I know that altitude has been covered before, but my question is slightly different.
I'm planning a trip to a place which is at 3500m above sea level - and that's before I've set foot on a mountain. I had googled the subject pretty extensively, and seemed to come up with positive results - even the BMJ says 'asthmatics do well at altitude' as there are generally less allergens around.
However... my doctor is concerned what would happen to my oxygen levels if I had an attack where there was already substantially less oxygen that normal. Nothing on the internet had mentioned this very logical worry!
He explained the shape of the hemoglobin saturation curve, and how it suddenly drops off - so to start at lower oxygen, I'd be far nearer the drop-off point.
A fantastic website called altitude.org has explained quite a lot about how altitude affects our blood gases, but is anyone able to add any information - scientific or personal - about what could happen during an asthma attack at altitude.
At 3500m above sea level, there is 66% amount of oxygen as of at sea level, and your lungs will be working twice as hard. However at 2500m, where someone is unlikely to get symptoms of altitude sickness, there is 74% of oxygen available, so although 74% sounds very low, it isn't that bad really. If I were to trek to 6000m, there would be 48% of oxygen around. A fit healthy person on the top of Kilimanjaro at 5895m will have sats around 94. At 7135m (the base of a mountain in the area I'm going to - don't worry, I wont do it) someones sats would be at 73% at rest.
One final question - has anyone been at or over 3500m? Were you confident that you'd recognise the difference between breathlessness from asthma and altitude-related-illness which can be very serious? (Clearly asthma is very serious, but if you leave altitude illness alone and keep going up, you're in big trouble).
Clearly I'm planning a foolish trip, and I recognise that there is an unnecessarily high risk of problems by putting myself in that situation, and I understand that my doctor does not recommend it. But I'm also a headstrong person, and I want to go to this area more than anywhere else in the world. I understand that no one on this forum is likely to advise me to go, but can anyone offer any advice or info?
Thanks v much. C x