Significance: Untreated methemoglobinemia may cause severe hypoxemia and even death when methemoglobin levels in the blood stream exceed 70%. Although CO-oximetry can be used to monitor the response to treatment for methemoglobinemia, it is costly and requires an invasive procedure for collecting blood samples from patients. A pulse CO-oximeter with a contact probe can be used to continuously and non-invasively measure the percentage of methemoglobin, as well as the percutaneous oxygen saturation. In terms of the prevention of infectious diseases, however, it is desirable to monitor methemoglobin and oxygen saturation levels in a non-contact manner. Diffuse reflectance spectral imaging is promising as a non-contact, non-invasive, and cost-effective clinical diagnostic tool for methemoglobinemia. Aim: To demonstrate the feasibility of visible spectral diffuse reflectance for in vivo monitoring of hemoglobin derivatives and evaluating methemoglobin production and reduction as well as hypoxemia during methemoglobinemia in rats. Approach: A new imaging approach based on the multiple regression analysis aided by Monte Carlo simulations for light transport was developed to quantify methemoglobin, oxygenated hemoglobin, and deoxygenated hemoglobin using a hyperspectral imaging system. An in vivo experiment with rats exposed to sodium nitrite (NaNO2) at different doses was performed to confirm the feasibility of the method for evaluating the dynamics of methemoglobin, oxygenated hemoglobin, and deoxygenated hemoglobin during methemoglobinemia. Systemic physiological parameters, including the percutaneous arterial oxygen saturation, heart rate (HR), and pulse distention, were measured by a commercially available pulse oximeter, and the results were compared to those obtained by the proposed method. Results: Both the methemoglobin concentration and methemoglobin saturation rapidly increased with a half-maximum time of <20 min. They reached their maximal values nearly 60 min after the administration of NaNO2. Tissue oxygen saturation dramatically dropped to a minimum of 33.7 % ± 0.4 % , 23.1 % ± 5.6 % , 8.8 % ± 1.7 % , and 9.7 % ± 5.1 % on average for NaNO2 doses of 25, 37.5, 50, and 75 mg/kg, respectively. Changes in methemoglobin concentration and tissue oxygen saturation are indicative of the temporary production of methemoglobin and severe hypoxemia during methemoglobinemia. Profound increases in the HR and pulse distention implied an elevated cardiac output caused by tachycardia and the resultant increase in peripheral blood volume to compensate for the hypoxia and hypoxemia during methemoglobinemia. This was in agreement with the time course of the peripheral hemoglobin volume concentration obtained by the proposed method. Conclusions: The proposed method is capable of the in vivo non-contact simultaneous evaluation of methemoglobin levels and hypoxemia during methemoglobinemia, and that it has potential as a tool for the diagnosis and management of methemoglobinemia.

中文翻译：

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使用光谱漫反射对大鼠高铁血红蛋白血症期间血红蛋白衍生物的经皮监测

意义：当血流中的高铁血红蛋白水平超过 70% 时，未经治疗的高铁血红蛋白血症可能导致严重的低氧血症甚至死亡。虽然 CO 血氧饱和度测定法可用于监测对高铁血红蛋白血症治疗的反应，但它成本高昂，并且需要从患者身上采集血液样本的侵入性程序。带接触探头的脉搏血氧饱和度计可用于连续无创地测量高铁血红蛋白的百分比以及经皮氧饱和度。然而，就传染病的预防而言，希望以非接触方式监测高铁血红蛋白和氧饱和度水平。漫反射光谱成像有望成为高铁血红蛋白血症的非接触、非侵入性和经济高效的临床诊断工具。目的：证明可见光谱漫反射在体内监测血红蛋白衍生物和评估大鼠高铁血红蛋白血症期间高铁血红蛋白的产生和减少以及低氧血症的可行性。方法：开发了一种新的成像方法，该方法基于光传输的蒙特卡罗模拟辅助的多元回归分析，以使用高光谱成像系统量化高铁血红蛋白、氧合血红蛋白和脱氧血红蛋白。对暴露于不同剂量亚硝酸钠 (NaNO2) 的大鼠进行了体内实验，以确认该方法在高铁血红蛋白血症期间评估高铁血红蛋白、氧合血红蛋白和脱氧血红蛋白动力学的可行性。全身生理参数，包括经皮动脉血氧饱和度、心率 (HR)、通过市售脉搏血氧仪测量脉搏膨胀和脉搏膨胀，并将结果与​​通过所提出的方法获得的结果进行比较。结果：高铁血红蛋白浓度和高铁血红蛋白饱和度均迅速增加，半峰时间<20 分钟。它们在施用 NaNO2 后近 60 分钟达到最大值。对于 25、37.5、50 和 7 毫克的 NaNO2 剂量，组织氧饱和度显着下降到最小值 33.7 % ± 0.4 %、23.1 % ± 5.6 %、8.8 % ± 1.7 % 和 9.7 % ± 5.1 % ， 分别。高铁血红蛋白浓度和组织氧饱和度的变化表明高铁血红蛋白血症期间会暂时产生高铁血红蛋白和严重的低氧血症。HR 和脉搏膨胀的显着增加意味着由心动过速引起的心输出量升高，以及由此导致的外周血容量增加以补偿高铁血红蛋白血症期间的缺氧和低氧血症。这与通过所提出的方法获得的外周血红蛋白体积浓度的时间过程一致。结论：所提出的方法能够在体内非接触式同时评估高铁血红蛋白血症期间的高铁血红蛋白水平和低氧血症，并且它具有作为诊断和管理高铁血红蛋白血症的工具的潜力。