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What Are the Different Types of Pulse Oximeter?

Pulse oximeters are devices designed to measure the oxygen saturation level and pulse rate in our blood. There are different types of pulse oximeters developed for specific needs. These devices can be used in different body parts such as the finger, toe, or earlobe. Although pulse oximeters can be used by anyone, they also play an important role in seniors and people with chronic diseases (such as respiratory or heart diseases), where sudden drops in blood oxygen levels may occur. Having the appropriate type of pulse oximeter nearby enables immediate detection of such fluctuations, facilitating prompt action when necessary.

How does a pulse oximeter work?

The principle of operation of a pulse oximeter is rather simple. Oxygen is carried in our blood vessels by a molecule called hemoglobin. Therefore, the goal is to detect if the hemoglobin molecules are carrying oxygen (oxygenated) or not (deoxygenated). How can we do that? By utilizing two different types of light. Infrared light (940 nm wavelength) can detect oxygenated hemoglobin; red light (660 nm wavelength) can detect deoxygenated hemoglobin.

A pulse oximeter consists of two important parts: a component that emits two types of light, called light-emitting diodes (LEDs), and a tiny sensor that can detect the light coming from the LEDs.

  1. The device is placed on a body part (e.g., finger).
  2. The two lights (wavelengths) are shined from the LEDs (pass through the blood vessels within the finger, reaching the other side where the tiny sensor is located).
  3. The sensor receives the light and calculates the oxygen levels based on how much light reaches the sensor, and how much light is absorbed by the oxygenated and deoxygenated hemoglobin molecules from the blood vessels.

Common configurations of pulse oximeters

Using this principle, there are two main configurations of pulse oximeter devices on the market:

pulse oximeter configurations
  • Transmission mode. LEDs and the sensor are located on opposite sides of the device, and the body part is sandwiched by the device. The light passes through the body part from one side to the other.
  • Reflective mode. LEDs and the sensor are next to each other in parallel. The light reaches the body part and is then reflected, like a mirror, to the other parallel side where the sensor is located.

Different types of pulse oximeters

Although the detection mechanism of most pulse oximeters relies on the same principle, there are different types based on specific needs:

Fingertip pulse oximeter

Fingertip pulse oximeter

This is the most common device that is clipped onto the finger. Its simplicity makes it one of the cheapest options available. However, it can only provide one single measurement each time (non-continuous).

Handheld pulse oximeter

Handheld pulse oximeter

Like the fingertip device, this pulse oximeter is finger-clipped. However, this one can be connected to a handheld monitor, which provides continuous oxygen level monitoring anywhere. Some of this pulse oximeters have a battery that lasts 18 hours and 500 hours of data storage. Commonly used for adults, pediatrics, and neonates.

Wrist pulse oximeter

Wrist pulse oximeter

Wrist devices offer the same features while incorporating a compact monitor seamlessly integrated into the bracelet. This monitor enables real-time data transmission to a smartphone via Bluetooth, enhancing usability and functionality.

Earlobe pulse oximeter

Earlobe pulse oximeter

This device offers an alternative placement on the ear. With a single touch, it provides accurate oxygen level readings. Its comfortable design ensures ease of use, allowing for hands-free operation and enabling users to carry out other activities during measurement.

Watch pulse oximeter

Watch pulse oximeter

Although this is a good option that provides programable oxygen monitoring, it has less accuracy due to excessive user movement.

Neonatal and pediatric pulse oximeters

Neonatal and pediatric pulse oximeters

This system is suitable for users who tend to stay in bed for prolonged periods. The device offers comfort during its use and is connected to a monitor that measures oxygen levels continuously.

Choosing the right pulse oximeter for seniors and caregivers

Seniors and caregivers can choose a pulse oximeter based on the user’s daily activities. If the senior is mostly resting on the bed, then a pediatric pulse oximeter would be the best bet since it can be used for prolonged periods and provides oxygen level measures continuously. However, if the user tends to realize more activities either indoors or outdoors, a handheld or wrist pulse oximeter might be a better option.

Understanding pulse oximeter readings and limitations

Usually, the percentage of oxygenated blood is displayed as SpO2 (saturation of peripheral oxygen). The percentage value on the device corresponds to the comparison between the total amount of hemoglobin in the blood vessels versus the amount of hemoglobin carrying oxygen. In healthy individuals, the value tends to be between 95 and 100%.

Although pulse oximeters are useful devices for measuring the body's oxygen levels and detecting heart rate, there are some factors that can influence their performance and the accuracy of readings.

Limitations related to users:

  • Excessive user movement
  • Low body temperature on extremities
  • Low iron levels (anemia)
  • Skin pigmentation

Limitations related to environmental factors:

  • Excessive light
  • Cold environment
  • High altitudes

The accuracy of pulse oximeters tends to be within 2-4% of the actual blood oxygen levels.

Final word

Technology is moving towards a miniaturization era, where different gadgets are being reduced in size and improved so that any person can use this technology anywhere, anytime. Pulse oximeters are a clear example of that. Do not be surprised if small pulse oximeters appear soon, as implantable technology.


📝Healthnews editor's top picks

Discover some of the best pulse oximeters on the market in our dedicated article. All of the products underwent a rigorous evaluation process by the Healthnews Research Team.

Oxiline Pressure 9 Pro
  • Measures pulse, blood oxygen levels, and perfusion index
  • Provides readings in under 10 seconds
  • Operated with one button
Simpro NatureSpirit OLCD Display Fingertip Pulse Oximeter
  • Measures pulse and blood oxygen levels
  • Can take measurements for up to 30 hours continuously
  • Clear reading display
Carex Finger Pulse Oximeter Oxygen Saturation Monitor
  • Measures pulse and blood oxygen levels
  • Provides readings in 10 seconds
  • Suitable for all ages, including children

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