Lower-limb strength is a marker of functional decline in elders. This work studies the feasibility of using the quasi-periodic nature of the distance between a subjects' back and the chair backrest during a 30-s chair-stand test (CST) to carry out unsupervised measurements based on readings from a low-cost ultrasound sensor. The device comprises an ultrasound sensor, an Arduino UNO board, and a Bluetooth module. Sit-to-stand transitions are identified by filtering the signal with a moving minimum filter and comparing the output to an adaptive threshold. An inter-rater reliability (IRR) study was carried out to validate the device ability to count the same number of valid transitions as the gold-standard manual count. A group of elders (age: mean (m) = 80.79 years old, SD = 5.38; gender: 21 female and seven male) were asked to perform a 30-s CST using the device while a trained nurse manually counted valid transitions. Ultimately, a moving minimum filter was necessary to cancel the effect of outliers, likely produced because older people tend to produce more motion artefacts and, thus, noisier signals. While the intra-class correlation coefficient (ICC) for this study was good (ICC = 0.86, 95% confidence interval (CI) = 0.73, 0.93), it is not yet clear whether the results are sufficient to support clinical decision-making.

中文翻译：

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基于便携式超声的设备，用于在无监督的30秒椅位测试中检测老年人的坐姿到站姿转换。

下肢力量是老年人功能下降的标志。这项工作研究了在30秒钟的座椅站立测试（CST）期间利用受试者的背部和椅子靠背之间的距离的准周期性质来进行基于低成本超声读数的无监督测量的可行性传感器。该设备包括超声传感器，Arduino UNO板和蓝牙模块。通过使用最小移动滤波器对信号进行滤波并将输出与自适应阈值进行比较，可以确定从站到站的过渡。进行了评估者间可靠性（IRR）研究，以验证该设备对与金标准手动计数相同数量的有效转换进行计数的能力。一组长者（年龄：平均（m）= 80.79岁，SD = 5.38；性别：要求21位女性和7位男性使用该设备执行30秒的CST，而受过训练的护士手动计算有效的过渡时间。最终，必须使用最小移动滤波器来消除离群值的影响，这可能是由于老年人倾向于产生更多的运动伪像，从而产生更嘈杂的信号而产生的。尽管本研究的组内相关系数（ICC）很好（ICC = 0.86，95％置信区间（CI）= 0.73，0.93），但尚不清楚结果是否足以支持临床决策。