Dassel A C, Graaff R, Sikkema M, Meijer A, Zijlstra W G, Aarnoudse J G
Department of Obstetrics and Gynecology, University Hospital Groningen, The Netherlands.
J Clin Monit. 1995 Jul;11(4):237-44. doi: 10.1007/BF01617518.
In this study, we investigated the possibility of improving reflectance (back-scatter) pulse oximetry measurements by pressure applied to the probe. Optimal signal detection, with the probe applied to an easily accessible location, is important to prevent erroneous oxygen saturation readouts. At the foreheads of 10 healthy adult volunteers, the effects of pressure applied onto the reflectance pulse oximeter probe were studied. Distances between the LEDs (660 nm and 940 nm) and the three photodiodes in the sensor were 4 mm, 7 mm, and 10 mm. For each detector, recordings were evaluated regarding red-to-infrared (R/IR) ratios and pulse sizes in relation to the stepwise increased pressure applied to the probe. R/IR variability decreased with applied pressures between 60 and 120 mm Hg. These findings are partly attributed to a corresponding increase in red and infrared pulse sizes at the detectors, which results in an improved signal-to-noise ratio. It is thought that pressure onto the oximeter sensor forces venous blood out of the tissues underneath the sensor. Consequently, the disturbing influence of pulsating and non-pulsating venous blood is reduced. Moreover, the increased difference in vessel diameter between diastole and systole and the corresponding difference in light absorption and an increase in flow velocities, causes an increase in pulse size with increasing pressure on the probe. Pressure applied to the probe may be useful in increasing the accuracy of reflectance pulse oximetry.
在本研究中，我们调查了通过对探头施加压力来改善反射式（背散射）脉搏血氧饱和度测量的可能性。将探头应用于易于触及的位置以实现最佳信号检测，对于防止错误的血氧饱和度读数非常重要。在10名健康成年志愿者的前额，研究了施加在反射式脉搏血氧仪探头上的压力的影响。发光二极管（660纳米和940纳米）与传感器中的三个光电二极管之间的距离分别为4毫米、7毫米和10毫米。对于每个探测器，记录评估了与逐步增加施加在探头上的压力相关的红/红外（R/IR）比率和脉冲大小。在60至120毫米汞柱的施加压力下，R/IR变异性降低。这些发现部分归因于探测器处红、红外脉冲大小相应增加，从而导致信噪比提高。据认为，施加在血氧仪传感器上的压力会迫使静脉血流出传感器下方的组织。因此，脉动和非脉动静脉血的干扰影响得以降低。此外，舒张期和收缩期血管直径差异的增加以及相应的光吸收差异和流速增加，导致随着探头上压力增加脉冲大小增大。施加在探头上的压力可能有助于提高反射式脉搏血氧饱和度测量的准确性。
