Home 5 News 5 5th Vital Sign: Blood Oxygen Saturation from Pulse Oximeter Test
5th Vital Sign: Blood Oxygen Saturation from Pulse Oximeter Test

Nov 17, 2022

How Pulse Oximeters Work

As the fifth vital sign, the pulse oximeter is routinely used by every hospital in the world. This important indicator is also one of the standards for monitoring the health of every patient, making the pulse oximeter the best in non-invasive respiratory monitoring. Optionally, the principle of the pulse oximeter is based on Beer’s law, and the technical level is calculated from the estimated values ​​of oxyhemoglobin (HgbO 2 ) and deoxyhemoglobin (Hgb) levels.

Pulse oximeters are based on the use of photodetectors to measure two wavelengths of light, transmitted from two light-emitting diodes (LEDs) through a pulsatile vascular bed (e.g., a finger) and impinging on a photodetector, a body part (bones, Tissues, pigmentation, and venous blood vessels) absorb a certain amount of light and the ratio of absorbed light increases over time in systole and diastole is defined as blood oxygen saturation, which is obtained by transmitting the measured readings to the OLED screen.


Clinical role of pulse oximeter

Examples of patient monitoring using pulse oximetry include respiratory testing, infants, pre-visit physician testing, and ICU. Pulse oximetry has become an important standard of care during anesthesia since its recommendation by the American Society of Anesthesiologists in 1986 recommends pulse oximetry as part of the monitoring of patients receiving sedatives and analgesics, according to studies.

As we all know, the first four vital signs are heart rate, respiratory rate, temperature, and blood pressure. For anesthesiologists, ICU doctors, and emergency doctors, oxygen saturation is the fifth vital sign. There are many opinions about the fifth vital sign, such as pain, but in most emergencies, the value of oxygen saturation is more important than pain. Regardless of any serious illness that is not caused by heart rate, blood pressure, respiratory rate, body temperature rise and fall, oxygen saturation drop, or pain, pay close attention to vital signs and keep the disease away from you.

Introduction to the 5 vital signs

1. Heart rate

Heart rate, also called pulse rate, is the number of times the heart beats per minute. Doctors typically use the pulse to detect abnormal rhythms, and medical professionals use a stethoscope to measure heart rate.
A typical resting heart rate for an adult is between 60 and 100 beats per minute (bpm). The main factors that affect your heart rate are age, your health, exercise, illness, mood, and medications.

2. Respiratory rate

The number of times you breathe per minute is called respiratory rate, which is usually measured when you are resting. Respiratory rate is an important indicator for detecting diseases. Normal exercise or nasal congestion can cause changes in breathing rate, but slow breathing or lack of oxygen could be the result of illness or other respiratory problems.

3. Temperature

Temperature is used as a signal to the doctor for fever, infection, and inflammation. Checking your body temperature at the same time every day can provide a standard line because the body temperature has different values ​​​​at different times. For example, the body temperature of breakfast is relatively low. The body temperature is relatively high at night, and it will be higher after exercise.

4. Blood pressure

Blood pressure includes systolic blood pressure and diastolic blood pressure. The systolic blood pressure measured after systole is generally higher, and the diastolic blood pressure measured before systole is generally lower. Doctors usually use a cuff to measure blood pressure. Blood pressure and heart rate are different vital signs.

Normal blood pressure for adults is generally less than 120 systolic and 80 diastolic. The main factors affecting blood pressure are drinking, smoking, anxiety, chronic diseases, family history, and drugs.

5. Pulse oximeter

Oxygen saturation is the unofficial fifth vital sign, and pulse oximeters measure blood oxygen levels in the blood, which is the amount of oxygen carried by red blood cells through the circulatory system. There are two methods to measure the blood oxygen level at the current level of technology, one is the arterial blood test, and the other is the pulse oximeter test, which is also a non-invasive test. The blood oxygen level of normal people is generally 95% to 100%. between.
Many factors affect the blood oxygen level, you can check this link for details:


Several advantages of pulse oximeter

Compared with an arterial blood test, a pulse oximeter has obvious advantages. It is non-invasive, painless, low in price, and can be tested anytime and anywhere. Faster results can be obtained and your doctor can give you advice and advice in a limited time. Many serious diseases cannot afford to wait to start treatment. The pulse oximeter is easy to operate, does not require training, and can be operated by the elderly and children. It is small in size and easy to carry.

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