Exploring Near Infrared Spectroscopy (NIRS) technologies for assessment of muscle physiology, tissue oxygenation, and blood flow in patients with Sickle Cell Disease (SCD

镰状细胞病（SCD）是一种遗传性血红蛋白病，不成比例地影响美国的少数民族人口，影响约10万人，主要是非洲血统，每365名非洲裔美国人中就有1人出生。β珠蛋白的第6位氨基酸上的缬氨酸被谷氨酸取代导致异常血红蛋白变体（HbS），其一旦脱氧就聚合，并改变红细胞（RBC）的结构和功能，使其变形为奇异的镰刀形状。镰状红细胞的寿命是正常的1/6，导致慢性溶血性贫血;它们也是刚性的，可以阻塞微血管血流，导致反复出现的不可预测的急性血管闭塞性疼痛周期，通常称为血管闭塞性危象（VOC）。反复发作的挥发性有机化合物导致缺氧再灌注损伤，并与血管内溶血一起促进炎症和血管内皮损伤。这种全身性血管病变影响多个器官，导致心血管并发症、慢性疼痛、脑和肾损害。 近红外光谱（NIRS）是一种无创光学技术，用于表征微血管血流动力学，包括血红蛋白浓度，血流量和组织氧饱和度。有大量文献报道了近红外光谱在乳腺癌和运动科学等各种临床应用中的应用。鉴于SCD相关的微血管血流和内皮功能障碍的损害，高级定量NIRS是在床旁环境中提供全面血流动力学评价的有吸引力的候选者。在SCD中评价NIRS器械的研究有限。一项研究报告了肱袖带闭塞后相对减弱的充血反应，表明SCD患者的内皮功能障碍。从另一项研究中获得的初步数据令人鼓舞，并表明收集的血流动力学信息与临床实验室值相关。 在这项单中心、非干预性、探索性研究中，40名受试者（20名SCD（HbSS和/或HbSB 0）和20名健康对照（HbAA））将作为门诊患者使用NIRS应用程序和方案接受基线血流动力学评估。 可邀请一部分研究受试者定期返回临床中心进行临床和NIRS再评估，在初始（基线）访视后120天内进行最多4次额外访视，间隔至少3天，以检测NIRS的重复性。 本研究的目的是与健康对照组的数据相比，进一步生成SCD中的NIRS衍生组织血流动力学数据。这些数据将有助于提供最合适和最有效的光学技术，最好地区分SCD患者的异常血流动力学与健康对照组的正常生理变化。最佳的近红外光谱技术，然后可以采用和应用于SCD患者的定期筛查和疾病监测。迄今为止，共入组了19例受试者（13例SCD和6例HbAA）

Sickle cell disease (SCD) is an inherited hemoglobinopathy that disproportionately impacts minority populations in the United States affecting about 100,000 individuals, primarily of African ancestry, and 1 in 365 African-American births. The substitution of valine by glutamic acid on the 6th amino-acid of beta globin results an abnormal hemoglobin variant (HbS) which polymerizes once deoxygenated, and alters both the structure and function of red blood cells (RBCs) distorting them into bizarre sickle shapes. Sickled RBCs have a lifespan 1/6th that of normal, resulting in chronic hemolytic anemia; they are also rigid and can obstruct microvascular blood flow causing recurring, unpredictable cycles of acute vaso-occlusive pain, commonly referred to as vaso-occlusive crises (VOC). The recurrent VOCs lead to hypoxia-reperfusion injury and together with the intravascular hemolysis promote inflammation and vascular endothelial damage. This systemic vasculopathy affects multiple organs leading to cardiovascular complications, chronic pain, cerebral and kidney impairment. Near infrared spectroscopy (NIRS) is a non-invasive optical technique for characterizing microvascular hemodynamics including hemoglobin concentration, blood flow, and tissue oxygen saturation. There is a wealth of literature reporting on NIRS in a wide variety of clinical applications including breast cancer and exercise science. Given the impairments to microvascular flow and endothelial dysfunction associated with SCD, advanced quantitative NIRS is an attractive candidate to provide comprehensive hemodynamic evaluations in point-of-care settings. There are limited studies evaluating NIRS devices in SCD. One study has reported a relatively dampened hyperemic response after brachial cuff occlusion, indicative of endothelial dysfunction in SCD patients. The preliminary data obtained from another research study are encouraging and demonstrates that hemodynamic information collected correlates with clinical lab values. In this single site, non-interventional, exploratory study, 40 subjects (20 SCD (HbSS and/or HbSB0) and 20 healthy controls (HbAA)) will undergo a baseline hemodynamic assessment as outpatients utilizing NIRS applications and protocols. A subset of study participants may be invited to return to the Clinical Center for clinical and NIRS reassessment periodically for a maximum of 4 additional visits, at least 3 days apart, within 120 days from their initial (baseline) visit to test for repeatability of the NIRS. The purpose of this study is to generate further NIRS-derived tissue hemodynamic data in SCD compared to data from healthy controls. The data will help inform the most appropriate and efficient optical technique that best differentiate the abnormal hemodynamics in SCD patients from normal physiological variation in healthy controls. The optimal NIRS technique can then be adopted and applied for regular screening and disease monitoring in SCD patients. To date, There has been a total of 19 subjects enrolled (13 SCD and 6 HbAA)