Summary
Pulse oximeter manufacturers frequently use "tissue oxygenation monitoring" and "tissue oxygen" in advertising brochures, press releases and regulatory submissions to describe pulse oximeter technology. The phrases are intended to describe that pulse oximeters measure delivery of oxygen to tissue. Pulse oximeter companies have not claimed this technology measures the consumption side of tissue oxygenation. However, many clinicians are confused when pulse oximeters claim to measure tissue oxygenation because they think pulse oximeters measure the same parameter as the InSpectraTM StO2 Measurement. And, of course, they do not. For a description of how InSpectraTMStO2 differs from pulse oximeters, refer to FAQ: How is InSpectra™ StO2 different from SpO2 and SaO2)?
Advanced pulse oximeters measure more than arterial oxygen saturation (SpO2). They also measure perfusion index (an indication of perfusion from low to high), and blood hemoglobin (only from Masimo). Because these parameters measure the delivery side of tissue oxygenation, pulse oximeter companies use the phrase “tissue oxygenation monitoring”. Without measuring of the consumption side of tissue oxygenation, pulse oximeters don't tell clinicians whether the delivered oxygen is adequate to meet tissue oxygen demand. InSpectra™ StO2 overcomes that limitation because it is a measure of the balance between oxygen delivery and consumption. This is an important distinction during hypoperfused conditions and shock assessment.