SPO2 @ 12000 feet elevation (August 18-19, 2018)
I am monitoring SPO2 value during sleeping due to understanding the symptom of Sleep Apnea. This is an extra edition about SPO2!
(*) This is not much about Sleep Apnea....
SPO2 value in higher elevation
As I posted before, the reason I am interested in SPO2 / Pulse Oximeter which measures SPO2 is a relationship between SPO2 and elevation as a part of my hobby, climbing and hiking. When people in higher elevation, SPO2 value typically gets lower and it will be back to normal when people are acclimatized the elevation. Thus, SPO2 could be a good index to show the body response in higher elevation or low oxygen environment. Then, I found SPO2 value in my sleep study report and that was why I record SPO2 value during sleeping.
What does SPO2 value look like at 12,000 feet elevation?
I could not measure continuous measurement for SPO2 before since I do not have an equipment to do. However, I got one which can measure continuous SPO2 data during sleeping and I was thinking to measure it when I would be in higher elevation.
Finally, I had a chance to measure it. I went hiking to Mt. Whitney which is the highest mountain in California / USA. The elevation of the summit of Mt. Whitney is 14,505 feet. The camping site a day before the summit attempt is Trail Camp. The elevation of Trail Camp is about 12,000 feet where many people feel symptoms of high altitude sickness.
The chart on the top is the data, the average of SPO2 is 77%, the minimum is 60%. For a reference data, the chart below is the one a night before hiking.
Data at home (August 16-17, 2018)
The average is 95% and the minimum is 87%. Just looking at the number, the data at 12,000 feet elevation is very low. I have been using CPAP when I sleep and symptom of Sleep Apnea is getting improved. Although the lowest value of the night was 87, it might not be a true data. It might be due to contact between sensor and the body. The following is a data with a better resolution.
August 16-17 with a better resolution
If you look at the chart carefully, the data is discontinue right before dropped SPO2. Therefore, the data right after the discontinue might not be a correct measurement. If I look at a similar resolution of data in the high elevation, I do not see such discontinuous part except the part sensor was off the body.
August 18-19 data with a better resolution
Those are data I captured....
This is main topic of posting today!
First of all, I was wondering why dropping SPO2 to somewhere below 90% in a sleep study is concern. The typical duration of a drop is probably a few minutes, it is around 1 minute in my case.
On the other hand, the data in higher elevation (12,000 feet) is less than 90% almost all portion. (Plotting in red shows the value is less than 90%). However, I have never felt something wrong when I stayed there a several days. Therefore, I did not take seriously when my report of sleep study shows less than 90% drop.
If you look at the data carefully, the range of SPO2 value is much bigger in the high elevation. In fact, when I try to measure SPO2 in real time, the measured value is not really stable and it is hard to pick a number which value would be a reasonable measurement data. This is due to how people breath, such as deep breathing might help to improve the number. Also, it becomes unstable when we move. Anyhow, the fact is the SPO2 value is getting much lower when people are in a high altitude.
What I found out from the data, there is heart rate data with SPO2 trend. The average heart rate at 12,000 feet is 83.6 bpm, the minimum is 55 bpm and the maximum is 111 bpm. On the other hand, the data at home is average is 52.8 bpm , the minimum is 46 bpm and the maximum is 90 bpm. (The maximum heart rate at home might be a false data since the right before the maximum value, the data is discontinues). Even if we assume 90 bpm is true data, there is 30 bpm difference between the data at home and the data at 12,000.
Not only SPO2, but also heart rate is getting higher!
The data shows, SPO2 value is getting lower, however, due to low SPO2 in higher elevation, the heart rate is also getting higher. I am not a specialist in this area and this is all speculation. Increasing the volume of circulation, the total amount of oxygen could not be very low. Another word, I think the human body might have enough oxygen even if SPO2 shows lower value.
I checked SPO2 drop due to Sleep Apnea that the heart rate is increasing when SPO2 value is dropped. However, it is very short period and it is back to normal in a short time. It is very hard to seem how fast a human body responds it. But I guess it might be very low oxygen due to Sleep Apnea and this is the reason of bad impacts to your body.
Almost all cases people are in high altitude, the elevation is not suddenly up, it is slowly changed. Therefore it has enough time to adjust the circulation just looking into the SP value. Therefore the chance to get really low oxygen situation could be very small.
I was not aware of the difference, when I just looking at SPO2 value. Now I had a data in higher elevation. With that data, I realize Sleep Apnea would be one of serious symptom people need to get some treatment wither way.
This is an extra edition of Sleep Apnea for SPO2 value
