Understanding Pulse Oximeters: A Full Beginner Guide

Knowing your oxygen levels could be a matter of life or death.

Whether you’re managing a chronic condition or simply monitoring your health at home, a pulse oximeter is an essential tool for tracking your body’s oxygen saturation.

But have you ever wondered how accurate these devices really are? Or what happens when a pulse oximeter registers an artificially low oxygen saturation?

In this guide, we’ll dive deep into how pulse oximeters work, their importance, and how to use them correctly for reliable results.

Ready to discover the ins and outs of pulse oximetry? Let’s get started!

How Pulse Oximeters Work?

A pulse oximeter measures how much oxygen your red blood cells are carrying – a value known as oxygen saturation (SpO₂). It does this by shining light through your fingertip (or earlobe) and analyzing how much light is absorbed by oxygenated versus deoxygenated blood.

Source

This method is called pulse oximetry, and it relies on a principle called spectrophotometry.

Oxygen-rich blood absorbs infrared light, while oxygen-poor blood absorbs more red light. The sensor uses this difference to calculate your pulse total oxygen supply in real time.

Though convenient and non-invasive, it’s important to remember that pulse oximeters measure oxygen saturation — not blood pressure, and they cannot directly detect conditions like a heart attack or AFib (atrial fibrillation). However, unusual readings might signal the need for further medical evaluation.

Understanding this basic function helps you use the device more confidently — whether you’re checking on a loved one or monitoring yourself during illness or exercise.

What Does Pulse Oximeter Measure?

Primarily, the device is used to measure the following key parameters:

Oxygen saturation levels (SpO₂): This is the percentage of hemoglobin saturated with oxygen with respect to the total hemoglobin in your blood. It indicates how well your red blood cells can carry oxygen.
Pulse rate: It is the rate at which your heart beats per minute.

What is Not Measured by a Pulse oximeter?

The two most commonly asked questions about the use of pulse oximeters are: Does a pulse oximeter measure blood pressure and can a pulse oximeter detect a heart attack?

It is essential to understand that pulse oximeters cannot be used for either purpose because they are not designed to record arterial pressure or monitor the electrical activity of the heart.

When to Use

A pulse oximeter is generally used to check oxygen levels as a part of routine health examination but healthcare providers may also use it to monitor blood oxygen saturation and pulse rate in the following situations:

To monitor the oxygen levels during and after surgeries, especially when anesthesia is administered.
To examine lung function in patients with reduced oxygen supply as a result of chronic respiratory diseases or health problems such as anemia and heart attack.
To assess individuals with sleep disorders.

Step by Step Guide on How to Correctly Use Pulse Oximeter

Pulse oximeters can be used in outpatient settings but it’s necessary to understand and carefully follow the steps outlined below to get the most accurate reading.

Step 1: Prepare Your Finger

Ensure your finger is bare by removing jewelry, nail paints, artificial nails, or other objects. A pulse oximeter can register an artificially low oxygen saturation if there is an interference with the light transmission of the device.
Disinfect your finger with an alcohol swab.
Make sure your hands are warm and relaxed by keeping them in a resting position for at least 5 minutes.
For an improved blood flow to your finger, place your hand on your chest slightly lower than your heart level.

Step 2: Attach the Device to Your Finger

Power on the pulse oximeter.
Place your finger inside the pulse oximeter with your nail facing upwards and attach the device.
Ensure that the probe of the device fits the finger. It should not be too tight to restrict blood circulation nor too loose.

Step 3: Wait for the Reading to Be Steady

Sit still and avoid any movement.
Wait for the numbers to stabilize till you get the highest fixed value. This may take several seconds or a minute.

Step 4: Record the Result

The screen will display the readings of pulse rate and oxygen saturation level.
Record the readings with the exact date and time at which the readings were taken.
Clean the surface of the probe as described in the device user manual.

Understanding Readings

Two readings will be displayed on the screen of Pulse oximeter:

%SpO2: Value of oxygen saturation (SpO₂) in percentage
PR bpm: Value of pulse rate in bpm

Oxygen Saturation (SpO₂)

Wondering what is normal oxygen level for elderly or what should a 2-year-olds oxygen level be?

Unlike other health parameters such as blood pressure and sugar levels that vary by age, oxygen saturation levels generally remain consistent in healthy individuals with subtle variations regardless of the age group.

Age	Oxygen saturation (SpO₂)
1 month – 2 years	95% or above for all ages.
2-10 years
10 years – adult (including seniors)

Generally, the oxygen level in healthy individuals of any age should be more than 95% but if your oxygen saturation level falls between 93% and 95%, it might need to be monitored by your GP.

SpO₂ of less than 93% is considered low and requires medical attention. The individual can be diagnosed with hypoxemia.

Pulse Rate (bpm)

Age	Pulse rate (bpm) at rest
1 month – 2 years	100 – 180
2-10 years	60 – 140
10 years – adult (including seniors)	50 – 100

When May Pulse Oximetry Be Inaccurate

Similar to any digital device, A pulse oximeter may register a false result in any of the following cases:

A colder temperature may cause the device to give inaccurate results. A colder temperature can cause vasoconstriction leading to the device’s inability to detect a pulse.

Bright lights from the surroundings may cause the Pulse oximeter to produce inaccurate readings.

Pigmentation on the finger such as from a tattoo or nail paints can interfere with the light emitted from the probe of the device.

FAQs on Oxygen Levels and Health

What should you do when the pulse oximeter alarms?

When your oxygen level drops dangerously below the safe limit it will trigger the device’s alarm.

Immediately look for any signs or symptoms that may indicate hypoxemia. These include shortness of breath, bluish lips or skin, mental disorientation, chest tightness, and racing pulse.

Ensure the probe is positioned correctly. Improper placement could trigger false alarms.

In case a low SpO2 level is confirmed, provide supplemental oxygen immediately or call for medical assistance.

Can low oxygen levels cause dizziness?

Yes, low oxygen levels result in the brain to receive insufficient oxygen leading to the symptoms of fatigue, confusion, and dizziness. Take proper actions if any of these symptoms are observed.

Can oxygen levels fluctuate?

Minor fluctuations in oxygen levels are considered normal and might be influenced by:

Physical factors: strenuous physical activities, sleeping.
Environmental factors: higher altitude leading to lower oxygen saturation.

Significant and persistent drop in oxygen level is not normal and can indicate an underlying health problem.

What is normal oxygen saturation during exercise?

The normal oxygen saturation for healthy individuals during exercise remains similar to the oxygen levels at rest (95% to 100%). A slight increase may be probable due to enhanced lung and heart activity but a significant drop in oxygen saturation is considered unusual.

What should a child’s oxygen level be?

Oxygen saturation reading above 95% is considered normal for healthy individuals of all ages.

What are the best pulse oximeters?

Before purchasing a pulse oximeter, it is necessary to determine the intended use of the device.

Pulse oximeters are available for use in hospital settings and are also sold as general wellness products.

Pulse oximeters intended for clinical purposes or those used by healthcare professionals provide medical-grade accuracy and are FDA-approved.

Some devices sold under the umbrella of general wellness products are not reviewed by a regulatory agency and are used for general wellness assessment, providing an estimated value.

Who invented the pulse oximeter?

Pulse oximeter was invented by a Japanese bioengineer, Takuo Aoyagi in 1974. His invention made a noninvasive method of measuring blood oxygen levels possible.

Can low battery affect pulse oximeter?

A low battery can be one of the reasons for pulse oximeters to provide unreliable readings or cause the device to malfunction altogether. Before taking a reading ensure that your pulse oximeter is fully charged and replace the batteries when needed.

How does pulse dose oxygen work?

Pulse dose oxygen, a method used in portable oxygen concentrators (POCs), delivers supplemental oxygen to patients in a customized manner tailored to their breath rate.

The sensor detects inhalation at the start of each breath and releases oxygen in small bursts which extends the battery life, and less oxygen is wasted, in contrast to a continuous flow system.

Final Words

Now you know all the basics of pulse oximeters! We’re soon going to share more about the best pulse oximeters to buy for home use – stay tuned!

If you have any specific questions about pulse oximeters, feel free to drop your query in the comments, we’ll get back to you asap.