Rebreather or Anesthesia machine?

[broncobowsher]

I imagine they utilize anesthesia machines in places like Santa Fe or Flagstaff, where the altitude is great enough that these differences matter.

Probably not looking at altitude/pressure. Calibrate to 21% air and 100% O2 and you will read 21% to 100% at that pressure. Think of it more as a basic Nitrox tester. FiO2 is still the fraction in the gas being sampled.

Now if you are trying to run an anesthesia machine in an unpressurized aircraft, or while driving up and down a mountain (Flagstaff to Phoenix) now you are going to have pressure related issues.

 

[rsingler]

Lots of good thoughts here, but as noted above, measuring sat is confounded by perfusion and some colors. While you can get around the color problem by selecting a body part through which to shine the light, you can’t avoid the fact that with the least bit of hypothermia (e.g., any diving) the body will vasoconstrict a sacrificial part like your fingertip or your ear such that its blood flow is so marginal, the SaO2 truly is hypoxic. If you are extrapolating to your central circulation from that part's perfusion, you will overestimate your hypoxia.

Also noteworthy is the time lag from central circulation to periphery. If you are hoping for a sat monitor to protect you from the consequences of a bad gas switch, you will likely be falling unconscious just as your ear or finger sat is starting to fall off the cliff. The red lights of your PPO2 in the HUD will give you a slightly earlier warning.

 

[doctormike]

What the man said ^

 

[KevinNM]

Interesting....
doesn't Poseidon solid state O2 sensor measure a color (I think its red) to read po2? I know that other solid state o2 sensors do that too. But are not rated very high in o2 percentages...

The O2 sat sensor is looking at the color of the body part it is attached to, typically a fingertip. Red nail polish is it’s sworn enemy.

The solid state oxygen sensor is looking at the actual gas. I don’t know how it works, but I doubt it is susceptible to the same sort of issue.

 

[kelemvor]

You and me both. Epidural for me. Let’s compare notes post-op.

Today's the day. Just stopped by to make sure I remembered the joke.

 

[tridacna]

Today's the day. Just stopped by to make sure I remembered the joke.

Mine's on the 22nd. Not getting Propofol..:-( Good luck.

 

[kelemvor]

Mine's on the 22nd. Not getting Propofol..:-( Good luck.

Well I tried it. Pretty sure I got the whole thing out before I went under. They didn't say anything about it and I forgot to mention it when I woke up.

Hope the injection starts doing the business soon. At the moment it hasn't helped.