS) provides continuous, non-invasive evaluation of tissue perfusion. We hypothesized that VLS is a more sensitive and specific monitoring method for early detection of post-operative flap compromise than intermittent, hand-held Doppler and clinical exam. METHODS:: We prospectively conducted a controlled study evaluating the sensitivity, specificity, and accuracy of the T-Stat Model 303 VLS oximeter (Spectros Corp., Portola Valley, CA) versus that of intermittent Doppler and clinical exam. We prospectively collected and analyzed patient data, complications, reoperations, flap failures, and tissue oxygen saturation (StO2). RESULTS:: Sixty-eight patients with 81 flaps completed the study. The majority of flaps (86.4%) were either transverse rectus abdominis musculocutaneous or deep inferior epigastric artery perforator flaps. The mean StO2 for all flaps in the study was 56.7±7.1% (range = 39.4-72.1%) and did not differ significantly with patient comorbidity or flap type. During the course of the study, three flaps were returned to the operating room for exploration due to a perfusion abnormality, and the resulting salvage rate was 100%. The sensitivity, specificity, and accuracy of VLS were found to be greater than both intermittent Doppler and clinical exam. CONCLUSION:: VLS is a reliable, continuous adjunct to free tissue transfer monitoring with advantages over intermittent hand-held Doppler and clinical exam.