Predicting intestinal viability by consecutive photoacoustic monitoring of oxygenation recovery after reperfusion in acute mesenteric ischemia in rats

The purpose was to assess whether consecutive monitoring of oxygenation by photoacoustic imaging (PAI) can objectively predict intestinal viability during surgery for acute mesenteric ischemia (AMI). PAI uses laser light to detect relative amounts of oxygenated and deoxygenated hemoglobin in intestinal tissue. In 30 rats, AMI was induced by clamping the mesenteric and marginal vessels of the ileum for 0 min in the control group, 30 min in the mild group, and 180 min in the severe group (10 rats per group). After 60 min of reperfusion, intestinal damage was evaluated pathologically. Oxygenation of the intestine was monitored throughout the procedure in real time by a commercially available PAI system and compared among the groups. All rats showed irreversible (i.e. transmucosal or transmural infarction) damage in the severe group. After reperfusion, the oxygenation in the mild group recovered immediately and was significantly higher than in the severe group at 1, 5, 10, 30, and 60 min (P = .011, 002, < .001, 001, and 001, respectively). Oxygenation showed a significant strong negative correlation with pathological severity (r(s) = − 0.7783, − 0.7806, − 0.7422, − 0.7728, and − 0.7704, respectively). In conclusion, PAI could objectively predict irreversible ischemic damage immediately after reperfusion, which potentially prevents inadequate surgery.