ASOURCE Navi

As the infection of the new coronavirus spreads, a pulse oximeter (pictured above) that can measure blood oxygen saturation, which is a measure of the severity of the disease, is being highlighted.

When pneumonia develops and the lungs are damaged, oxygen is not sufficiently distributed from the lungs into the blood and oxygen saturation decreases. Measurement of blood oxygen concentration is used as a guide for determining the medical condition of new corona patients. Medical institutions use a device called a pulse oximeter to attach it to the patient's fingertips and measure the ratio of red blood cell hemoglobin bound to oxygen in the arterial blood. According to the "Guide for Medical Treatment of Coronavirus Infection (COVID-19)" formulated by the research group of the Ministry of Health, Labor and Welfare, "96% or more" of blood oxygen saturation in patients with new coronavirus infection is mild, "93". "More than% to less than 96%" is evaluated as moderate I (without respiratory failure), and "93% or less" is evaluated as moderate II (with respiratory failure). If the patient needs to enter the ICU or have a ventilator, it is considered severe.

In the past, it has become possible to easily obtain data that could not be measured without collecting blood from the arteries, and oxygen saturation is also called the "fifth biological sign after blood pressure, pulse, body temperature, and respiratory rate."

As a precaution for measurement, if the peripheral circulation is poor, such as when you move your hand or your finger is cold, it will not be measured correctly. Also, if light transmission is obstructed by manicure or nails, it cannot be measured accurately, so it must be removed before measurement. Be aware that smoking also affects the numbers.

Recently, some medical institutions have adopted monitoring of blood oxygen saturation for the examination of people with fever and other symptoms that are suspected to be corona infection.

Even if the new coronavirus infection is mild, pneumonia tends to progress rapidly and become severe without any noticeable subjective symptoms, and it has been reported that treatment is delayed and death occurs. Since these signs of aggravation appear in changes in the oxygen concentration in the blood, continuous measurement with a pulse oximeter can promptly lead to treatment when the condition worsens. Pulse oximeters have already been rented out to patients with coronavirus infection in hotel care, and in some municipalities, they are also rented out to home caregivers.

Another use for pulse oximeters is during surgery, where oxygen saturation is continuously monitored to ensure that the minimum life-supporting oxygen supply is not lost. It is also used as a simple test for sleep apnea syndrome (SAS), and by wearing it at home at bedtime and recording the oxygen saturation, it is possible to measure the time and frequency of decrease in oxygen concentration, pulse increase, etc. In recent years, it has been used not only in medical institutions but also in home visits and home-visit nursing.

Pulse oximeters are easy to operate and can be purchased at home, but it is not easy to determine what physical condition the measurements mean. The Japanese Respiratory Society advises, "Because it depends on the person's condition and the illness they are suffering from, it is recommended to seek the guidance of a medical specialist such as the attending physician when determining the measured values."