I am trying to figure out why most hospital it still seems to predominantly use fingertip sensor (LED+photodiode) based oximeter for SpO2. I tried searching for example of FDA 510(k) cleared oximeter devices, and there were at least a few dozen (>50) oximeter with fingertip sensor. There are only a dozen or two (at most) wrist sensor based oximeter that are FDA 510(k) approved. There are even less ring sensor and chest patch based oximeter (probably one or two each) that are FDA 510(k) cleared.
Are there any US hospitals that rely on wrist sensor based oximeter? My question is specific to the sensor (LED and photodiode) placement, and not on the placement of electronics itself. For example, Masimo RadiusPPG, Nonin 3150, etc. all use sensor in the fingertip. Oximeter which has electronics in the wrist but sensor coming via. wire to the fingertip is not considered fully wrist oximeter. I am curious to know how commonly do US hospitals use completely wrist (sensor on the wrist), or ring (sensor on the ring) or chest (sensor on the chest) based oximeter devices? Why is this not a clinically acceptable and popular practice?
How does this practice differ in general ward, intensive or critical care unit, out-patient setting, etc.? Does anyone have any survey data or information on this?