Most Accurate Pulse Oximeter Technology
Pulse oximeters with Masimo Signal Extraction Technology (SET) are the most accurate, particularly during challenging clinical conditions such as patient motion and poor perfusion, with sensitivity and specificity over 95% compared to conventional pulse oximeters. 1, 2
Understanding Pulse Oximeter Technology and Accuracy
How Pulse Oximeters Work
Pulse oximeters detect variations in light transmission of two different wavelengths that occur with arterial pulsations in an extremity (usually finger or ear lobe). Because oxygenated and reduced hemoglobin transmit certain light wavelengths differently, this information is used to estimate arterial oxygen saturation 3.
Accuracy Considerations
- Standard pulse oximeters have reasonable accuracy with 95% confidence limits of 4-5% compared with directly measured arterial oxygen saturation 3
- Accuracy is generally lower at saturations below 88% 3
- Modern pulse oximeters can measure heart rate and SpO₂ reliably after 90 seconds from application when designed to reduce movement artifact 3
Factors Affecting Pulse Oximeter Accuracy
Technical Limitations
- Movement artifacts significantly reduce measurement accuracy 1, 2
- Poor peripheral perfusion can yield falsely low readings 3
- Stray light and ambient noise can interfere with readings 3
- Dark skin color can interfere with signal detection, though newer technologies have addressed this issue 3, 4
Clinical Limitations
- Cannot detect carboxyhemoglobin or methemoglobin 3, 5
- Measures arterial oxygen saturation rather than PO₂, which limits utility in assessing effects of lung disease on gas exchange 3
- Some pulse oximeters tend to overestimate true arterial oxygen saturation 3
Advanced Pulse Oximeter Technologies
Masimo Signal Extraction Technology (SET)
- Employs advanced techniques including radiofrequency and light-shielded optical sensors, digital signal processing, and adaptive filtration 1
- Uses a discrete saturation transform (DST) to isolate individual "saturation components" in the optical pathway 1
- Reduces false alarms due to motion artifact from up to 90% to less than 5% 2
- Shows no clinically significant differences in accuracy between Black and White subjects in controlled laboratory settings 4
Other Advanced Technologies
- Newer pulse oximeters are less susceptible to motion artifacts and change tone with changes in hemoglobin saturation 3
- Some manufacturers have produced nasal cannulae that allow simultaneous delivery of oxygen and measurement of expired carbon dioxide 3
Best Practices for Pulse Oximeter Use
Probe Placement
- Finger probes are recommended over nose, ear, or forehead probes in patients with poor peripheral perfusion 6
- Applying the oximeter probe to the subject before connecting it to the instrument produces reliable results more quickly 3
- Proper positioning is critical; clip-on devices are easy to displace, which may produce artifactual data 3
Interpretation Guidelines
- Pulse oximetry should be used in conjunction with clinical assessment, not as a replacement 3
- Periodic validation against arterial blood gas measurements is important, especially for significant desaturation (change in SpO₂ ≥5%) 3
- Pulse oximetry is good for monitoring trending phenomena but not reliable for determining absolute magnitude of change 3
Conclusion
When selecting a pulse oximeter for clinical use, devices with Masimo Signal Extraction Technology provide superior accuracy during challenging clinical conditions. However, regardless of the technology used, understanding the limitations of pulse oximetry and using it as part of a comprehensive assessment rather than in isolation is essential for optimal patient care.