Real-Time VLS Detection of Colon Ischemia in AAA Repair

描述（由申请人提供）：该I期SBIR提案解决了检测与腹主动脉瘤（AAA）修复相关的结肠缺血的需求。50岁以上的成年人中有5%患有AAA。AAA修复的主要并发症是缺血（约5%的缺血发生在肠道和/或下肢）。在AAA修复过程中出现中重度结肠缺血的患者中，57%的患者死于不可逆性结肠梗死。手术干预可显著改善急性结肠缺血的预后，但前提是缺血能及早发现和治疗。然而，目前还没有fda批准的早期检测技术。

DESCRIPTION (provided by applicant): This Phase I SBIR proposal addresses the need to detect colon ischemia associated with the repair of Abdominal Aortic Aneurysm (AAA). AAA can be found in 5% of the adult population over 50. A leading complication of the repair of AAA is ischemia (about 5% rate of ischemia to the gut and/or lower limbs). Of the patients who develop moderate to severe colon ischemia during AAA repair, 57% die in hospital of irreversible colon infarction. Surgical intervention substantially improves the outcome of acute colonic ischemia, but only if the ischemia is detected and treated early. However, no FDA-approved early detection technique exists. We directly address this problem by seeking to detect colon ischemia early, prior to the onset of irreversible colon infarction. In this Phase I (R43) pilot trial we test the ability of a visible-light venous-oxygenation- sensitive rectal probe to detect acute colon ischemia during AAA repair. Such detection would ultimately allow for real-time vascular interventions already available to restore the colonic blood flow, reducing the lethality of acute colon ischemia. In this study, colon mucosal tissue hemoglobin saturation (StO2%) is measured with a rectal catheter that monitors hemoglobin in the small blood vessels (arterioles, capillaries, and venuoles) using shallow-penetrating, highly-localizing visible light (green to orange), allowing localized mucosal measurement. This approach differs from most optical methods by using shallow- penetrating visible light spectroscopy (VLS) that permits mucosal oxygenation monitoring via thin catheters. The specific aims of Phase I (R43) are (a) To monitor 20 patients undergoing AAA repair to establish normal StO2% values in patients with vascular disease, (b) to cross-validate VLS StO2% against laser Doppler measures of local blood flow, and (c) to modify the hemoglobin algorithm to include the pigmented urobilinogen breakdown products of heme in the stool to test if this reduces the influence of residual stool in the field and results in >2 % mean saturation difference. Later, when these milestones are met, we will submit a follow-on Phase II (R44) trial in which we test the catheter at 5 centers in a clinical test of catheter safety and efficacy in patients undergoing AAA repair. If successful, this grant will result in a manufacturable device to reduce the mortality of colon ischemia during AAA repair, by allowing for intervention at the onset of ischemia, prior to progression to colon death.