Application of photoacoustic tomography in monitoring oxygen metabolism status of local tissues during surgical operation

In many surgical procedures, the objective is to restore tissue oxygenation and achieve effective revascularization. However, methods for evaluating tissue perfusion and oxygen metabolism are limited. Current clinical approaches mostly assess the patient's overall oxygen saturation level and lack a non-invasive, real-time method to evaluate local hypoxia during surgery. In this study, New Zealand white rabbits were first anesthetized and endotracheally intubated. The experiment began with oxygen supply being suspended for five minutes to establish a rabbit model of hypoxia. Subsequently, synchronous blood gas analysis and photoacoustic imaging tests were conducted on the carotid and femoral arteries of the rabbits. Blood gas analysis showed that the carotid arterial oxygen saturation of three rabbits was 100% before oxygen deprivation; after a five-minute cessation of oxygen, the carotid arterial oxygen saturation decreased to 3.6% ± 1.5%, with a rapid initial decline followed by a slower rate. Photoacoustic imaging results indicated that the oxygen saturation in the femoral arteries of the three rabbits dropped sharply from 100% to below 10% at the moment of oxygen deprivation, while muscle oxygen saturation fell from around 90% to below 30%. The trend of change was consistent with arterial oxygen saturation, but with a slightly smaller amplitude. This study validates that photoacoustic imaging technology can accurately reflect changes in vascular and tissue oxygen saturation within the body during hypoxic conditions, and due to its capability for localized detection and non-invasive real-time monitoring, it holds promise for future use in assessing anastomotic patency in revascularization surgeries.