Goal of APAP vs. CPAP

[Kemosabe2]

With an APAP machine, is the goal to have no AHI's? I've been having more, not less since I switched from CPAP. It was my understanding that the APAP machine would automatically give me the correct amount of pressure at all times and I'd therefore have little to no events. Am I wrong?

[Wulfman]

With an APAP machine, is the goal to have no AHI's? I've been having more, not less since I switched from CPAP. It was my understanding that the APAP machine would automatically give me the correct amount of pressure at all times and I'd therefore have little to no events. Am I wrong?

Yep......you're wrong.

APAPs need "events" to trigger pressure increases......snores, flow limitations, hypopneas and apneas.
If you're sitting at a lower pressure and you have an event that takes a much higher pressure to clear that event, the machine is going to take too long to get there......so the events will occur before the pressure gets to where it needs to be. It doesn't know what pressure it's going to need until it gets there.
If you need a pressure higher then 10 cm. with that ResMed machine, it may not go past 10 unless there are snores or flow limitations that precede the event. You should set your minimum pressure high enough to take care of almost all of your events. If you're using EPR, you need to set your minimum pressure even higher because when you exhale with EPR, it drops your "effective" pressure by the number of your EPR setting 1, 2 or 3 cm.

Many people who get APAPs don't understand how they work and are frequently disappointed by their results for that reason.


Den

[Kemosabe2]

Den, Thank you so much. I've had a hard time understanding why my AHI with the CPAP is suddenly more than double. Obviously I thought and hoped it would be much lower. With the APAP I'm waking up coughing from what seems like a sudden burst of air being pushed down my throat. My CPAP pressure was 8.2 and I've noticed that the APAP is sometimes over 15, which is almost double the pressure. I have a hard time believeing I actually need all that pressure because it really doesn't feel good when I get it (even makes my ears ache!) I don't know if something's wrong with the machine or if my breathing is really that screwed up! At least now I have a better understanding of how it works. thanks

[Wulfman]

Den, Thank you so much. I've had a hard time understanding why my AHI with the CPAP is suddenly more than double. Obviously I thought and hoped it would be much lower. With the APAP I'm waking up coughing from what seems like a sudden burst of air being pushed down my throat. My CPAP pressure was 8.2 and I've noticed that the APAP is sometimes over 15, which is almost double the pressure. I have a hard time believeing I actually need all that pressure because it really doesn't feel good when I get it (even makes my ears ache!) I don't know if something's wrong with the machine or if my breathing is really that screwed up! At least now I have a better understanding of how it works. thanks

What are your pressure settings?
The ResMeds CAN be quite aggressive with pressure increases under certain circumstances. Leaks can also exacerbate that, too.
Are you getting your data from the LCD or do you have the software?

In the times I've tried APAP mode, I've also had higher AHIs and the pressure changes have disturbed my sleep.


Den

[Kemosabe2]

Originally the settings for the APAP were 4-20. I changed it today to 6-12 because I read somewhere on this site that there should be a pressure difference of 6 and I know over 15 didn't feel good at all. This new APAP machine (only 3 days) is waking me more than letting me sleep (noisy, excess pressure makes me cough and burp almost constantly) & I've wondered if all the coughing or burping could be making the machine think it needs to increase pressure and it's creating a vicious circle?

I get my info. from the LCD. I don't know any other way.

[Kemosabe2]

Den, Also, the APAP doesn't have EPR and I have found it difficult to breathe out against the higher pressures.

[Wulfman]

Den, Also, the APAP doesn't have EPR and I have found it difficult to breathe out against the higher pressures.

OK. You do have the older Vantage. It does have EPR available in CPAP mode.

Sounds like you're getting "aerophagia" at some point. If you insist on running that thing in APAP mode, I'd suggest setting your minimum pressure at around 8 (where your CPAP pressure was) and set the maximum to 10 or 11 and see what happens. If you're still having those adverse effects, further experimentation may be in order.
Do you take a blood pressure medication? (like Lisinopril......which is frequently prescribed for diabetics)
One of its side effects is coughing.

http://www.drugs.com/lisinopril.html


Den

[Kemosabe2]

I don't have high blood pressure. I didn't have coughing with the CPAP and noticed it with the higher pressure. The reason I'm using the APA is because I've gained 40 pounds since my titration and I don't want to have to go in for a new overnight study and thought I could figure out the best pressure for me doing it this way. I'm wrong again?! I know the 8.2 isn't getting the job done anymore and really want to feel better again. Do you suggest I just go back to the CPAP and call for a new titration? Would that be best? I can't tell you how much I appreciate you're helping me with this. Lisa

[Wulfman]

I would hold off on another titration for the time being. You've barely scratched the surface with experimenting with other settings. It's been my observation from 4 1/2 years on this forum that there is a small minority of patients that do better with a range of pressures......whereas, most do better by finding the right single pressure (for the reasons you're discovering).

Many people have had problems with aerophagia and there are no hard and fast rules for avoiding it......each person has had to experiment to find a pressure that's high enough to be effective and low enough to avoid the bloating, gas and "whatever". Some do better with straight pressure, some do better with exhale relief (EPR or C-Flex), some with APAP and some have had to go to bi-level therapy.

My suggestion would be to work up from 8 or 9 (in CPAP mode) and see how it goes. That way, you could also try EPR. Just remember, that if you have your CPAP pressure at 9 and EPR at a setting of 1, then your exhale pressure will be 8. In bi-level therapy, it's the exhale pressure that needs to be set to where it prevents as many apneas as possible......and the ResMed EPR makes the S8 act like a mini bi-level machine......because it actually drops the pressure by the number of centimeters of pressure of the EPR setting. A Respironics machine with C-Flex, on the other hand, drops the pressure slightly at the onset of exhaling and then keeps a slight amount of pressure there to try to prevent apneas. With C-Flex, the pressure drop is "relative" to the person's exhale effort.

Den

[Kemosabe2]

Thank you very much, Den. I'm going to put it on CPAP mode and go to a pressure of 9 with EPR set to 3, which is where it was before. I believe the higher the EPR, the easier it is to exhale. Obviously, I could be wrong on that too! Either way, that's what I'm going to do for tonight and see what happens. I definitely need to get a decent nights sleep.

Thanks again & sleep tight!
Lisa

[Wulfman]

Thank you very much, Den. I'm going to put it on CPAP mode and go to a pressure of 9 with EPR set to 3, which is where it was before. I believe the higher the EPR, the easier it is to exhale. Obviously, I could be wrong on that too! Either way, that's what I'm going to do for tonight and see what happens. I definitely need to get a decent nights sleep.

Thanks again & sleep tight!
Lisa

Just remember that those settings will give you an effective exhale pressure of "6". But, yes, the higher the EPR setting, the more pressure drop on exhale (or more pressure/exhale relief).


Den