Analysis of the ear pulse oximeter waveform.

Area of Science:

• Cardiovascular Physiology
• Medical Monitoring Devices
• Hemodynamic Analysis

Background:

• Understanding the relationship between central hemodynamics and peripheral waveforms is crucial for optimizing cardiac performance.
• Pulse oximeter waveforms, particularly from the ear and finger, are being investigated for their potential to reflect central hemodynamic status.

Purpose of the Study:

• To investigate the relationship between ear and finger pulse oximeter waveforms and cardiac output (CO).
• To assess the utility of peripheral plethysmographic waveforms in monitoring central hemodynamic changes and optimizing cardiac performance.

Main Methods:

• The study involved a cold immersion test on plethysmographic waveforms and correlation analysis with CO during CABG surgery.
• Ear and finger plethysmographic waveforms were analyzed for amplitude, width, area, upstroke, and downslope.
• Cardiac output was measured using a pulmonary artery catheter, and multi-linear regression was employed to correlate waveforms with CO and heart rate (HR).

Main Results:

• Cold immersion reduced finger plethysmographic waveforms but had minimal effect on ear waveforms, except for increased ear plethysmographic width.
• Significant correlations were found between ear plethysmographic width and other ear/finger waveforms, as well as with HR and CO.
• A multi-linear regression model was developed, but Bland & Altman analysis indicated a large bias and imprecision for clinical acceptance.

Conclusions:

• Ear plethysmographic waveforms are relatively unaffected by vasoconstrictive challenges, making them suitable for monitoring central hemodynamic changes.
• The width of the ear plethysmographic waveform demonstrates a good correlation with cardiac output.