Desired SPO2 levels with oxygen systems

On the ground, I’m 98/99%.

But from FL65 to FL100 or so, I’m in the low 80’s. I don’t “feel” unwell. No headache, and don’t seem impared in decision making. Having said that, I will be tired that evening, but that seems to come with any flying, even lower level.

Colm

I’m on 98/99% on the ground and I aim for 95 on oxygen.
85 is a bit low. You better check you breathing technique. Do you use supplementary oxygen?

@Colm:

and don’t seem impared in decision making.

I thought I’m fine in decision making and calculating in the altitude chamber in Cologne. I was rubbish and quite alarming how wrong the difference between feeling and actual processes were. The problem is that you can’t feel hypoxia. Yes you have your signs, like my hands starts to tingle. A friend of mine does funny things (open the window and put his hand out in FL160), but his threshold is much lower than mine.

I’m 96-97% on the ground and 86-88% after less than an hour at 8500ft. A friend of similar age, weight and also a non smoker is always 3 or 4% higher than me in the air.
I nearly always suffered headaches after a 2-3 hour flight at 8-9000ft. Now I have the MH 02D2 oxygen system and have it set to start at FL50. It means I can now always try for higher levels, with the added benefits that brings.
Last year I did two flights totaling 6 ½ hours in one day, cruising mostly above 10,000ft. Something I wouldn’t have tried before oxygen, the oxygen used on those flights (two on oxy), only just moved the contents gauge.

Indeed mdoerr.

That I’ve wondered too. But I have tried the whole “mental maths” test with collegues at altitude. And I’ve had some weather challenging flights that I’ve had to rework in the air and seemed to manage fine too. But I do accept that fact that self analysis in that situation isn’t easy. All I can see is that I didn’t look back later and think “What the hell was I thinking?”

By the way this is without supplemental O2.

98-99% is normal for a non smoker at sea level. I have never known anyone who was ~95% but then I don’t go around measuring people with the oxymeter

Below 90%, it varies. Obviously it isn’t instant death otherwise all airline pilots (8000ft typical cabin) would be dead But they probably acclimatise over time. At ~500hrs/year, it must happen a bit. But then airline flying involves a highly automated cockpit these days, and the high aircraft performance removes a whole pile of “stress” issues which one gets in light GA when enroute.

At FL100, for me, oxygen makes a huge difference to tiredness.

I have never tried FL150-200 without oxygen and don’t want to do that in a plane, in case something bad happened.

I’ve noticed that when I put the oxymeter on my right index finger it indicates about 98% (at sea level). When I put it on my left index finger it indicates about 96%. I’ve tried this several times and it’s consistent. Does anyone know of an explanation for this? @MedEwok?

@Airborne_Again

There are several possible explanations. It is important to consider the underlying anatomy: The fingers get their blood mainly from two arteries, the A. radialis and A. ulnaris, who meet at in the hand and form a joint “hand artery”. From these, every finger is supplied by much smaller finger arteries, which ultimately transport the oxygen-rich blood to the fingertips. That is the point where you measure your SpO2.

In some humans, the A. radialis and A. ulnaris are not linked at all. These people will often have a slightly lower saturation by default, as their fingers only have one source of arterial blood instead of two. Many other “norm varieties” are possible, because our blood vessels differ significantly between individuals and even in the same individual over time, through injury, infection, regrowth etc.

Almost everyone develops some form of narrowing of their arteries over time (stenosis), supported by Western “industrial” diet, smoking, Diabetes, high blood cholesterol etc. This can occur anywhere between the heart and the fingertip (or anywhere else in the body for that matter, but that’s not relevant for the question at hand).

The difference in your SpO2 levels between the left and right index fingers can be caused by anatomical differences, arterial stenosis or even simply things such as the sensor fitting better on one hand than the other. Painted or artificial fingernails can lead to wrong measurements. Smoking can massively impact the values.

Try measuring on different fingers. I usually prefer the middle finger, because it seems to receive most blood from the two arteries. If the difference is consistent between both hands, narrower arteries leading to the hand with lower values are a possibility. If you experience no other symptoms, it is unlikely to have much pathological relevance. If you notice other symptoms, such as one hand being paler, feeling cold occasionally or even hurting, you should consult a doctor. There may be an underlying disease, such as Reynaud, present.

Airborne_Again wrote:

I’ve noticed that when I put the oxymeter on my right index finger it indicates about 98% (at sea level). When I put it on my left index finger it indicates about 96%.

All of what MedEwok wrote is obviously correct – I would just propose a much simpler explanation: I guess you are right handed, are you? Would not be surprising if callus on your left index finger is a bit thicker than on the right one – therefore reading can be a little lower.

btw.: The accuracy of typical consumer grade Pulsoximeters (e.g. the popular PO-200 line) is 2 Percentage points – therefore technically you have the same value on both fingers within the range of error

Malibuflyer wrote:

btw.: The accuracy of typical consumer grade Pulsoximeters (e.g. the popular PO-200 line) is 2 Percentage points – therefore technically you have the same value on both fingers within the range of error

Yes, but accuracy and repeatability are not the same thing. Repeatability is generally higher than accuracy for electronic devices. As I consistently get the same difference, it must be due to something else.