azdj wrote:I have been using a Bipap ST from about 1month, with some improvement, but still general feeling of fatigue and poor sleep. My pressures are set at 14 / 10. While the information from the Bipap St smartcard and Encore viewer is helpful (it is not as detailed as the other M series machines, in particular it is poor at giving detailed apnea information), I thought is would be helpful to add a pulse oximeter to check the status of my oxyen saturation during the night. So I bough a PC68B Wrist Pulse Oximeter from Devon medical for $298. It is a good machine that will monitor sO2 and pulse continuously over the night (1, 3 or 8 second intervals) and allow a computer download and print-out of results. After using for several nights, I found some interesting (initial) results:
1. My oxygen saturations were falling into the 80s and even as low as high 70s during my ramp-up time and particularly just as I fell asleep towards the end of my ramp time. After full pressure was achieved, the results improved.
2. I was diagnosed with break-through centrals, hence the ST. The doc put me on a backup rate of 14, but said could decrease to 8-10 if necessary for comfort. I did that after a couple of weeks because my natural breath rate when awake is much lower than that and 14 was uncomfortable. However, the pulse oximeter together with my Encore results showed that when my breath rates was 10 or lower, my sO2 were going below 90%. I think I was breathing shallower in sleep than awake so even at the same breath rate, I was not sufficiently oxygenating at night.
3. My overall sO2 results were worse with my nasal mask than with my full face mask, even when the results were in the 90s, it appears the numbers are higher with full face. I will continue to monitor this over a longer time, but my initial thought is that the nasal mask is just not letting enough air through (especially during ramp up), or perhaps it was not exchanging CO2 quick enough. even at the same pressures. But for some reason, the full face mask seems to allow me to oxygenate better (and I don't think it was because of mouth leaks with the nasal mask - I use a chin strap and do not have dry mouth or other signs of mouth leak, and my leak rates are always consistent at 30 which is right on for my mask).
Based on this, I adjusted the ramp pressure to start at 8 rather than 4. I also increased the back-up rate to 11 and have started using the full face mask as preferred mask. Based on the last several nights, I have both slept much better and my oximeter results have shown no incidents of going beyond 90% over the entire night. Indeed, my results have generally run pretty consistently at 95% or better over the night, which I feel very good about.
based on this, I think that having an oximeter can be very useful. As many have said in this forum, we often are prescribed these therapies based on 1 or 2 nights sleep study with little follow-up. The more information we have, the better off we are. Certainly your O2 saturations are a critical part of therapy, and one that the machines will not give us directly. As long as I know my O2 sats are nomal, and I subjectively feel like I had good sleep, I feel my therapy is a success. I will also use the oximeter when I go up to my cabin at 8,000 feet to check my 02 sats at high altitude when using my machine, and to test my sats after a night out drinking, etc - all of those variables that 1 night at the sleep study doesn't check for!
Just thought you might find that interesting or helpful....
1. You were most likely mouth breathing while using the nasal mask, that would explain doing better on the Full Face mask.
2. Back up or Timed mode only kicks in when you are having a central apnea, so keeping the BPM higher would be advise, I mean if you slept "Normally" at a lower BPM rate you wouldn't need the machine would you? While it may appear uncomfortable you don't want to "mimic" mimic poor sleep with the back up rate, the idea is to get you breathing again where the machine switches back to Spontaneous mode, so any "Timed" mode should feel uncomfortable. I would try a 10-12 range backup rate.
3. Pulse Oximeter is a good idea, it can show you how you are doing separate from the machine. More important than SAO2, what is your pulse or heart rate doing after these periods of recover from low SAO2 levels? You might want to share that info with your Cardiologist.
4. What you experienced during Ramp is to be expected, and the sleep onset events after that expires, probably the first 30 minutes of sleep will be garbage. You might try lowering the Ramp timer, calculate it out based upon pressure/time if you are only 1 or 2 cm lower than it may not be helping you fall asleep at all.
5. You mention your pressure is 14/10? Interesting, very interesting, I wonder if that is not your problem. EPAP=10 and central apnea seems a bit high to me. Not knowing what your AHI is or what the PSG titration showed, I would be highly suspect of that EPAP setting.
IF there was any change I would make, it would be to pay attention to that heart rate, discuss it with your cardiologist if need be and if I felt I needed improvement I would lower EPAP from 10 to 9 and correlate SAO2 report, I would even try EPAP=8 and again watching what that SAO2 report looks like. Try to observe periods on the SAO2 report where oxygen levels are near baseline and note the heart rate. Then compare periods where SAO2 levels are down and heart rate is extremely low then races. You want to avoid the racing heart. If you are unsure, take a sample SAO2 report to your Cardiologist, they will circle the areas to avoid. Then you manipulate machine settings to avoid those conditions.
Those events at the onset of sleep, they are more likely shallow breathing or you simply relaxing so far where you forget to breathe. I would also expect mouth breathing to be associated with that more so with relaxation than congestion.
Sorry, I missed reading the paragraph above made bold. I see you found the reason for the low desats during ramp. Starting at 4 cm would starve you for air so that makes sense.
Just keep in mind if you have Central apnea, I would use caution increasing that EPAP pressure above 9 cm, reason I questioned it above. You are probably greater at risk of pressure induced central apnea then the general population, so even for them going above 10 cm can increase your risk of inducing central apnea. The one that counts is EPAP, while no one likes to use more pressure than needed doing so in your case could create a train wreck. Ideally, you want to observe AHI more specifically AI and adjust EPAP "just" to the point it reduces those down, but as you suggest your machine doesn't appear to provide that info. So without it you are in the dark, with known CA I would think you need to keep your EPAP at or below 9 cm. I wouldn't move above that without a PSG. IPAP or the top pressure should be increased only to encourage breathing by manipulation of volume and/or for hypopnea.
When you were on CPAP Auto, what was your pressure found there?
someday science will catch up to what I'm saying...