SIGNAL EXTRACTION TECHNOLOGY®: WHERE "SOLVING THE UNSOLVABLE" STARTED

Twenty-four years ago, two young engineers asked themselves why pulse oximetry wouldn't work during patient motion and low perfusion–and by doing so, set a new course that created a revolution in patient monitoring.

OVERCOMING THE LIMITATIONS OF CONVENTIONAL PULSE OXIMETRY

Since its inception, pulse oximetry was plagued by unreliability when it was needed most–during patient motion and low perfusion. The industry had given up and considered the problem "unsolvable." Clinicians were forced to live with the results–excessive false alarms, delayed notification due to long averaging times, inaccurate data, and an inability to obtain data on the most critical patients.

Conventional pulse oximetry works under the assumption that by looking at only the pulse and normalizing the pulsating signal over the non-pulsating signal, oxygen saturation (SpO2) can be measured without calibration. Although this was a big step forward in the evolution of pulse oximetry, it has one major flaw–it assumes the only pulsating component is arterial blood. Unfortunately for conventional pulse oximetry, venous blood moves every time the patient moves or breathes. This causes conventional pulse oximeters to display false low or high SpO2 and pulse rates–resulting in false alarms as high as 90% in ICUs and recovery rooms.

THE CHOICE OF CLINICIANS IN THE WORLD'S LEADING HOSPITALS

Because of its unmatched reliability during challenging conditions of motion and low perfusion, clinicians at thousands of hospitals around the world count on Masimo SET® every day to help them care for patients. And while many leading hospitals have already integrated Masimo SET® pulse oximetry technology, more are converting every day.

These hospitals and clinicians trust Masimo SET® to help them deliver the most effective and efficient patient care possible. With fewer false alarms,1 clinicians can focus on the patients who need the most attention. With more trustworthy measurements, clinicians can more tightly control oxygenation levels. And with more timely detection of true events, clinicians can intervene earlier for better patient outcomes and improved patient safety.

Clinical Accuracy

VALIDATED BY INDEPENDENT AND OBJECTIVE RESEARCH

To date, more than 100 independent and objective studies have shown that Masimo SET® outperforms all other pulse oximetry technologies, providing clinicians with unmatched sensitivity and specificity to make critical patient care decisions.

Unleashing Breakthrough Performance

When Joe Kiani and Mohamed Diab looked at the same pulse oximetry signal differently than anyone had before, they created new possibilities. By employing advanced signal processing techniques–including parallel engines and adaptive filters–they believed they could find the true arterial signal that would allow accurate monitoring of arterial oxygen saturation and pulse rate, even during the most challenging conditions. Signal Extraction Technology, or Masimo SET®, assumes that both the arterial and venous blood can move and uses parallel signal processing engines–DST®, FST®, SST, and MST–to separate the arterial signal from sources of noise (including the venous signal) to measure SpO2 and pulse rate accurately, even during motion.

After six years of dedicated and focused research and development, Masimo SET® debuted in 1995 at the Society for Technology in Anesthesia and won the prestigious Excellence in Technology Innovation Award. Thereafter, skeptical clinicians around the world sought actively to compare Masimo SET® to the best pulse oximetry technologies other companies had to offer. But in study after study, the breakthrough signal processing of Masimo SET® consistently resulted in significantly fewer false alarms and far superior true alarm detection.

Conventional pulse oximetry uses the standard red over infrared algorithm to provide SpO2, while Masimo SET® uses that conventional algorithm but has added four other algorithms that all run in parallel. These algorithms allow the distinction between arterial and venous signal during motion and low perfusion by identifying and isolating the non-arterial and venous noise SpO2 (left peak shown in blue) from the true arterial SpO2 components (right peak shown in red) in the signal. The plot peak on the right is then chosen as the SpO2 value, since the physiologically higher SpO2 value within the measuring site will be arterial signal.

With Masimo SET®, false alarms have been reduced by over 95%, while true alarm detection has increased to over 97%–even during conditions of motion and low perfusion.2

True Alarm Performance During Motion and Low Perfusion

False Alarm Performance During Motion and Low Perfusion

In this hospital-based study, investigators measured SpO2 in 10 subjects during motion and low perfusion conditions and calculated the false alarm rate during 120 full oxygenation events (specificity) and true alarm rate during 40 de-oxygenated events (sensitivity).2

Proven with Children3

This study measured missed true desaturation events out of 75 true events on 5 children undergoing evaluation for sleep-disordered breathing.

Proven with Infants4

Performance During Motion and Low Perfusion1

A total of 70 volunteers were tested with motorized hand motions. Each motion was studied during both room air breathing and hypoxemia. Pulse oximeters on the stationary hand were used to provide control measurements for comparison. Sensitivity was defined as ability to detect a true SpO2 <90%. Specificity was defined as the ability to detect a true SpO2 >90%.

REFERENCES

  • 1 Barker SJ. Anesth Analg. 2002 Oct;95(4):967-72.
  • 2 Shah N., Ragaswamy H.B., Govindugari K., Estanol L. J Clin Anesth. 2012 Aug;24(5):385-91.
  • 3 Brouillette RT, Lavergne J, Leimanis A, Nixon GM, Laden S, McGregor CD. Differences in Pulse Oximetry Technology can Affect Detection of Sleep Disordered Breathing in Children. Anesth Analg. 2002; 94:S47-S53
  • 4 Hay WW, Rodden DJ, Collins SM, Melara DL, Hale KA, Fashaw LM. Reliability of conventional and new oximetry in neonatal patients. Journal of Perinatology. 2002; 22:360-266