Pulse oximetry in the oesophagus.

Area of Science:

• Medical Devices
• Physiological Monitoring
• Biomedical Engineering

Background:

• Pulse oximetry is a vital non-invasive photometric technique for measuring arterial oxygen saturation (SpO(2)) and heart rate.
• Conventional pulse oximetry is unreliable in patients with poor peripheral perfusion due to compromised pulsatile flow at peripheral sites.
• Central blood flow may be preserved even when peripheral circulation is diminished.

Purpose of the Study:

• To explore the esophagus as an alternative site for pulse oximetry monitoring of SpO(2).
• To address the limitations of conventional pulse oximetry in compromised peripheral circulation.
• To present the development and clinical investigation of an esophageal pulse oximeter.

Main Methods:

• Review of the basic physics, technology, and applications of pulse oximetry and photoplethysmography.
• Development of a novel esophageal photoplethysmographic/SpO(2) probe.
• Investigation of the esophagus's suitability as an alternative monitoring site for continuous SpO(2) measurement.

Main Results:

• Conventional pulse oximetry fails in states of hypovolaemia, hypothermia, and vasoconstriction.
• The esophagus is proposed as a viable alternative site for SpO(2) monitoring.
• A new esophageal probe was developed and clinically investigated for continuous SpO(2) measurement.

Conclusions:

• The esophageal pulse oximeter demonstrates suitability for continuous SpO(2) monitoring in patients with poor peripheral circulation.
• This alternative monitoring site overcomes the limitations of traditional peripheral pulse oximetry.
• Further clinical investigations support the use of esophageal pulse oximetry in critical care settings.