I spend about half my work time at 2,500 feet above sea level. The other half of the time I am at 14,000 above sea level. I recently had a lung infection that put me out of altitude work for two months. I've since been cleared for high altitude duty, and was given a prescription for a pulse oximeter. I've been carrying it around ever since.
Yesterday I was working at our 14,000 foot site, so I used the opportunity to make several spot checks. After a fairly strenuous project I took a reading and got a pulse rate of 134bpm and a blood saturation level of 74%. I was able to use pressure breathing to get my blood saturation back into the low 90's range without the use of medicinal oxygen. It took a while to get my pulse down below 100bpm. 90-100bpm is typical for me when resting at altitude.
As soon as I finish typing this I am going to call my doctor to discuss a course of action (e.g. monitoring and logging, limits, etc.) but I wanted to ask here as well: What are the practical limits on pulse rate and blood oxygen saturation when working at altitude? I do have some flexibility in my work schedule to take breaks and if necessary go on oxygen, so this would have immediate application for me.
Still working on this, but I've got an answer on the blood oxygen saturation: 90%. So that 74% was decidedly low. At my doctor's request I started logging my readings throughout the day. So far my worst low was a 69% saturation.
But something nice came out of this: One technique for raising your blood oxygen level at altitude is something called "pressure breathing". The idea is to artificially raise the pressure of the air in your lungs by pursing your lips to slow the air escaping while exhaling HARD. It's very counter-intuitive, but it works great. One minute of pressure breathing is typically enough to raise my oxygen level from the low 70's to the mid 90's. It works.