What Is a Finger Pulse Oximeter?

Pulse oximetry provides a non-invasive way to measure blood oxygen saturation or arterial hemoglobin saturation.

Pulse oximetry provides a non-invasive way to measure blood oxygen saturation or arterial hemoglobin saturation.

The pulse oximeter can also detect arterial pulses, so it can also calculate and inform the patient's heart rate.

Pulse oximeter is a medical device that measures the oxygen content in the arterial blood of a patient.

Chinese name

Pulse oximeter

Foreign name

pulse oximeter

For people

Heart disease, hypertension, diabetes

Major components

A microprocessor, memory

Measurement principle

Based on changes in light absorption during arterial pulsation

Basic functions of pulse oximeter

In addition to heart rate, blood pressure, breathing frequency, and temperature, pulse oximetry (PO) is considered the fifth most important indicator of health status. Hemoglobin (Hb) is an important part of blood cells and is responsible for transporting oxygen from the lungs to other tissues in the body. The amount of oxygen that hemoglobin contains at any one time is called oxygen saturation. Oxygen saturation is expressed as a percentage and it 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 our various tissues are healthy. Severe hypoxia can directly lead to tragedy 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 oxygen, and the oximeter has a high penetration rate.

Pulse Oximeter Measurement Principle

Based on changes in light absorption during arterial pulsation. Two light sources respectively located in the visible red light spectrum (660 nanometers) and the infrared spectrum (940 nanometers) alternately illuminate the test area (generally a fingertip or an 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 absorbed spectra and compares the result with a table of saturation values stored in memory to obtain the bleeding 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 based on measuring these two wavelengths of light with different absorption rates through the body.

Pulse oximeter for people

Patients must monitor blood oxygen during first aid and transfer, fire rescue, and high-altitude flight; heart disease, high blood pressure, and diabetes, especially the elderly will have breathing problems. Monitoring blood oxygen indicators can better understand their own breathing, Whether the immune system is normal, blood oxygen saturation has become an important physiological indicator for daily monitoring of ordinary families; medical personnel also use blood oxygen as a mandatory monitoring item during rounds and visits, and the amount used tends to overwhelm the stethoscope; patients with respiratory diseases are particularly Patients who have been snoring for a long time, using ventilator and oxygen generator, use oximeter in daily life to monitor the treatment effect; outdoor athletes, mountain enthusiasts and sports people use oximeter when exercising, know in time Your own physical condition and take necessary protective measures.

Pulse oximeter main components

A microprocessor, memory (EPROM and RAM), two digital-to-analog converters that control LEDs, a device that filters and amplifies the signal received by the photodiode, and an analog-to-digital converter that digitizes the received signal to the microprocessor . LEDs and photodiodes are placed in small probes that make contact with the patient's fingertips or earlobe. Pulse oximeters also typically include small liquid crystal displays.