Basic skills
After heart rate, blood pressure, respiratory rate, and temperature, pulse oximetry (PO) are considered the 5th most critical health indicator. Hemoglobin (Hb) is an important component of blood cells responsible for transporting oxygen from the lungs to other tissues in the body. The amount of oxygen contained in hemoglobin at any one time is called oxygen saturation. Oxygen saturation, expressed as a percentage, is the ratio of the oxygen content of the hemoglobin to the oxygen-carrying capacity of the hemoglobin. Blood oxygen saturation is an important physiological parameter that reflects the respiratory function of the human body and whether the oxygen content is normal or not. Severe hypoxia will directly lead to suffocation, shock, death, and other tragedies. In developed countries such as Europe and the United States, people attach great importance to the monitoring of blood oxygen, and the oximeter has a high penetration rate.
Measurement principle
Based on changes in light absorption during arterial pulsations. Two light sources located in the visible red spectrum (660 nm) and the infrared spectrum (940 nm) alternately illuminate the test area (usually fingertips or earlobes). The amount of light absorbed during these pulsations is related to the oxygen content in the blood. The microprocessor calculates the ratio of these two spectra absorbed and compares the result with a table of saturation values stored in memory to obtain the oxygen saturation.
A typical oximeter sensor has a pair of LEDs that face a photodiode through a translucent part of the patient's body (usually a fingertip or earlobe). One of the LEDs is red with a wavelength of 660nm; the other is infrared with a wavelength of 940nm. The percentage of blood oxygen is calculated by measuring these two wavelengths of light with different absorption rates as they pass through the body.