The sounds of saturation

Area of Science:

• Biomedical Engineering
• Anesthesiology
• Medical Device Technology

Background:

• Audible pulse tones from pulse oximeters aid anesthesiologists in monitoring oxygen saturation without constant visual display checks.
• The use of multiple pulse oximeter systems may compromise the reliable detection of oxygen saturation levels via audible tones.

Purpose of the Study:

• To investigate and compare the pitch frequency scales of audible pulse tones across different pulse oximeter manufacturers.
• To determine the relationship between oxygen saturation levels and corresponding pulse tone frequencies.

Main Methods:

• An observational study utilizing simulator technology to generate incremental oxygen saturation levels (80%-100%).
• Measurement of pulse tone frequencies using an oscilloscope.
• Analysis of the relationship between oxygen saturation and pulse tone frequency across various devices.

Main Results:

• Significant variations were observed in the pulse frequency scales employed by different pulse oximeter manufacturers.
• No two monitors exhibited the same pulse tone frequency at any tested oxygen saturation level between 80% and 100%.
• Diagrammed results visually confirmed the wide divergence in pulse tone frequency scales.

Conclusions:

• The substantial variation in pulse tone frequencies among pulse oximeter systems can impede accurate oxygen saturation assessment.
• Potential for confusion exists in clinical settings where multiple pulse oximeter systems are used.
• Anesthesiologists must be aware of and familiarize themselves with the specific audible frequency scale of each pulse oximeter model prior to use.