Photoplethysmogram at green light: Where does chaos arise from?
Photoplethysmogram at green light: Where does chaos arise from?
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绿灯下的光电体积描记图：混乱从何而来？
DOI：
10.1016/j.chaos.2018.09.016
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Nakano Akimasa
中科院分区：
文献类型：
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作者：
Sviridova Nina;Zhao Tiejun;Aihara Kazuyuki;Nakamura Kazuyuki;Nakano Akimasa
在过去的几十年里，光体积描记术一直被常规地用于健康监测。尽管在日常医疗实践中，光体积图(PPG)是在红光和近红外光(RPPG)下记录的，但在过去的十年中，在绿灯下获得的PPG(GPPG)已被广泛应用于可穿戴设备，如腕带和智能手表，从而提供高度可用和可访问的日常健康监测。众所周知，在近红外光下获得的PPG信号包含了关于一个人健康的足够信息；此外，它们经过了充分的研究，并且非常复杂。相比之下，绿光PPG尚未得到充分研究；因此，尚不清楚所提供的信息是否与RPPG获得的信息一样有价值，因为绿光体积图是在乳头状真皮和较高皮肤水平形成的。然而，与rPPG相比，gPPG信号被认为对运动伪影具有更强的鲁棒性。鉴于rPPG动力学已被认为是混沌的，本研究旨在研究gPPG的性质，并将其与rPPG的性质进行比较，以确定gPPG动力学是否也是混沌的。这个问题的动机不仅是为了研究gPPG是否可以用于与rPPG相同的应用范围，而且也是为了深入了解rPPG的复杂性是仅仅由于组织更深层的过程，还是受到产生gPPG的较高层过程的影响。结果表明，gPPG和rPPG都是混沌的，这意味着上层的过程造成了PPG数据的混沌，而动脉血容量的变化对PPG数据的贡献并不完全清楚。
Photoplethysmography has been routinely used for health monitoring in the past decades. Even though in daily medical practice, photoplethysmograms (PPGs) are recorded at red and near infra-red light (rPPGs), during the last decade, PPGs obtained at green light (gPPGs) have been widely used in wearable devices, such as wristbands and smartwatches, thus providing highly usable and accessible daily health monitoring. It is well recognized that PPG signals obtained at NIR light contain sufficient information about a person's health; furthermore, they are well-studied and highly complex. By contrast, green light PPGs have not been sufficiently studied; thus, it is not clear whether the provided information is as valuable as that obtained by rPPGs, as green light photoplethysmography is formed at papillary dermis and higher skin levels. However, the gPPG signal is recognized to be more robust to motion artifacts compared with rPPGs. As rPPG dynamics has been recognized as chaotic, this study is aimed at investigating the properties of gPPGs and compare them with those of rPPGs to determine whether gPPG dynamics is chaotic as well. The motivation for this question was not only to investigate whether gPPGs can be used for the same range of applications as rPPGs but also to obtain insight into whether the complexity of rPPGs is solely due to processes in deeper layers of the tissue or it is influenced by the higher-skin layers processes that create gPPGs. The obtained results demonstrated that gPPGs, as well as rPPGs, are chaotic, which implies that processes in the upper layers create chaos in PPG data, whereas the contribution of arterial blood volume changes is not completely clear.