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General Discussion on any topic relating to CPAP and/or Sleep Apnea.
orangegrower
 
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Why are there minimum and maximum setting on an APAP

Postby orangegrower on Sun Mar 03, 2013 4:50 pm

If an Auto machine (APAP) adjusts the pressure automatically why does it need a minimum and maximum pressure setting? Why not leave the machine adjust to the proper pressure. Mine is set at 7 and 11. I rarely go above 9 and spend 80 to 90% of the time running on my minimum setting which is 7.

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BlackSpinner
 
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Re: Why are there minimum and maximum setting on an APAP

Postby BlackSpinner on Sun Mar 03, 2013 4:52 pm

Because it takes time for it to get to the needed pressure. If it is set wide open 4-20 and you have apneas that need a pressure of 12 or higher it will not always get there in time to stop them quickly.

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khauser
 
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Re: Why are there minimum and maximum setting on an APAP

Postby khauser on Sun Mar 03, 2013 4:59 pm

Also because some people have central apneas as the pressure goes up, do unless you or the doctor is monitoring results, wide open can be worse.

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StuUnderPressure
 
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Re: Why are there minimum and maximum setting on an APAP

Postby StuUnderPressure on Sun Mar 03, 2013 5:07 pm

orangegrower wrote:Mine is set at 7 and 11. I rarely go above 9 and spend 80 to 90% of the time running on my minimum setting which is 7.


Shouldn't you consider lowering the minimum if you spend that much time at the minimum.

If you do decide to lower it, do it in .5 increments & leave it there for at least a week to see what effect it has.

Then, if you feel the need to lower it even further, you can lower it another .5 & leave it there for another week.

Do this until you find a minimum that you won't spend 80 to 90% of the time at.

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khauser
 
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Re: Why are there minimum and maximum setting on an APAP

Postby khauser on Sun Mar 03, 2013 5:14 pm

StuUnderPressure wrote:Shouldn't you consider lowering the minimum if you spend that much time at the minimum.

Not necessarily ... if on a lower pressure one gets more adverse events it might be better to peg the minimum higher. That's three case with me...

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StuUnderPressure
 
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Re: Why are there minimum and maximum setting on an APAP

Postby StuUnderPressure on Sun Mar 03, 2013 5:24 pm

khauser wrote:
StuUnderPressure wrote:Shouldn't you consider lowering the minimum if you spend that much time at the minimum.

Not necessarily ... if on a lower pressure one gets more adverse events it might be better to peg the minimum higher. That's three case with me...


But he did not say he was having any "adverse events"

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archangle
 
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Re: Why are there minimum and maximum setting on an APAP

Postby archangle on Sun Mar 03, 2013 6:04 pm

Maxiumum: Sometimes the machine will never find a pressure that it "likes" and may keep increasing the pressure without improving the results.

Minimum: It can be uncomfortable at the lower settings. Many people feel they're suffocating at low pressure. You may have some apneas before it adjusts upwards. Both at the beginning of the night, and as you change sleep stages. You may, for instance, only have apnea when you are in REM sleep and the pressure will drop between REM periods.

A too low minimum pressure can really hurt compliance because it can increase the panic and claustrophobia for new users.

Range: A wide range can also cause problems. If you fit your mask at 4 cm, and then your pressure goes up to 12 at night, you may develop a leak as the pressure goes up. It's easier to get the right fit if you start at something like the right pressure. The pressure variations also bother some people, so it's better to start with something like 10-14 than to set it at 4-20 and find it ends up running between 4 and 12 during the night.

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Re: Why are there minimum and maximum setting on an APAP

Postby Wulfman... on Sun Mar 03, 2013 6:24 pm

orangegrower wrote:If an Auto machine (APAP) adjusts the pressure automatically why does it need a minimum and maximum pressure setting? Why not leave the machine adjust to the proper pressure. Mine is set at 7 and 11. I rarely go above 9 and spend 80 to 90% of the time running on my minimum setting which is 7.


Because, it does NOT adjust "automatically" and it doesn't magically "know" what pressure you need.
Unfortunately, too many people think that they do.
The APAPs respond to breathing changes, events and anomalies by means of sensors and internal programs (algorithms)......which may or may not be correct.
If the minimum and maximum settings are not set to "optimum" starting and limiting pressures, the user can be in for a miserable experience and less-than-adequate therapy.


Den

.

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idamtnboy
 
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Re: Why are there minimum and maximum setting on an APAP

Postby idamtnboy on Sun Mar 03, 2013 8:18 pm

orangegrower wrote:If an Auto machine (APAP) adjusts the pressure automatically why does it need a minimum and maximum pressure setting? Why not leave the machine adjust to the proper pressure. Mine is set at 7 and 11. I rarely go above 9 and spend 80 to 90% of the time running on my minimum setting which is 7.

I started a discussion nearly a year ago about the cardiac impacts of APAP vs CPAP. http://www.cpaptalk.com/viewtopic.php?f=1&t=76278&st=0&sk=t&sd=a&hilit=apap+vs+cpap
There really is no solid evidence that APAP is not as good for you in the long term, but some of the discussion is interesting.

Here is a later article http://www.systematicreviewsjournal.com/content/1/1/20

The conclusion is interesting.

Conclusions

APAP and CPAP were similar in affecting relatively short-term changes in AHI, quality of life, and most other sleep study measures in the treatment of patients with moderate to severe OSA but without significant comorbidities. APAP, however, did reduce sleepiness by approximately 0.5 ESS points more than fixed CPAP. Patients who received APAP also had objectively measured compliance of 11 minutes per night more than those who received fixed CPAP. We surmise that the clinical significance of these reported improvements in ESS and compliance is marginal at best. It is doubtful that additional short-term trials comparing APAP and CPAP to examine these measures will substantially alter these results. However, longer-term and larger trials that evaluate clinical outcomes, such as cardiovascular events, and directly estimate differential effects in different sub-populations may be of value. Furthermore, the current trial evidence is limited to patients newly diagnosed with sleep apnea or who are otherwise naïve to CPAP; thus, future trials of patients who had previously used CPAP may be of value. For now, based on the available data from experimental studies on short-term effects only, the decision to use APAP versus CPAP may well depend on individual patient preferences, specific reasons for non-compliance, costs and other practical considerations that clinicians and patients will need to assess on an individual basis.

So, at this point it looks like the advice is, combining the experts opinions and we users' opinions, use whichever method you like better and works the best for you, and in either case tweak the settings for the best overall end result.

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growing
 
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Re: Why are there minimum and maximum setting on an APAP

Postby growing on Sun Mar 03, 2013 9:50 pm

archangle wrote:Maxiumum: Sometimes the machine will never find a pressure that it "likes" and may keep increasing the pressure without improving the results.

Minimum: It can be uncomfortable at the lower settings. Many people feel they're suffocating at low pressure. You may have some apneas before it adjusts upwards. Both at the beginning of the night, and as you change sleep stages. You may, for instance, only have apnea when you are in REM sleep and the pressure will drop between REM periods.

A too low minimum pressure can really hurt compliance because it can increase the panic and claustrophobia for new users.

Range: A wide range can also cause problems. If you fit your mask at 4 cm, and then your pressure goes up to 12 at night, you may develop a leak as the pressure goes up. It's easier to get the right fit if you start at something like the right pressure. The pressure variations also bother some people, so it's better to start with something like 10-14 than to set it at 4-20 and find it ends up running between 4 and 12 during the night.


This subject prompts me to inform that my machine seems to be all set to make a record. :lol: It does not nudge from the minimum whatever be the range. The APAP works like a CPAP.

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archangle
 
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Re: Why are there minimum and maximum setting on an APAP

Postby archangle on Mon Mar 04, 2013 4:26 am

growing wrote:This subject prompts me to inform that my machine seems to be all set to make a record. :lol: It does not nudge from the minimum whatever be the range. The APAP works like a CPAP.


Well, the machine tries to find the lowest pressure that will fix your apnea. If 7 cures you, be happy.

You might even be able to get by with a lower minimum pressure.

However, I find I feel better if I set my minimum pressure a bit higher than the machine wants to go, and a little bit higher than where my AHI goes essentially to zero.

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growing
 
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Re: Why are there minimum and maximum setting on an APAP

Postby growing on Mon Mar 04, 2013 5:23 am

archangle wrote:
growing wrote:This subject prompts me to inform that my machine seems to be all set to make a record. :lol: It does not nudge from the minimum whatever be the range. The APAP works like a CPAP.


Well, the machine tries to find the lowest pressure that will fix your apnea. If 7 cures you, be happy.

You might even be able to get by with a lower minimum pressure.

However, I find I feel better if I set my minimum pressure a bit higher than the machine wants to go, and a little bit higher than where my AHI goes essentially to zero.


My therapy pressure graph has remained a perfect straight line whether the range was at 3-15, 4-15, 5-15 or 6-15 cm. Only time it has shown a bit of excursion was when the minimum was at 7.0 cm but with distinctly higher AHI numbers.

We know Devilbiss algorithm depends on snore as the precursor and I do not snore on the machine. However, my confusion is

1) on the similar behavior of different pressure ranges from 3-15 to 6-15 cm; and
2) the increase of AHI numbers (obstructive, mainly) from the minimum of 7.0 cm onwards despite the tendency of slight deviation in the therapy pressure line.

Thanks for the comment.

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archangle
 
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Re: Why are there minimum and maximum setting on an APAP

Postby archangle on Mon Mar 04, 2013 5:32 am

growing wrote:
archangle wrote:My therapy pressure graph has remained a perfect straight line whether the range was at 3-15, 4-15, 5-15 or 6-15 cm. Only time it has shown a bit of excursion was when the minimum was at 7.0 cm but with distinctly higher AHI numbers.

We know Devilbiss algorithm depends on snore as the precursor and I do not snore on the machine. However, my confusion is

1) on the similar behavior of different pressure ranges from 3-15 to 6-15 cm; and
2) the increase of AHI numbers (obstructive, mainly) from the minimum of 7.0 cm onwards despite the tendency of slight deviation in the therapy pressure line.

Thanks for the comment.


What's your AHI at 3 cmH2O? Maybe you don't really need CPAP. Or 3 is enough to cure you.

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Additional Comments: Also SleepyHead, PRS1 Auto, Respironics Auto M series, Legacy Auto, and Legacy Plus
Please enter your equipment in your profile so we can help you.
Click here for information on the most common alternative to CPAP.
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growing
 
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Re: Why are there minimum and maximum setting on an APAP

Postby growing on Mon Mar 04, 2013 10:49 am

archangle wrote:
growing wrote:
archangle wrote:My therapy pressure graph has remained a perfect straight line whether the range was at 3-15, 4-15, 5-15 or 6-15 cm. Only time it has shown a bit of excursion was when the minimum was at 7.0 cm but with distinctly higher AHI numbers.

We know Devilbiss algorithm depends on snore as the precursor and I do not snore on the machine. However, my confusion is

1) on the similar behavior of different pressure ranges from 3-15 to 6-15 cm; and
2) the increase of AHI numbers (obstructive, mainly) from the minimum of 7.0 cm onwards despite the tendency of slight deviation in the therapy pressure line.

Thanks for the comment.


What's your AHI at 3 cmH2O? Maybe you don't really need CPAP. Or 3 is enough to cure you.


AHI at 3-15 cm were 1.24, 1.08, 1.36 and 0.93 on Dec 21 to 24, 2013.

About 2 months back, I had been to a place where there was no electricity, whole night. I was compelled to sleep with just a BreathRight strip. It was a horrible night worse than the days when I did not have a CPAP machine. Bottom-line: I should use the machine.

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