(06-20-2016, 06:43 PM)nativedancer Wrote: is there a recommended pressure support range in the st mode? should my 5.2 be less or more? ... Doc had me at 20/12 originally, but that was a bit much, made for numerous leaks.
Hi nativedancer,
If you don't already own one and can afford it, I recommend buying a recording pulse oximeter to use to optimize how much Pressure Support (PS) you are using. (No prescription is needed, and the kind which is worn like a wrist watch with separate finger sensor cup is more comfortable to wear all night.) I think that it is important that the PS not be too high or too low, and that your prescribed PS of 8 may be too high and your present PS of 5.2 is likely too low.
If the PS is high (like 8) and if we have normal healthy lungs, the high PS would be doing for us the great majority of the work of breathing. (For example, my ASV machine is able to automatically quickly adjust PS as high as necessary whenever I start to have a central apnea; when I'm breathing normally it stays at its Min PS setting around 5, but when I stop breathing PS raises itself to around 9 or 10 in order to do for me all the work of breathing.)
The higher the setting for PS, the more deeply we will tend to breathe in all night, and the higher will tend to be our average Tidal Volume (TV, the volume of air breathed each breath) and Minute Volume (MV, the volume of air breathed each minute, which is simply the average Tidal Volume times the number of breaths per minute).
If our PS setting is raised, this would tend to raise the average amount of Oxygen (O2) in our blood, because we will be breathing more deeply.
However, I think it is possible to have too much O2 in our blood.
On a standard ST machine (unlike on an ASV machine) the PS does not self adjust and if it is set low, like 5, it is likely our blood O2 saturation may be dropping to 88% or lower during the times we are having central events.
If our blood O2 saturation percentage (SpO2) is 98% or higher almost all of the night, I suspect it may be too high, causing unnecessarily higher oxidative stress (more prevalent creation of free radicals), leading to long term health problems and perhaps also interfering with medications we may be taking.
Regarding the average SpO2, not counting the occasional dips which occur during apnea events, I think an average SpO2 of around 94% to 96% would be ideal if we don't have COPD. For some types of COPD (Chronic Obstructive Pulmonary Disease) it is very dangerous to have high SpO2 and a safer target for SpO2 may be 89% to 91%.
Take care,
--- Vaughn
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