Note! This article does not constitute medical advice. It is simply a starting point for collecting information, so that you can be an informed medical consumer when you speak to a qualified physician.
In 2007 I'm doing the first part of the trip solo, so I bought my own pulse oximeter, mostly for fun, but just in case. At least at sea level my saturation is normal, although my heart rate in the photo is pretty high, thanks to just having been hauling around my gear. I'll hold off endorsing the brand I purchased until I see how well it does during the trip.
For reference, here is a record of my oxygen saturation and heart rate in 2005 and 2006. My heart rate tends to be a little fast for my level of fitness, so comparably fit people may have a lower rate. Also, keep in mind that there is not a direct correlation between these numbers and your likelihood of summiting. I was near the low side of fitness as measured by these metrics in 2005, but not at the bottom of my team, and everyone else summitted. All tests were done in the morning at rest. My figures in 2006 were much better at the lower elevations, probably due to my acclimatization from climbing El Plata. At Nido, my saturation wasn't great, but my heart rate was better, maybe due to my marathon training.
|Location||Oxygen Saturation (%) 2005||Heart rate (beats/min) 2005||Oxygen Saturation (%) 2006||Heart rate (beats/min) 2006|
|rest day in Base Camp (4.200 mts)||82||100||92||100|
|Base Camp / carry to Camp I / Base Camp||85||103||90||100|
|Base Camp / carry Camp II / Base Camp||81||100||95||100|
|rest day Base Camp||80||103||88||110|
|Camp I (4.850 mts)||84||108||86||102|
|Camp II (5,400 mts)||79||117||78||99|
|Camp III (5.800 mts)||75||115||.||.|
|summit day (morning camp III)||74||112||.||.|
One condition that is common, scary, but not a cause for concern is Cheyne-Stokes breathing: where the body stops breathing for half a minute or so during sleep. The hiker will wake up suddenly, feeling like he has been suffocating. It's scary if you haven't experienced it before. But it is generally not a cause for concern. Although it may not completely go away, it does seem (at least for me) to become less frequent with time, and its harmless, other than the loss of sleep it causes. It also appears to be more common with the onset of sleep. More information
Another common problem is distinguishing between altitude sickness and cerebral edema. Cerebral edema is relatively rare on Aconcagua, but serious and rapidly fatal, if evacuation isn't done quickly. The problem is that significant dizzyness and headache seem to indicate both edema and simple altitude sickness. One discriminating indication is oxygen saturation. Someone with cerebral edema is more likely to have very low saturation. Someone with headache and dizzyness but decent saturation may not have edema. Yet another complication is that altitude sickness can turn into cerebral edema. An experienced guide is your best bet to figuring this out. A doctor without high altitude experience may know little more than a layman in this context. Of course, having a doctor with high altitude treatment experience would be the best, and on Everest it appears that larger expeditions try to build such a team.
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