What Is Normal Oxygen Level by Age? A Guide for Seniors

Oxygen levels in blood and heart rate are directly related to the well-being of any person. Those parameters can be impacted depending on age or even during sleep times. Thanks to pulse oximeter devices and the latest technology, we can now monitor those parameters remotely, 24/7, accurately, making them ideal for our beloved older adults. If you want an easy, quick, and complete guide about this, the science behind it, and its practical uses, this article has been written for you.

Oxygen in our body

The human body is made of cells (from head to toe). These cells need oxygen to make energy.

To deliver oxygen to all our body cells, we take the oxygen from the air, it enters our lungs, and then it is transferred (diffused) to our blood vessels (where the blood is flowing thanks to the heart pumping). Once in the blood vessels, the oxygen enters the red blood cells and is picked up by a very important molecule called hemoglobin, which will carry the oxygen and deliver it to all the cells in our body so that they can produce their energy to survive.

Because of this, oxygenation in our body is influenced by two important parameters:

  • Oxygen saturation level (how much oxygen is in our blood, carried by the hemoglobin molecule).
  • Heart rate (The number of times the heart beats per minute).

It is possible to measure those two parameters by using a device called a pulse oximeter.

What is a pulse oximeter and how does it work?

A pulse oximeter is a small portable device that can measure how much oxygen we have in our blood (oxygen saturation level), and the number of times the heart beats per minute (heart rate).

Measuring oxygen in our blood

Oximeter

The pulse oximeter detects whether the hemoglobin molecule is carrying oxygen (oxygenated) or not (deoxygenated) by utilizing two types of light. The first light (940 nm wavelength, Infrared light) will detect the oxygenated hemoglobin, and the second light (660 nm wavelength) will detect the deoxygenated hemoglobin.

How does it do that? This device comprises two essential components: tiny light-emitting diodes (LEDs) that emit the two types of light and a small sensor that can detect the light coming from the LEDs. Both components are located on opposite sides of the device.

Once the device sandwiches the finger, the light is triggered from the LED side, passes through the finger, and reaches the other side where the tiny sensor is located. Oxygen levels will be calculated based on how much light can reach the sensor and how much is absorbed by the hemoglobin molecule that travels in the blood vessels of our fingers.

How to use a pulse oximeter on older adults

Pulse oximeters are designed so anyone, from youth to older adults, can use them efficiently. Most have a user-friendly interface that facilitates the user experience. No matter the brand or the cost of the device, all of them work with the same universal principle:

  1. Turn on the pulse oximeter device.
  2. Warm your hands a little (check FAQs to know why).
  3. Clip the device onto your finger (preferably index or middle finger).
  4. Rest your hand on a comfortable flat surface for around one minute (the pulse oximeter will be working during that time).
  5. Done, the pulse oximeter will give you the results on the small display screen (oxygen saturation level and beats per minute "BPM").

Normal oxygen saturation and heart rate levels by age

The heart rate tells how many times the heart beats per minute (BPM), whereas oxygen saturation tells the oxygen percentage in the blood. These two values can vary between individuals based on age. Normal average oxygen saturation levels are from 95-100% for healthy people (from children to older adults). For people with chronic diseases, their normal levels may be lower. A healthcare provider can advise on what individualized oxygen saturation range is considered normal for a person. Hypoxia is low oxygen levels in tissue. Hypoxemia is low oxygen levels in the blood. It is advisable that individuals monitor their symptoms, but generally, if the reading is less than 92%, a person should contact their healthcare provider immediately.

The heart rate can also vary depending on an individual's physical activity. The target heart rate of someone doing moderate-intensity activity (50–85%) can be visualized in the chart below:

AgeTarget heart rate zone (50–85%)
20100–170 bpm
3095–162 bpm
4090–153 bpm
5085–145 bpm
6080–136 bpm
7078–128 bpm
8075–128 bpm

Comparison between different target heart rate zone (50–85%) with respect to different ages.

Oxygen levels and heart rate during sleep

During sleep, the body’s physical activity decreases considerably. However, the oxygen levels remain the same as during a normal day.

On the other side, heart rate indeed decreases during sleep. A normal resting heart rate is 60-100 bpm for a healthy individual, as seen below:

AgeTarget heart rate when awake
2068–96 bpm
3065–95 bpm
4063–94 bpm
5061–90 bpm
6060–87 bpm
7060–86 bpm
8063–85 bpm

Comparison between different target heart rates when a person is awake, according to age.

Alternatives to conventional fingertip pulse oximeter devices

Most older adults do not require continuous oxygen saturation (SPO2) monitoring. However, people with respiratory or cardiac conditions more so than mobility issues would require 24/7 monitoring. In such situations, monitoring oxygen levels 24/7 in real-time becomes beneficial. Nevertheless, conventional fingertip pulse oximeters can only provide one measurement at a time.

In those cases, alternative options exist, such as wrist pulse oximeters and flexible finger clip oximeters.

On the one hand, wrist pulse oximeters have the advantage of being compact and wearable. These devices can monitor oxygen levels, pulse rate, and even user motion and send them wirelessly to a smartphone. The smartphone app allows the measurements to be visualized, stored, and monitored in real-time. Wrist pulse oximeters can be used overnight and have embedded an alarm that activates if blood oxygen saturation levels fall below a defined level.

Conversely, flexible finger clip pulse oximeters are made to be used in-house or outdoors. They are made with conformable micro-foam material, which is not only a light material but also gives maximum comfort to the user. Moreover, they can provide extended oxygen level measurements, which is ideal for a prolonged amount of time. They are also disposable and latex-free, avoiding any allergy related to their use. However, user movements are limited since this device comes with a wire that must be connected to a portable device to record the oxygen signals throughout the day.

Note: Any device placed on the skin should be cleaned prior and after each use. For long periods of time, it should be checked every two hours for skin integrity.

Future technology of pulse oximeter devices for older adults

Recent research has been carried out, developing (École des Mines de Saint-Étienne, France, as an example) during the last years, developing implantable flexible pulse oximeters that can work 24/7 and provide real-time wireless monitoring. This could even enable integrating an emergency alert system within an implantable pulse oximeter in the near future, taking care of the person all the time, anywhere, anytime, and providing quick support if necessary.

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