Gardosi J O, Damianou D, Schram C M
Department of Obstetrics and Gynaecology, University of Nottingham, United Kingdom.
Am J Obstet Gynecol. 1994 Apr;170(4):1169-73. doi: 10.1016/s0002-9378(94)70116-4.
Our purpose was to investigate apposition of reflectance sensors as a possible source of artifact in fetal pulse oximetry.
A laboratory model was created to examine the effect of varying the distance of a reflectance probe from a subject's finger. The setup used two wavelengths (660 and 940 nm) and pulsatile (AC) and nonpulsatile signals (DC). An investigator's finger was stabilized in a purposely built mold from where the distance between skin and sensors could be varied in 1 mm steps.
The AC and DC components of the signal react differently to increasing the distance between sensor and skin. The overall effect is that the ratio [formula: see text] increases with skin to sensor distance, which results in falsely low readings of oxygen saturation.
Poor sensor-to-skin contact in reflectance pulse oximetry may cause false readings despite the presence of good waveforms and hence go unrecognized. Probe and software design needs to be able to identify and exclude such artifact before this technique can become useful for intrapartum fetal monitoring.
我们的目的是研究反射传感器的贴合情况，其作为胎儿脉搏血氧测定中伪像的一个可能来源。
创建一个实验室模型，以检查改变反射探头与受试者手指之间距离的影响。该装置使用两个波长（660和940纳米）以及脉动（交流）和非脉动信号（直流）。将一名研究者的手指固定在特制模具中，从该模具中皮肤与传感器之间的距离可以以1毫米的步长变化。
信号的交流和直流成分对增加传感器与皮肤之间的距离反应不同。总体效果是，[公式：见原文]这个比率随皮肤到传感器的距离增加，这导致氧饱和度读数错误地偏低。
尽管波形良好，但反射式脉搏血氧测定中传感器与皮肤接触不良可能导致错误读数，因此未被识别。在这项技术可用于产时胎儿监测之前，探头和软件设计需要能够识别并排除此类伪像。
