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What is SpO2?

Recently, pulse oximetry (SpO2) has received increasing attention from the public because some doctors recommend that patients diagnosed with COVID-19 monitor their SpO2 levels at home. Therefore, it makes sense for many people to wonder “What SpO2?” for the first time. Don’t worry, please read on and we will guide you through what SpO2 is and how to measure it.


SpO2 stands for blood oxygen saturation.Healthy adults usually have 95%-99% blood saturation, and any reading below 89% is usually cause for concern.

A pulse oximeter uses a device called a pulse oximeter to measure the amount of oxygen in red blood cells. The device will display your SpO2 as a percentage. People with lung diseases such as chronic obstructive pulmonary disease (COPD), asthma or pneumonia, or people who temporarily stop breathing during sleep (sleep apnea) may have lower SpO2 levels. Pulse oximetry can provide early warning capabilities for many lung-related problems, which is why some clinicians recommend that their COVID-19 patients regularly monitor their SpO2. More generally, clinicians often measure SpO2 in patients during simple examinations, because this is a quick and easy way to flag potential health problems or rule out other diseases.

Although it has been known since the 1860s that hemoglobin is the component of blood that transports oxygen to the whole body, it will take 70 years for this knowledge to be directly applied to the human body. In 1939, Karl Matthes developed a pioneer of modern pulse oximeters. He invented a device that uses red and infrared light to continuously measure oxygen saturation in the human ear. During World War II, Glenn Millikan developed the first practical application of this technology. In order to solve the problem of the pilot’s power outage during high-altitude maneuvers, he connected an ear oximeter (a term he coined) to a system that directly supplies oxygen to the pilot’s mask when the oxygen reading drops too low .

Nihon Kohden’s bioengineer Takuo Aoyagi invented the first real pulse oximeter in 1972, when he was trying to use an ear oximeter to track the dilution of the dye to measure the output of the heart rate. When trying to find a way to combat the signal artifacts caused by the subject’s pulse, he realized that the noise caused by the pulse was entirely caused by changes in arterial blood flow. After several years of work, he was able to develop a two-wavelength device that uses changes in arterial blood flow to more accurately measure the oxygen absorption rate in the blood. Susumu Nakajima used this technology to develop the first available clinical version, and began testing on patients in 1975. It was not until the early 1980s that Biox released the first commercially successful pulse oximeter for the respiratory care market. By 1982, Biox received reports that their equipment had been used to measure the blood oxygen saturation of anesthetized patients during surgery. The company quickly started work and began to develop products specifically designed for anesthesiologists. The practicality of measuring SpO2 during surgery was quickly recognized. In 1986, the American Society of Anesthesiologists adopted intraoperative pulse oximetry as part of its standard of care. With this development, pulse oximeters have been widely used in other hospital departments, especially after the release of the first self-sufficient fingertip pulse oximeter in 1995.

Generally speaking, medical professionals can use three types of equipment to measure the SpO2 of a patient: multi-function or multi-parameter, patient monitor, bedside or hand-held pulse oximeter or fingertip pulse oximeter. The first two types of monitors can continuously measure patients, and can usually display or print a graph of changes in oxygen saturation over time. Spot-check oximeters are mainly used for snapshot recording of the patient’s saturation at a specific time, so these are mainly used for examinations in clinics or doctors’ offices.

Post time: Apr-02-2021