It seems that my joy in cutting down the number of apneic events by increasing the pressure that my CPAP machine provides was short lived: true, I had three days with few events at a pressure of 7.5 cmH2O, but then I had four days with high numbers (back into the realm of 20 incidents per hour). As per my instructions, I increased the pressure to 8 cmH2O. After a week, I checked the results and saw that increasing the pressure had made no difference.
Yesterday, I increased the pressure to 9 cmH2O; presumably as a result of trying to adapt to the higher pressure, I slept very badly and this morning I feel lousy. Hopefully I'll get used to the new pressure and get some sleep, although its quality will be an unknown factor.
In my doctoral studies, I was working on what's called the Mann-Whitney U test, which basically checks whether one series of values is significantly different from another series of values. This test is meant for non-standard distributed values which are independent of each other - exactly like the values I get from the CPAP machine. I checked 24 values from Friday nights against 24 values from Saturday nights, and assuming that I did the maths correctly, I can conclude with a confidence level of 95% that I have more apnea on a Friday night than on a Saturday.
The only good thing that I can find to say about my health is that my weight is fast decreasing. Two weeks ago I was surprised to discover that my weight had ballooned from 82 kg to 85 kg; last week it had decreased to 84.3 kg and this morning I weighed only 83.3 kg. At this rate, in another two weeks I will have lost all the extra weight and will be well placed to make some serious losses.
Which leads me back to sleep apnea: shortly my weight will be the same as it was in April when the machine was set up, which means that I should be using the same pressure as then (7 cmH2O). If there is a significant increase in the number of apneic events (without regard to pressure) then there is some other variable which needs to be taken into account. Maybe there is a problem with the machine or the mask ... or maybe me.
As an aside, I note that despite the fact that a sizeable proportion of the adult population suffers from sleep apnea, I have never seen this (or CPAP machines) mentioned in either films or books. So it was a happy moment when I found the following passage in the opening pages of 'Up in the air' "Once between Denver and Oklahoma City, I nodded off next to a pulmonary specialist who told me when I woke that I had apnea - a tendency to stop breathing while unconscious. The doctor recommended a machine that pushes air through the nostrils while one sleeps to raise the oxygen level in one's blood."
As an aside, I note that despite the fact that a sizeable proportion of the adult population suffers from sleep apnea, I have never seen this (or CPAP machines) mentioned in either films or books. So it was a happy moment when I found the following passage in the opening pages of 'Up in the air' "Once between Denver and Oklahoma City, I nodded off next to a pulmonary specialist who told me when I woke that I had apnea - a tendency to stop breathing while unconscious. The doctor recommended a machine that pushes air through the nostrils while one sleeps to raise the oxygen level in one's blood."
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