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[Treatment] Nearly new ASV machine settings
Thanks for the posts, I will see what happens with the respirologist soon, I will write up the experience I have had....it has been quite the trip...lol

One day at a time...


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Hi Storywizard,
Great job, you have been through so much and just kept right on going, keep up the good work.
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(05-23-2015, 08:58 PM)storywizard Wrote: Thanks for the posts, I will see what happens with the respirologist soon, I will write up the experience I have had....it has been quite the trip...lol

One day at a time...

Hi Story,

Good going and congratulations.

Meanwhile, regarding the one day at a time part:

If the EPAP is too low and is allowing some degree of obstruction in the airway the machine in "ASV" therapy mode responds the same as for central events - it raises PS in order to maintain a target (lower limit) for Minute Volume (targeting slightly less than your recent MV).

Minute Volume is how much air we breathe in or out during one minute. MV is also equal to the Respiration Rate (breaths per minute) times the Tidal Volume (TV or Vt). The Vt is the average volume of air we breathe in or out, each breath.

If some amount of obstruction is occurring the MV will tend to drop and the PS will tend to rise in order to increase the MV at least back to the target MV. The high PS may be getting air into your lungs all right, but an EPAP pressure which is too low will tend to inhibit exhalation to some degree, so you might not be exhaling fully.

If you find yourself gurgling or snoring only while exhaling, this is an indication that EPAP is lower than would be needed to keep your airway fully unobstructed during exhalation.

You would also be able to see in the Flow waveform when this is happening; at these times the Flow during exhalation will be jerky or stop-and-go.

If you have a recording pulse oximeter which is comfortable enough to wear one night every week (the wrist worn ones with separate finger sensor cup are more comfortable) then I would suggest monitoring your SpO2 each week (or more often if something changes, such as a change in prescription medications) to verify it is averaging approximately 94% to 96%, not paying much attention to short dips lower than the average unless lower than 90%. Raising the Min PS will tend to raise the MV and the average SpO2.

Something to keep in mind is that the "target" for Minute Volume (which the machine uses to decide whether to respond) is based only on the recent MV. We cannot set an absolute low limit for MV which the machine should stay above, and therefore a very slow reduction in MV will not be taken into account by the ResMed ASV algorithm. If obstruction grows very gradually and slowly prevents us from exhaling fully, the gradual reduction in MV might not be noticed by the machine, which could result in our SpO2 dropping too low, resulting in an arousal.

If this happens, raising EPAP would probably avoid the problem altogether. Also, since raising the Min PS will tend to raise the MV and the average SpO2, raising the Min PS might help some.

If higher pressure would be a problem, often the higher pressure is only needed when we are sleeping in the supine position (sleeping flat on our back), so taking precautions to not allow supine sleeping may also avoid the need for higher pressures.

Take care,
--- Vaughn
Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment. The Advisory Member group provides advice and suggestions to Apnea Board administrators and staff on matters concerning Apnea Board operation and administrative policies - not on matters concerning treatment for Sleep Apnea. I think it is now too late to change the name of the group but I think Voting Member group would perhaps have been a more descriptive name for the group.
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Thanks Vaughn for the ASV pressure education...I really appreciate it..I was starting to wonder what all that "other" stuff in SH was...now I am starting to know..

Thanks again...

all the best,

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