What's your oxygen saturation?

[yak53]

Anyone else have a similar experience to what I mentioned in post #14?

If my particular meter, or brand, was bad, and its not a general trend, then I may consider buying a new one.

I became pretty convinced its indications at altitude were meaningless when I turned the O2 on in my glider and my SaO2 only went from 86 to 88.
Its also pretty strange to be out hiking in the mountains, feeling great, and the stupid meter says 86.

Just curious if anyone else has had a meter that seemed to be affected by altitude.

How a Pulse OX works from Wikipedia,
One LED is red, with wavelength of 660 nm, and the other is infrared, 905, 910, or 940 nm. Absorption at these wavelengths differs significantly between oxyhemoglobin and its deoxygenated form; therefore, the oxy/deoxyhemoglobin ratio can be calculated from the ratio of the absorption of the red and infrared light. The absorbance of oxyhemoglobin and deoxyhemoglobin is the same (isosbestic point) for the wavelengths of 590 and 805 nm; earlier oximeters used these wavelengths for correction for hemoglobin concentration.[2]

Pulse OX works by measuring the change in the light absorbency at 660nm and 905, 910, or 940 nm. Which should not be affected by altitude.
Your body will have different oxygenation levels at different altitudes, due to the lowers partial pressure of oxygen.

Altitude (feet)
0 5000 10000 12000 13000 14000 15000 20000 25000

Atmospheric Pressure (mm Hg)
760 632 523 483 465 447 429 350 282

Ambient O2 (mm Hg)
159 133 110 101 97 94 90 73 59

Table 2. Partial pressures of oxygen in dry air for representative pressure altitudes

The software in the Pulse OX is the biggest difference between units. Every manufacturer has different software, some is better than others in marginal conditions such as, movement, high ambient light, low blood flow in you finger, nail polish, are a few thing that will affect the reading. Many quality medical units cost thousands but use disposable finger, ear or nose probes.

Their are a number of things that can affect the Pulse OX changes at altitude, your age, your physical health, your fitness level, your smoking history. When you add oxygen, if you are in good heath, your Pulse OX should return to you baseline reading at moderate altitudes. Some people live at a Pulse OX of 88% due to lung disease. Assuming your baseline is normal above 95%. It may due to your Oxygen delivery method. I assume you were using a Nasal cannula at a 2 liter per minute flow. Which would mean you are breathing about 27% not 100% oxygen. Assuming you were at 15000 ft your partial pressure of oxygen is 90 not 159 at sea level. By adding 27% oxygen you increase your partial pressure of oxygen to 115 which is equal to about 6500 feet but still less than 159 you would expect at sea level. The highest percent oxygen that can be delivered, with out the danger of a pure oxygen environment or having an endotracial tube is a properly fitted non re-breather face mask running 15 liters per minute of oxygen which only will get you to 74% oxygen and blow through your on board oxygen in less than 15 minutes.

 

[rockwoodrv9]

New suggested oxygen meters?

Reviving an old thread.

I am looking for a finger oxygen testing unit. I have found several for around $30-$40. Since it is possible to bet your life on how accurate it is, does anyone have experience with a unit that works well?

Thanks

 

[flightlogic]

cheap pulse ox and variable quality

This may not really help... but I will mention two units. The first I had was the $35 unit from China. (ebaY) In sunlight, it was swamped with IR and read poorly. In shade, I could get comparative readings OK... as I started up the oxygen and adjusted it. I still did not count on the percentage reading to be very accurate.
Eventually, I found a Nonin... brand that was a surplus sale from Army issue. It was used in Blackhawks as standard issue. I paid around $85. It is immune from IR interference and shuts off after use. I find the readings steady and accurate. One trick a surgeon showed my wife was to turn it 90 degrees if she had nail polish on. The light beam was then going side to side through her finger. That solved the lack of readings for her fingers.
The point I remember is this... try a cheap one. If it is working and compares to known readings from a good unit, keep it. If not, it is such a small investment... ditch it and upgrade if possible. Do some pretty extensive comparisons in flight with oxy flow settings and the results at your finger.
If in doubt, always go a bit higher with flow rates. It is very cheap insurance for safety... and it can even kill a headache. Well worth it in my view.

 

[David Paule]

I've got an "Easy@Home Deluxe Fingertip Pulse Oximeter with OLED Display in 4 Directions and 6 Modes, EHP50D1"

I like it a lot, but it might be hard to read in direct sunlight. Tried it on a recent run and had difficulties.

I might get another to replace my otherwise good Nonin, which unfortunately doesn't shut itself off, so I'm forced to remove the batteries after each flight.

Lost the battery cover once and Nonin replaced it remarkably quickly.

Dave

 

[catmandu]

I bought this one three years ago based on the review posted by a doctor who tested it against the one being used in an OR and found it to be accurate. Only reads in one direction, sometimes I need to find shade in the cockpit to be able to read the LED's, but for $18 I can't complain too much. It does shut off automatically which is nice, still on my first set of batteries.

 

[brad walton]

I bought mine from Anti-Splat Aero. Itseems to give the saturation numbers I expect at various levels of exercise and altitude. I strive for 94% saturation or better and arrive with better mental sharpness, less tired and no dull headache. $33.00

 

[AAflyer]

Alarms?

Has anyone found one that can be wired to one of the sensor inputs of a Dynon SkyView? I was thinking it could be coupled to a programmed alarm setting.