Disadvantage of high pressures

[ProfessorEd]

What disadvantages are there to a higher pressure than the minimum needed to lower the apnea/hyena level to below, say 5.

Occasionally when falling to sleep I find myself waking up with a deep breath (sometimes followed by fast breathing). I believe this to be an awakening caused by my windpipe collapsing right after the start of sleep. While I have an auto bipap which will presumably eventually raise the pressure if it starts out too low, it occurs to me that it might pay to have the pressure high enough so that no adjustments normally occur while sleep. This would eliminate the apneas that occur while the machine is adjusting the pressure. What are the advantages and disadvantages to this?

An obvious disadvantage is more discomfort and greater risk of mouth leakage.

The only medical argument I have seen is a reference to adverse effects from high oxygen partial pressures. While these studies were presumably done with normal pressures and oxygen enrichment, raising the pressure does raise the oxygen partial pressure also, although I suspect this would be a small effect in the ranges being discussed (say from 10 to 12).

What I have been look for is a “manual” on how to pick the pressure. I have not found this although I assume it must exist in training materials for sleep lab technicians or in the medical literature. Does anyone have a reference to such a document?

[ww]

I am also new to CPAP therapy. I have an auto PAP and started out with a OptiLife nasal pillow mask. Nothing seemed to work the way I thought it should!

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I learned first you have to stop mouth leakage. I repeat, first you have to stop mouth leakage completely!!! It took a ResMed Ultra Mirage Small Full Face Mask!!!

You need to add your equipment to your profile before anyone can help you much. If you have a data capable auto PAP, then you own the equipment to write the manual.

My titration was 7 cm, and after two months of reading the smartcard and looking at the software results, I am now at 10.5 cm.

Next, you need to get a card reader and the software to read the data from your machine so you can see what is happening on a daily basis. If you have a titrated value from your sleep study, learn how to set your machine pressure and set the bottom end at the titrated value and the top value about 4 cm above that. Look at the data daily or set the machine up as a CPAP at your titrated value and increase the value 1 cm each week while looking carefully at the data for that week.

If you had centrals on your sleep study, be extremely carefully about going above 10cm pressure as that may cause rather than eliminate apneas.

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CPAPopedia Keywords Contained In This Post (Click For Definition): resmed, mirage, nasal pillow, Titration, CPAP, auto

[cflame1]

Ed,
What range do you usually use? Do you have the software? What's your PS set to?

With myself, I find that I have to have my minimum EPAP set high enough or I wake up during the night.

If you don't have your minimum pressures set high enough the machine will take longer to respond to what's going on.

[ozij]

If you have a titrated value from your sleep study, learn how to set your machine pressure and set the bottom end at the titrated value and the top value about 4 cm above that.

ProfessorEd, I doubt a lab tech's training manual will help you. Lab techs see people for one night, in very strange conditions. Some of them know only the kind of machine they use in their lab.

Browse this forum. Read "Our Collective Wisdom" - we have thousands and thousands of hours of successful sleep therapy under out belts.

You may have either an automatic (self adjusting) machine, with the minimum set too low, or a ramp, which starts too low, or takes too long.

The following, from ww is not necessarily true for all machines and all people

If you have a titrated value from your sleep study, learn how to set your machine pressure and set the bottom end at the titrated value and the top value about 4 cm above that.

Some of us have discovered straight pressure is simply better for them.
Some of us have discovered a very narrow range is good for them.

On my machine, the Puritan Bennett 420E you can set in initial pressure at the the titrated pressure, and minimum pressure slightly lower than that, and the machine will go up to the initial very quickly.

Self adjusting machines have different algorithms - and for some of us, one algorithm is much better than the other.

Welcome, and good luck!
O.

[NightHawkeye]

Occasionally when falling to sleep I find myself waking up with a deep breath (sometimes followed by fast breathing). I believe this to be an awakening caused by my windpipe collapsing right after the start of sleep.

This seems to be fairly common and has been discussed here a few times. As I recall, both obstructive and central apneas are likely when falling asleep. (The centrals in this instance are apparently benign, btw.)

While I have an auto bipap which will presumably eventually raise the pressure if it starts out too low, it occurs to me that it might pay to have the pressure high enough so that no adjustments normally occur while sleep. This would eliminate the apneas that occur while the machine is adjusting the pressure. What are the advantages and disadvantages to this?

Advantages: Great, if it happens to work for you. That's how regular BiPAP and CPAP work.

Disadvantages: Why are you using an auto-BiPAP? Too high a pressure for comfort? Aerophagia? The common reasons which drive folks to use autos are the disadvantages.

What I have been look for is a “manual” on how to pick the pressure. I have not found this although I assume it must exist in training materials for sleep lab technicians or in the medical literature. Does anyone have a reference to such a document?

Professor, please let us know if you find such a document. Judging from frequent reports here, medical practitioners within the sleep industry most commonly practice benign ignorance on such practical matters of OSA therapy. Despite the pretentious (as well as delusional and self-serving) claims made by the medical professionals, many of the practical aspects of successful therapy have been hard-won on an individual basis, not by the over-seers within the medical community, but by those who benefit from successful therapy. Those lessons are then subsequently passed on by word-of-mouth from one user to another.

Regards,
Bill

[ProfessorEd]

My machine is the Respionics M series whcih is fully data capable and I have gotten the software (thanks to a member here).

The issue remains of what rules to use in setting pressures, minimum and maximun. This machine apparently does not provide for setting a starting pressure (but apparently starts at the minimum). If I could set the starting pressure (as my Puritan -bennett auto permits), I would be inclined to start at the desired pressure (or guess at it) and then let the machine low it if need be.

Since it apparenlty starts at the minimum (I don't use the ramp), I assume the minimum should be set high enough so there are seldom apneas (I am currently using 12). I have been wondering if making it higher (would should reduce the apena rate more) would be wise, or if there are any disadvantages.

[Hawthorne]

ProfessorEd - you said you had a fully data capable M Series but is it a PRO or an AUTO? I'm trying to figure out if you are wanting to set a range or a set pressure and I am confused because both of these machines are fully data capable.

[Pineapple]

Or is it the ramp start?

[NightHawkeye]

The issue remains of what rules to use in setting pressures, minimum and maximun.

I understand, now. Here's something I posted earlier today which hopefully can provide a little insight for you. It was written a couple of years ago by an esteemed member of the sleep profession.

From: http://www.apneasupport.org/about731.html

Hi Guys!
Actually, I do believe that it is the other way around, you have to fix the apneas with the EPAP, or baseline pressure, first. If the airway is not open, then increasing the IPAP would not help address an apnea, because the machine could not sense an inspiratory effort and respond. But as long as there is any kind of flow, as you see in a hypopnea, then you can blast through it with the IPAP.
Haku, while the explanation offered by your physician that obstruction does not occur during exhalation is basically correct (this is what allows C-Flex to work), proper EPAP setting is critical in OSA treatment. If the EPAP setting does not completely eliminate apneas (not necessarily hypopneas, RERAs, snores, etc.) BiPAP simply will not work. It will simply sit there waiting for an effort that it cannot see.
So in your case, if your ideal CPAP was 14 cmH20, you could only use BiPAP of 14/7 if all your apneas were gone at 7. If it took 14 cmH2O to get rid of all your apneas, then your BiPAP would have to be at least 16/14. Since you had mostly hypopneas, chances are that your EPAP setting is functional. The point is, though, EPAP selection is not arbitrary, it's based on the point where apneas are eliminated, or at least turned into hypopneas.
sleepydave

I'll also add that I personally found that the auto algorithm in the Respironics BiPAP-auto (original, non-M) did not work well for me. Instead, I resorted to using the machine it in standard BiPAP mode.

The excerpt above is certainly not the "manual" you were looking for, but perhaps it gives you some insight into how sleep techs go about adjusting IPAP and EPAP.

Regards,
Bill

[ozij]

While I have an auto bipap which will presumably eventually raise the pressure if it starts out too low, it occurs to me that it might pay to have the pressure high enough so that no adjustments normally occur while sleep. This would eliminate the apneas that occur while the machine is adjusting the pressure.

There are two reasons to use an Auto. Not using higher pressure when it isn't needed, and having, so to speak, a "reserve" of high pressure for when it is needed.

The PB420E handles this by having you enter your recommended pressure as the initial, and a minimum as the point to which pressure can drop down safely.

The Respironics auto algorithm is different. The machine constantly - like about every 6-10 minutes - challenges, the limits, moving slightly up or down to see if therapy can be optimized.

If you want to use your Respironics auto for comfort, it would make sense for you to set the minimum at slightly less than your recommended pressure.

If you want to use your Respironicse auto for those times when you need more than the usual pressure - e.g. REM sleep, or different postions - open up the top of the range.

For some of us - and opened up top is fine. For others, it causes sleep disrutptions, pressure induced apneas, etc. Nobody can tell ahead of time how it would be in your case - you can't do yourself longterm harm by trying. Only cause yourself a restless night, and some aerophagia (too much pressure is no way like to much insulin.... and while you can't get back the hours you lose, the effect are otherwise reversible - and you can bring the pressure down in the middle of the nigth if you need to). If your PB showed no apneas /ca - go ahead and let your Respironics have its head. If you did have apnea /ca above certain pressure, limit the Respironics.

Another reason to consider limiting the top of the range is snores: if you snore, the machine raises pressure aggressively - and may do so to a very high pressure. This can be handled (on both PB and Respironics) by making sure the min. is above your snore level.

As for the ramp: Only set it as low as is absolutely necessary for you to fall asleep with. The ramp - epecially if it's very low - may cause a vicious cycle of "almost falling asleep, being jerked awake by an apnea/hypopnea, hitting ramp, almost falling asleep....etc.".

Hope this helps.
O.

[Snoredog]

What disadvantages are there to a higher pressure than the minimum needed to lower the apnea/hyena level to below, say 5.

Occasionally when falling to sleep I find myself waking up with a deep breath (sometimes followed by fast breathing). I believe this to be an awakening caused by my windpipe collapsing right after the start of sleep. While I have an auto bipap which will presumably eventually raise the pressure if it starts out too low, it occurs to me that it might pay to have the pressure high enough so that no adjustments normally occur while sleep. This would eliminate the apneas that occur while the machine is adjusting the pressure. What are the advantages and disadvantages to this?

An obvious disadvantage is more discomfort and greater risk of mouth leakage.

The only medical argument I have seen is a reference to adverse effects from high oxygen partial pressures. While these studies were presumably done with normal pressures and oxygen enrichment, raising the pressure does raise the oxygen partial pressure also, although I suspect this would be a small effect in the ranges being discussed (say from 10 to 12).

What I have been look for is a “manual” on how to pick the pressure. I have not found this although I assume it must exist in training materials for sleep lab technicians or in the medical literature. Does anyone have a reference to such a document?

The sequence of events you describe above are Sleep Onset events or those that occur in the first 20 minutes or so of reaching sleep. IF the machine "responds" to those events then it can sometimes make them worse. Some machines have a "settling" period after starting the session to get past those. Your particular machine may even confuse those onset events as obstructive where they are generally central or very shallow breathing.

Believe you indicated you have a M series machine? If so it should have Auto:Ramp, you could use that Ramp as a "settling" feature by setting the Ramp pressure the same as Minimum pressure and for 30 minutes. Then when you put on the mask you would hit Ramp button, it would delay normal response until the timer expires. However if events are seen during that period it may accelerate to therapy pressure.

you should be able to confirm these with the Encore reports, you would see those events at the start of the session (first 30 minutes of said session).

If Bipap, I would look at your reports and note the pressure at any apnea, understand that IPAP and EPAP address SDB events differently as SAG suggested in Bill's quote above.

IF you observe your Bipap Auto Daily report and refer to the legend at the bottom of the page it will list out IPAP and EPAP seperately. You will see that Apnea is only addressed with EPAP as SAG suggests, and Hypopnea is addressed with IPAP pressure. Vibratory snore would be addressed with both pressures.

So when you are trying to eliminate an event WHICH pressure should you change?

- Alway address "Apnea" first. Apnea is addressed EPAP pressure. If you squeeze down a Apnea, it turns into a Hypopnea, if you squeeze down a Hypopnea it turns into a Flow Limitation, but you can also have those events by themselves and spontaneously.

- After Apnea is addressed with EPAP, then its time to address Hypopnea. Hypopnea is addressed with IPAP, so if HI remains higher than liked then you increase IPAP (leaving EPAP alone) until HI drops to acceptable levels or <5.

You can bump up both pressures a bit if VS persists, EPAP is the big hammer of the two. EPAP can be more compared to CPAP pressure than IPAP.

So if you follow the above concept and the pressure "rules" imposed by that machine, then you can comfortably address any event seen using the correct pressure. Again, your Encore reports show you which pressure addresses which event.

[Hawthorne]

Oiji - I set my M Series minimum just below my recommended pressure. I have a little "reserve" of higher pressure for when I may need it. Actually, that was YOUR suggestion to me and it has worked extremely well, for me. I have not opened up the maximum pressure at all. It's just high enough for a little reserve and I very rarely get to that maximum setting and then, for only a short time during a night. As you said, it's there when I need it! I have not set the ramp in the auto setting. When I had the minimum setting 1 1/2 cm lower than I currently have it, I had to struggle some to inhale. Not so at this minimum - close to my recommended pressure. Given this situation, I thought ramp would not be beneficial for me.
My numbers, in the morning, are great. I know that things may change and these pressures may have to be adjusted as time goes on but I have had it set at the current range for just about 6 weeks and it has been very successful for my current situation. For me, your suggestion works well with the M Series. Any changes I may need to make in the future will be based on this same premise. If I use this premise for future changes, I will probably need to assess, again, whether it is still valid--for me.