A pulse oximeter may look like a simple device, but the numbers on its screen provide useful information during patient monitoring. What are the 2 readings on a pulse oximeter? The two primary readings are SpO₂ (oxygen saturation) and pulse rate (PR). SpO₂ is shown as a percentage, while pulse rate is usually shown in beats per minute (bpm). Some devices may also display a third value, such as signal strength. (U.S. Food and Drug Administration [FDA], 2025)
Understanding these readings is important for healthcare staff who use patient monitoring equipment. It is also important to understand what can affect a reading and why properly maintained equipment matters.
What Are the 2 Readings on a Pulse Oximeter?
The two main readings on a pulse oximeter are:
- SpO₂: An estimate of oxygen saturation in the blood, shown as a percentage.
- PR: The detected pulse rate, usually shown in beats per minute.
A pulse oximeter is commonly clipped onto a fingertip. It uses light beams to estimate oxygen saturation and pulse rate without requiring a blood sample. (U.S. Food and Drug Administration [FDA], 2026)
These readings serve different purposes but are often displayed together to provide useful information during patient monitoring.
What Does SpO₂ Mean on a Pulse Oximeter?
SpO₂ refers to peripheral oxygen saturation. It is an estimate of how much oxygen is being carried in the blood.
The reading is displayed as a percentage. For example, a device may display SpO₂ 98%.
The FDA notes that oxygen saturation values are between 95% and 100% for most healthy individuals, although readings can vary based on a person’s health and other factors. A pulse oximeter reading should also be considered along with symptoms and other clinical information. (FDA, 2025)
It is important to remember that a pulse oximeter estimates oxygen saturation. It does not directly measure arterial blood oxygen.
How Does a Pulse Oximeter Measure SpO₂?
The device uses light beams from a sensor to estimate oxygen saturation. The sensor detects changes in light absorption associated with pulsating blood and the device processes these signals to produce the displayed SpO₂ value.
Because the reading depends on the detected signal, proper sensor placement and stable measurement conditions are important.
What Does the Pulse Rate Mean on a Pulse Oximeter?
The second primary reading is pulse rate, often labeled PR.
Pulse rate is generally displayed in beats per minute (bpm). For example, the screen may show PR 72 bpm.
This number represents the pulse detected by the pulse oximeter. It is different from the SpO₂ reading, which is expressed as a percentage.
Why Does a Pulse Oximeter Show Both SpO₂ and Pulse Rate?
Showing both readings gives healthcare professionals additional information during patient monitoring.
The SpO₂ reading provides an estimate of oxygen saturation, while the PR reading indicates the detected pulse rate. Looking at both readings can help provide a broader picture of the patient’s monitored status.
However, neither number should be viewed as a diagnosis on its own. Pulse oximeter readings should be interpreted in the proper clinical context.
How to Read a Pulse Oximeter Screen Correctly
Most pulse oximeter displays are designed to make the primary readings easy to identify.
Look for:
- SpO₂ — oxygen saturation percentage
- PR — pulse rate in bpm
- Additional indicators — depending on the device model
For example, a display might show:
SpO₂: 98%
PR: 72 bpm
Some devices may also show signal strength, a pulse waveform, battery information, or other indicators. These additional values should not be confused with the two primary readings.
Always follow the manufacturer’s instructions because display layouts and features can differ between models.
What Are the 2 Readings on a Pulse Oximeter and What Do They Mean?
In simple terms, the two primary readings answer two different questions:
| Reading | What It Shows | Common Display |
| SpO₂ | Estimated oxygen saturation | Percentage (%) |
| PR | Detected pulse rate | Beats per minute (bpm) |
Understanding the difference is especially important in healthcare environments where pulse oximeters are used as part of broader patient monitoring.
How Accurate Are Pulse Oximeter Readings?
Pulse oximeters are useful monitoring devices, but their readings are not always perfect.
The FDA identifies several factors that can affect pulse oximeter accuracy, including poor circulation, skin pigmentation, skin thickness, skin temperature, current tobacco use, and fingernail polish. (U.S. Food and Drug Administration [FDA], n.d.)
Movement, incorrect sensor placement, and other equipment-related issues can also affect the quality of the detected signal.
Why Can a Pulse Oximeter Give an Inaccurate Reading?
Potential causes can be grouped into three areas:
Patient factors:
Poor circulation, cold skin, and other physical conditions can affect the reading.
Use-related factors:
Movement, incorrect sensor placement, or fingernail polish can interfere with measurement.
Equipment factors:
Damaged sensors, worn cables, battery problems, display issues, or equipment faults can affect device performance.
This is why healthcare facilities need to consider both proper device use and proper equipment management.
How to Get a More Reliable Pulse Oximeter Reading
Good measurement practices can help reduce avoidable errors.
Keep the Sensor and Patient Still
Movement can interfere with the signal detected by the sensor. The FDA recommends remaining still and waiting until the reading stops changing before recording it. (FDA, 2025)
Follow Manufacturer Instructions
Each pulse oximeter has specific instructions for placement, operation, cleaning, and maintenance. Following these instructions helps support proper device performance.
Check the Equipment
Healthcare staff should also look for visible damage, loose connections, damaged sensors, cable problems, battery issues, and error messages.
If a device repeatedly produces unusual or inconsistent results, it may need professional inspection.
Why Pulse Oximeter Maintenance Matters for Reliable Patient Monitoring
Reliable patient monitoring depends on more than simply turning a device on and reading its screen. Medical equipment must also be inspected, maintained, tested, and repaired when needed.
Preventive maintenance can help facilities identify equipment problems before they cause unexpected downtime. Depending on the device and manufacturer’s requirements, service may include functional checks, performance verification, calibration support, repairs, and documentation.
For healthcare facilities, this approach can help maintain equipment reliability while supporting a more organized equipment-management program.
Pulse Oximeter Equipment Support for Accurate Patient Monitoring
Healthcare facilities often manage many types of patient monitoring equipment at the same time. When equipment develops faults or requires scheduled maintenance, having dependable biomedical support can help reduce disruption.
Syracuse Biomedical Services provides biomedical equipment services for healthcare facilities in Syracuse and surrounding Central New York communities. Its services include preventive maintenance, calibration, equipment testing, and on-site or in-house repair for a broad range of biomedical equipment and patient monitoring systems. (Syracuse Biomedical Services, 2026)
Preventive Maintenance for Patient Monitoring Equipment
Preventive maintenance focuses on identifying potential problems before equipment fails.
Depending on the equipment, maintenance may include:
- Routine inspections
- Functional testing
- Performance checks
- Calibration support
- Cleaning and servicing
- Documentation
- Early problem detection
SBS develops customized biomedical equipment programs based on a facility’s equipment and operational needs.
Equipment Testing and Performance Verification
Testing helps determine whether medical equipment is operating as expected.
Syracuse Biomedical Services provides equipment testing, performance verification, maintenance documentation, and compliance support for healthcare facilities. These records can help facilities track service history and maintain organized equipment-management processes. (Syracuse Biomedical Services, 2026)
Medical Equipment Repair and Troubleshooting
Professional repair may be appropriate when equipment has recurring errors, inconsistent performance, physical damage, or other operational problems.
SBS provides medical equipment repair and maintenance services for a broad range of clinical equipment, including patient monitoring systems. Its repair services can include diagnostic testing, functional testing, calibration where applicable, safety checks, and post-repair verification.
Need Reliable Biomedical Equipment Support?
Understanding the two readings on a pulse oximeter is only one part of effective patient monitoring. Healthcare facilities also need equipment that is properly maintained, tested, and ready for use.
Syracuse Biomedical Services supports healthcare facilities in Syracuse and throughout Central New York with biomedical equipment maintenance, preventive maintenance, testing, calibration support, repair, and documentation services.
If your facility needs help managing patient monitoring or other biomedical equipment, contact Syracuse Biomedical Services to discuss your equipment service needs and develop a support plan suited to your facility.
