Background: The differentiation of "viable" from "nonviable" bowel remains a challenge in the treatment of acute mesenteric ischemia. In this study, diffuse reflectance spectroscopy (DRS) was used to investigate the viability of bowel tissue after ischemia and reperfusion in an animal model in vivo and in real time.
Methods: A total of 25 females Sprague-Dawley rats were divided into five groups based on different bowel ischemia times. In each study group for four of them, the superior mesenteric artery was occluded using a vascular clamp for a different period (i.e., 30, 45, 60, and 90 min; n = 5 for each group). Intestinal reperfusion was accomplished by releasing the clamps after the given occlusion period for each group. Spectra were acquired by gently touching the optical fiber probe to the bowel tissue before the induce ischemia, at the end of the induced ischemia, and after the reperfusion. The data acquired before the ischemia were used as a control group. Without occluding the superior mesenteric artery, the spectra were acquired on the bowel with the same time intervals of the experiments were used as a sham group (n = 5). Subsequently, the same bowel segments were sent for histopathologic examination.
Results: Based on the correlation between the spectra acquired from the bowel segments and the results from the histopathologic investigation, DRS is able to differentiate the histopathologic grading that appears when the Chiu/Park score ≥5 (i.e., high-level ischemic injury) than Chiu/Park score <5. Eight out of nine low-level ischemic injury tissue samples were correctly defined using the spectroscopic classification system. All eleven high-level ischemic injury tissues that were histopathologically assigned grade 5 and above were correctly defined using the spectroscopic classification system in the ischemia-reperfusion groups.
Conclusions: DRS could potentially be used intraoperatively for the assessment of bowel viability in real time. These preliminary findings suggest that DRS has the potential to reduce unnecessary resection of viable tissue or insufficient resection of nonviable tissues may reduce the mortality and morbidity rates of intestinal ischemia-reperfusion as acute mesenteric ischemia.
Keywords: Acute mesenteric ischemia; Intestinal tissue viability; Intraoperative; Ischemia–reperfusion; Real time; Reflectance spectroscopy.
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