Photoacoustic imaging to monitor outcomes during hyperbaric oxygen therapy: Validation in a small cohort and case study in a bilateral chronic ischemic wound

AbstractDiseases of the microcirculatory system are well-known risk factors for chronic wound healing. Hyperbaric oxygen therapy (HBO2) is a common therapeutic modality that drives oxygen into hypoxic tissue to promote healing. Ischemia/hypoxia are common confounding variables associated with failure of wound progress and/or relapse, and hence it is important to develop tools that map and measure perfusion and oxygen saturation in the wound bed. Photoacoustic (PA) imaging is an ideal tool to address these concerns. Ten patients undergoing HBO2 underwent PA oximetry of the left radial artery and forearm pre- and post-HBO2; this cohort validated the use of PA imaging in HBO2. There was a significant increase in radial artery oxygenation after HBO2 (p=0.002) in the validation cohort. PA significantly underestimated arterial oxygenation compared to a pulse oximeter. We also include a case study: a non-diabetic male in his 50s (HB 010) presenting with bilateral ischemic and gangrenous wounds. HB 010 underwent additional scanning of the wound sites both pre- and post-HBO2. HB 010 showed higher perfusion and oxygen saturation on the right foot than the left after HBO2 which correlated with independent surgical observations. Imaging assisted with limb salvage treatment options by limiting the initial amputation site to only the toes. Hence, this work shows that PA imaging can measure changes in arterial oxygen saturation due to HBO2; it can also produce 3D maps of tissue oxygenation and evaluate response to therapy during HBO2.Key PointsPhotoacoustic oximetry can measure and map changes in arterial oxygenation due to hyperbaric oxygen therapy. Photoacoustic imaging shows changes in perfusion in a patient presenting with bilateral ischemic and gangrenous wounds and thus informing limb salvage treatment.