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Non-invasive monitoring of the transcutaneous partial pressure of oxygen (tcpO2) has great potential as the new standard of care in post-operative monitoring of autologous free flaps following cancer, trauma, or other reconstructive surgeries. Tissue perfusion and oxygenation are critical performance measures in the assessment of wound healing and graft monitoring; however, current clinical methods using near-infrared spectroscopy to probe the tissue’s oxygen saturation (StO2) from the local vasculature obscure the skin, require a wired hardware connection, and are ultimately an indirect measure. Herein we demonstrate how an optical liquid bandage, when painted on the flap skin paddle of four women undergoing a deep inferior epigastric artery perforator (DIEP) flap reconstruction after mastectomy, can be used to visualize tissue oxygenation using a simple commercial DSLR camera. Our transparent paint-on bandage formulation consists of New-Skin liquid bandage embedded with an oxygen-sensing metallo-porphyrin exhibiting bright red phosphorescence and a green-fluorescing reference dye, fluorescein. Red and green filtered photographs of the bandage were acquired for 48 hours post-operatively, and temporal changes in phosphorescence corresponding to tcpO2 were compared directly to StO2 readings obtained from a standard near-infrared tissue oximeter (ViOptix) placed on the same flap. Preliminary results show that the relative phosphorescence intensity reported by the liquid bandage inversely correlates with the stO2 values provided by the current gold standard of care, the ViOptix, as expected, while being substantially less obtrusive and enabling visualization of the flap beneath, even in patients with high melanin content, providing an additional advantage over current methods.
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