Pulse Oximeter

Pulse Oximeter

Pulse oximeters provide a noninvasive method to measure blood oxygen saturation or arterial hemoglobin saturation.

Pulse oximeter can also detect arterial pulsation, so it can also calculate and inform the patient’s heart rate.

Pulse oximeter is a medical device for measuring the oxygen content in the arterial blood of patients

basic skills

In addition to heart rate, blood pressure, respiratory rate and temperature, pulse oximetry (PO) is considered to be the fifth most important health indicator. Hemoglobin (Hb) is an important component of blood cells. It is responsible for transporting oxygen from the lungs to other tissues in the body. The amount of oxygen contained in hemoglobin at any time is called oxygen saturation. Oxygen saturation is expressed as a percentage, which is the ratio of the oxygen content of hemoglobin to the oxygen carrying capacity of hemoglobin. Blood oxygen saturation is an important physiological parameter that reflects whether the human respiratory function and oxygen content are normal. It is an important physiological parameter that shows whether the various tissues of our body are healthy. Severe hypoxia will directly lead to tragedies such as suffocation, shock and death. In developed countries such as Europe and the United States, people attach great importance to the monitoring of blood oxygenation, and the oximeter has a very high penetration rate.

Measuring principle

Based on changes in light absorption during arterial pulse. Two light sources located in the visible red light spectrum (660 nanometers) and the infrared spectrum (940 nanometers) alternately illuminate the area under test (generally the fingertip or earlobe). The amount of light absorbed during these pulsations is related to the oxygen content in the blood. The microprocessor calculates the ratio of the two spectra absorbed, and compares the result with the saturation value table stored in the memory to obtain the hemorrhagic oxygen saturation.

A typical oximeter sensor has a pair of LEDs that face a photodiode through the translucent part of the patient’s body (usually the fingertip or earlobe). One of the LEDs is red and the wavelength is 660nm; the other is infrared and the wavelength is 940nm. The percentage of blood oxygen is calculated based on measuring the light of these two wavelengths with different absorption rates passing through the body.

For people

Patients must monitor blood oxygen during first aid and transport, fire rescue, and high-altitude flight; people with heart disease, high blood pressure, and diabetes, especially the elderly, have breathing problems. Monitoring blood oxygen indicators can help you understand your breathing, Whether the immune system is normal and blood oxygen saturation has become an important physiological index for daily monitoring of ordinary families; medical staff also take blood oxygen as a necessary monitoring item during ward rounds and visits, and the number of use has a tendency to exceed the stethoscope; patients with respiratory diseases are particularly Patients who are snoring for a long time, use ventilator and oxygen generator, use oximeter to monitor the treatment effect in daily life; outdoor athletes, climbing enthusiasts, sports athletes all use oximeter during exercise, know in time Own physical condition and take necessary protective measures.

Main components

A microprocessor, memory (EPROM and RAM), two digital-to-analog converters that control the LED, a device that filters and amplifies the signal received by the photodiode, and an analog-to-digital converter that digitizes the received signal to provide to the microprocessor . The LED and photodiode are placed in a small probe that comes in contact with the patient’s fingertip or earlobe. Pulse oximeters also generally include small liquid crystal displays.