Finger pulse oximetry is the oxygen saturation level monitored at the fingertip, which reflects the oxygenation of the hemoglobin in the blood. A drop usually indicates hypoxia, which is usually above 98% in normal people, and even in sick people, it is usually not lower than 90%, and lower than 90% suggests that respiratory failure may occur. However, finger pulse oximetry is easily affected by a variety of factors, such as whether or not the clip is tight, whether or not it is aligned with the correct position of the finger, the thickness of the finger skin, the thickness of the fingernail, the color of the fingernail, the nail polish, and so on. Therefore, the significance of finger pulse oximetry should be viewed in perspective.