Barker S J, Shah N K
Department of Anesthesiology, University of Arizona, Tucson, USA.
Anesthesiology. 1997 Jan;86(1):101-8. doi: 10.1097/00000542-199701000-00014.
Pulse oximetry is considered a standard of care in both the operating room and the postanesthetic care unit, and it is widely used in all critical care settings. Pulse oximeters may fail to provide valid SpO2 data in various situations that produce low signal-to-noise ratio. Motion artifact is a common cause of oximeter failure and loss of accuracy. This study compares the accuracy and data dropout rates of three current pulse oximeters during standardized motion in healthy volunteers.
Ten healthy volunteers were monitored by three different pulse oximeters: Nellcor N-200, Nellcor N-3000, and Masimo SET (prototype). Sensors were placed on digits 2, 3, and 4 of the test hand, which was strapped to a mechanical motion table. The opposite hand was used as a stationary control and was monitored with the same pulse oximeters and an arterial cannula. Arterial oxygen saturation was varied from 100% to 75% by changing the inspired oxygen concentration. While SpO2 was both constant and changing, the oximeter sensors were connected before and during motion. Oximeter errors and dropout rates were digitally recorded continuously during each experiment.
If the oximeter was functioning before motion began, the following are the percentages of time when the instrument displayed an SpO2 value within 7% of control: N-200 = 76%, N-3000 = 87%, and Masimo = 99%. When the oximeter sensor was connected after the beginning of motion, the values were N-200 = 68%, N-3000 = 47%, and Masimo = 97%. If the alarm threshold was chosen SpO2 less than 90%, then the positive predictive values (true alarms/total alarms) are N-200 = 73%, N-3000 = 81%, and Masimo = 100%. In general, N-200 had the greatest SpO2 errors and N-3000 had the highest dropout rates.
The mechanical motions used in this study significantly affected oximeter function, particularly when the sensors were connected during motion, which requires signal acquisition during motion. The error and dropout rate performance of the Masimo was superior to that of the other two instruments during all test conditions. Masimo uses a new paradigm for oximeter signal processing, which appears to represent a significant advance in low signal-to-noise performance.
脉搏血氧饱和度测定法在手术室和麻醉后护理单元均被视为一种护理标准，并且在所有重症监护环境中广泛应用。在各种导致低信噪比的情况下，脉搏血氧仪可能无法提供有效的SpO2数据。运动伪影是血氧仪故障和准确性丧失的常见原因。本研究比较了三种当前脉搏血氧仪在健康志愿者进行标准化运动期间的准确性和数据丢失率。
十名健康志愿者由三种不同的脉搏血氧仪进行监测：Nellcor N - 200、Nellcor N - 3000和Masimo SET（原型）。传感器放置在测试手的示指、中指和环指上，该手被绑在机械运动台上。对侧手用作静止对照，并用相同的脉搏血氧仪和动脉插管进行监测。通过改变吸入氧浓度使动脉血氧饱和度从100%变化至75%。当SpO2保持恒定和变化时，在运动前和运动期间连接血氧仪传感器。在每个实验期间连续数字记录血氧仪误差和丢失率。
如果血氧仪在运动开始前正常工作，以下是仪器显示的SpO2值在对照值的7%范围内的时间百分比：N - 200 = 76%，N - 3000 = 87%，Masimo = 99%。当在运动开始后连接血氧仪传感器时，相应的值为N - 200 = 68%，N - 3000 = 47%，Masimo = 97%。如果将报警阈值设定为SpO2小于90%，那么阳性预测值（真警报数/总警报数）为N - 200 = 73%，N - 3000 = 81%，Masimo = 100%。总体而言，N - 200的SpO2误差最大，N - 3000的数据丢失率最高。
本研究中使用的机械运动显著影响血氧仪功能，特别是当在运动期间连接传感器时，这需要在运动期间采集信号。在所有测试条件下，Masimo的误差和丢失率表现均优于其他两种仪器。Masimo采用了一种新的血氧仪信号处理模式，这似乎代表了在低信噪比性能方面的重大进步。
