Pulse Ox Sensors in Diving

[certainmisuse]

Hello,

Let's try this here with regard to rebreathers (CCR) although I must admit my personal motivation is for freediving. Let's just generalize the reason for wanting to use a Pulse Ox underwater in order to prevent of hypoxia. I have found a number of medical articles on this subject (including one out of the Duke Medical School) and I'm curious if anyone is aware of these devices being used in practice? It feels like implementation could be straightforward given the amount money put into smart watches with such technology. Take the Garmin Descent for example which I believe has the capability to take pulse ox readings but to my knowledge it is not paired with the diving app. currently. Thanks for any insight.

Regards,
David

 

[rjack321]

Are you a CCR diver? I see no good reason to add one more thing to monitor. Especially since it doesn't tell you anything that the ppO2 monitor(s) doesn't already tell you. And you need to know your ppO2 anyway.

 

[fmerkel]

I suspect it would be of little use.
1. They don't actually measure O2 level, or SaO2. They measure the color red, then translate that into SaO2, oxygenated blood being 'redder' than hypoxic blood.
2. The probe is critical, kind of like an antenna on a TV. If you don't have a good signal, adequate blood flow to the extremities, this will compromise the signal. Garbage in > garbage out. Cold fingers (assuming a finger probe...there are other types), and blood shift due to diving may interfere with the signal.
3. Serious challenges getting this to work underwater.
4. For free diving the change in effective ppO2 with ascent happens rapidly due to pressure changes. The blood has to get out to the probe during a circulatory cycle. This would likely trail behind blood to the brain. Kind of doubt your critical info would keep up with the monitoring system issues.

 

[certainmisuse]

I suspect it would be of little use.
1. They don't actually measure O2 level, or SaO2. They measure the color red, then translate that into SaO2, oxygenated blood being 'redder' than hypoxic blood.
2. The probe is critical, kind of like an antenna on a TV. If you don't have a good signal, adequate blood flow to the extremities, this will compromise the signal. Garbage in > garbage out. Cold fingers (assuming a finger probe...there are other types), and blood shift due to diving may interfere with the signal.
3. Serious challenges getting this to work underwater.
4. For free diving the change in effective ppO2 with ascent happens rapidly due to pressure changes. The blood has to get out to the probe during a circulatory cycle. This would likely trail behind blood to the brain. Kind of doubt your critical info would keep up with the monitoring system issues.

Good points, thanks. And the antenna analogy is good for me since I design them for a living, . Duke seems to have used a head sensor, and I believe they performed the experiments in a chamber; i.e., not underwater.

 

[lukeb]

I have almost zero knowledge of rebreathers, so excuse my ignorance. But I an EMT and use Pulse Ox sensors almost every day at work. For the limitations listed above, Pulse Oximetry is being considered less and less of a key vital sign to monitor. Capnography, the monitoring of exhaled CO2 using a nasal cannula, is currently the 'gold standard' for respiratory assessment in the modern emergency medical field. I wonder if that would have any application for CCR rebreathers? I imagine to utilize a cannula you would have to combine it with a full face mask.

Just a thought. And again, sorry for my rebreather ignorance!