Usage of VIS spectroscopy for in-vivo evaluation of bowel vitality in acute mesenteric ichemia in clinical studies

Objective: This study aimed to investigate the effectiveness of the visible region (VIS) spectroscopy method in evaluating the viability of intestinal segments during surgery to determine the resection line at laparotomy in patients with suspected acute mesenteric ischemia (AMI). Method: VIS diffuse reflectance spectra were acquired from the healthy bowel regions, ischemic bowel regions, and anastomosis lines during the surgery of seven patients who underwent diagnostic laparotomy. Then, hemoglobin absorption spectra were obtained from the VIS spectra of each patient. It was observed that the ratio of the absorption value at 577 nm to the absorption value at 560 nm varied between the absorption spectra obtained in ischemic and healthy tissues. Therefore, the A(577)/A(560) ratio was chosen as a parameter correlated to tissue oxygenation saturation. First, the ratios were obtained for the healthy areas, ischemic areas, and surgical lines to evaluate the decrease in tissue oxygen saturation (%DStO2) at the ischemic tissues. Then, a correlation between the %DStO2 and histopathology results of the ischemic tissues was investigated, where histopathology results were accepted as the gold standard. Results: A statistically significant correlation was obtained between DStO2% and Ciu scores of the ischemic tissues. (P=0.001). Based on the histopathologic examination, considering the integrity of the intestinal tissue and self-repair, it was decided to have a Chiu score of 3 at the intestinal resection line where DStO2% was 25.7±7%. Therefore we defined DStO2%= 25.7±7% as a threshold value for the resection line. Conclusion: VIS diffuse reflectance spectroscopy has the potential to provide objective criteria to define the surgical margin of the intestine tissue in acute mesenteric ischemia based on DStO2% in real-time. Keywords: diffuse reflectance spectroscopy, acute mesenteric ischemia, absorption spectrum, tissue oxygen saturation