整个一段都没整明白

How does nonpulsatile skin pigmentation affect the pulse oximeter accuracy , particularly in producing a positive bias that might cause hypoxemia to be missed? The pulse oximeter measures the ratio of the pulse’s added absorbance in red and infrared light transmitted through the tissue. The ratio (R) is then empirically calibrated with human volunteer data to produce an “R calibration curve, ” (e.g., R = 3.4, Spo2 = 100%; R = 1.0, Spo2 = 85%). If the pigment acts as a variable light filter for the transmitted light frequency , the peak frequency could slightly change and produce a slightly changed R and slightly altered Spo2 value. The red light-emitting diodes used in pulse oximeters do not produce a single wavelength of red light, but rather a bell curve distribution of wavelengths, and the shorter wavelengths of this distribution are more heavily absorbed by melanin than the longer. In effect, the R curve for patients with darker skin pigmentation needs to be different than that for White patients.

非搏动性肤色如何影响脉氧仪的准确性，尤其正偏倚是否会漏诊低氧血症?脉氧仪测量脉搏在红光和红外光中透过组织的附加吸光度的比值。然后用志愿者数据对比值（R）进行经验校准，产生一个‘R校准曲线’（R=3.4 , Spo2=100%; R=1.0, Spo2=85%）。如果肤色对透射光频率起可变光滤波器的作用，峰值频率可能稍微改变，产生略改变的R值和Spo2值。脉氧仪中的红光发射二极管不产生单一波长的红光，这些红光的波长而是呈钟形曲线分布，且当波长越短，被黑肤色吸收就越多。实际上，深肤色患者，其R曲线与白人患者不同。

整个一段都没整明白？对吗