Nonpulsatile and noninvasive transmittance and reflectance tissue-bed oximetry.

Area of Science:

• Biomedical Engineering
• Medical Devices
• Neonatal Care

Background:

• Conventional pulse oximeters require a detectable pulse, limiting their use in neonates and small subjects with weak or absent pulses.
• A previously developed optical device measured blood pressure noninvasively in small subjects.
• Measuring oxygen saturation (SaO2) noninvasively is crucial for monitoring vulnerable populations.

Purpose of the Study:

• To integrate SaO2 measurement capability into an existing noninvasive optical blood pressure device.
• To establish a calibration curve for SaO2 measurements using the enhanced device.
• To compare the efficacy of transmittance versus reflectance methods for SaO2 determination.

Main Methods:

• An optical device was modified to measure SaO2.
• Eleven pigs (20-27 kg) were used for in vivo testing, with measurements taken on the pig tail.
• Arterial blood samples were analyzed using a blood-gas analyzer for SaO2 reference values.
• A blood-pressure cuff was employed to occlude blood flow, creating a bloodless optical path for method comparison.

Main Results:

• The enhanced optical device successfully measured SaO2 noninvasively across a wide range (4% to 100%).
• Both transmittance and reflectance measurement methods demonstrated reliable SaO2 readings.
• The device's ability to function without requiring a pulse was validated.

Conclusions:

• The developed optical device effectively measures SaO2 noninvasively in subjects with or without a pulse.
• Both transmittance and reflectance methods are suitable for SaO2 assessment using this technology.
• This device offers a valuable tool for neonatal and small animal monitoring.