Is SpO2 Same As Blood Pressure

SpO2 and blood pressure are two distinct medical measurements usually used to determine a person’s health situation. Both remain closely related to the heart, the most critical organ of your body. But is SpO2 the same as blood pressure? Read on to know more about SpO2 and blood pressure.

What Is SpO2?

SpO2 (peripheral capillary oxygen saturation) estimates how much oxygen is in the blood. SpO2 is the percentage of oxygenated hemoglobin (against the whole amount of blood.

SpO2 is the estimate of arterial oxygen saturation (SaO2,) the quantity of oxygenated hemoglobin in the blood. Hemoglobin is the protein that carries oxygen in your blood. It’s found in red blood cells and is responsible for their red color.

Good blood oxygenation is essential to deliver the energy the muscles require to function, which increases when doing exercises. If your SpO2 value goes below 90 percent, it might be a warning of poor blood oxygenation (hypoxia).

What Is Blood Pressure?

Blood pressure is the force the blood uses to move through the arteries. When the heart pumps, it employs force that pushes blood-rich oxygen out to your arteries.

High blood pressure (hypertension) is when blood pressure becomes more elevated than usual. The blood pressure changes throughout the day depending on your activities. If your blood pressure is constantly above normal, it might result in high blood pressure (hypertension).

Higher blood pressure means more risk for additional health issues, like heart attack, heart disease, and stroke.

Is SpO2 Related to Blood Pressure?

Yes. When SpO2 decreases, increased blood pressure) increases  in people with oxygen desaturation, especially at high altitudes. Also, mean nocturnal SpO2 decreases in people with mild hypertension or high-normal BP than in those having normal BP.

Researchers did the study on nocturnal SpO2, morning and BP evening BP during daily life to examine the relationship between changes in blood pressure and nocturnal SpO2 (morning BP minus evening BP) to find out the SpO2 influence on BP.

The morning blood pressure increase from evening blood pressure was notably more significant in people with a low nocturnal SpO2. The SpO2 decrease during sleep might affect morning blood pressure rise.

Blood Pressure vs Arterial Blood Pressure

Arterial blood pressure is the force the blood uses on the main wall. It isn’t a cardiac output, and it shouldn’t be presumed that sufficient blood pressure is the same as enough cardiac output. Arterial blood pressure varies with every heartbeat, following the heart’s pumping.

To measure systolic blood pressure, direct or indirect methods can be used. With direct measurement, a catheter is positioned in a peripheral artery (typically dorsal femoral or pedal), a pressure transducer, and a monitor.

Indirect measurement is most practicable, but the most vital part to remember is that values obtained with indirect methods need to be more essentially accurate.

Measurement of SpO2 and Blood Pressure

The difference between SpO2 and blood pressure measurement is the components measured: the amount of oxygen in the blood versus the pressure against arteries. The doctor uses a sphygmomanometer and a stethoscope to take blood pressure measurements.

Blood pressure measurement is calculated in millimeters of mercury (mmHg). It uses two numbers:

  1. Systolic blood pressure: Measures the pressure in the arteries when the heart beats.
  2. Diastolic blood pressure: measures the pressure in the arteries when the heart breaks between beats. The systolic number is recorded first, and then the diastolic number.

Your health care provider can measure SpO2 in different ways. SpO2 can be measured using pulse oximetry. This is an indirect and non-invasive method which means that it doesn’t involve any instruments in the body. It is a proficient way to use a pulse oximeter. They are very accurate at detecting oxygen levels in your blood.

How to Measure SpO2 Using Pulse Oximetry

To measure SpO2 with a pulse oximeter, you just place it on a finger and wait for the screen to show a SpO2 percentage amount and blood pressure.

Pulse oximetry releases and absorbs a light wave that passes through blood capillaries or vessels in the fingertip. A disparity of the light wave passing through your finger gives the value of the SpO2 measurement since the amount of oxygen saturation causes contrast in the color of the blood.

Each SpO2 value is presented in percentages. When the Withings Pulse is 98 percent, each red blood cell is made of 98 percent oxygenated and 2 percent non-oxygenated hemoglobin. The normal SpO2 values differ between 90 percent and 100 percent.

Besides, assessing blood pressure can be done by fingertip pulse oximeters, a device not commonly used for that function.

This means assessing blood pressure can now take a turn in offering medical assistance.

The pulse oximeter that clips onto your finger or toe to measure oxygen levels in the blood and heart rate can detect normal or high blood pressure with a high percentage accuracy.

What Should Your Oxygen Levels And Blood Pressure Be?

An average blood pressure level should be less than 120/80 mmHg, 120-129 systolic, and 80-84 diastolic. Prehypertension stage 1 hypertension is between 121/80 mmHg to 139/89 mmHg, while hypertension or high blood pressure is 140/90 mmHg and above.

Severely low blood pressure means a significant danger in your body for not receiving sufficient oxygen to do its normal functions. A fall from 110 mm Hg systolic to, for example, 90 mm Hg systolic can make you feel dizzy and faint. Significant drops, like those caused by acute infections, uncontrolled bleeding, or allergic reactions, might be life-threatening.

Normal oxygen saturation levels should range between 95 -100 percent. Decreased oxygen levels can result in brain and heart damage. Furthermore, it signifies that your circulatory system might not function as it should.

If your SpO2 reading drops lower than 95 percent, consult your healthcare provider. However, people with chronic sleep apnea or lung disease might have a bit lower oxygen saturation levels, which is all right.

The Importance of Monitoring SpO2 and Blood Pressure

Monitoring the SpO2 and assessing blood pressure remain easy and convenient way of assessing the heart’s activity. Many diseases can affect blood pressure. Having abnormal blood pressure readings can be a sign of looming medical problems.

When assessing blood pressure and the results show severely below normal levels, there’s a noteworthy danger of your body not receiving sufficient oxygen to do its normal work. A drop-off in oxygen may result in weakened brain and heart functioning and cause breathing problems.

Heart failure makes the heart become a weaker pump. After a while, it reduces its effectiveness of pumping oxygen-rich blood throughout your body. This might result in dropping in your oxygen levels (hypoxemia.)

Hypoxemia occurs when oxygen in your blood is below normal levels, especially in the arteries. It is a sign of a problem associated with breathing or circulation and might result in a variety of symptoms, like shortness of breath.

Oxygen saturation is a vital element that maintains the health of every tissue in your body. Oxygen is firmly regulated inside the body since hypoxemia might cause severe harmful effects on your organ systems, such as the heart, brain, and kidneys.


Use of Pulse Oximeter for Blood Pressure Measurement

A pulse oximeter is a monitoring device commonly used in the medical field to measure and analyze oxygen saturation levels in the blood. The doctor can also use the machine in assessing blood pressure.

The pulse oximeter is put on the patient’s fingertip to detect oxygen saturation levels in the blood to guarantee adequate oxygen reaches the brain. Your healthcare provider can use this tool on a finger or toe in two ways.  

The first way is using a band-aid-like glue strip gripping the light source as well as the detector. The other way is by a two-tonged plastic tool that folds around the finger with a monitor to read or a cable to cork into a computer.

The pulse oximeter’s biolight sensor can calculate the heart rate of the patient and oxygen levels in the blood and detect normal, elevated, and high blood pressure with 95 percent accuracy. An exact percentage of oxygen saturation, beat-to-beat, and the current heart rate flash out as a digital readout.

The simple and smooth function of the machine and its ability to provide a crucial report about the patient’s condition gave its full approval in the medical field.

So pulse oximeters are the innovations that help concisely detect hypoxia. Pulse oximeters are most regularly used with sedated patients to monitor oxygen status constantly, accurately, and non-invasively.

Pulse oximeters are excellent in measuring systolic arterial blood pressure. It is essential for those with pulseless diseases like Takayasu’s syndrome, where normal methods regularly fail to detect systolic arterial blood pressure.

Pulse oximeters are the most major progress in patient monitoring. They show the satisfactory function of the circulatory and respiratory systems.


Bottom Line

Measuring SpO2 and assessing blood pressure are different but closely related in terms of monitoring heart health. In 2020, over 670,000 deaths in the US had hypertension as a contributing or main cause. Regular checkups and protective measures remain the most excellent early detection and prevention methods.