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Which comes first? leak or higher pressure?
#1
This may be a dumb question, but when i review my data i often see huge leaks associated with very high pressure. So which comes first? Does the leak trigger the machine to increase pressure? One would assume the cpap machine is responding to a breathing event.

BUT, most of the time i have no event that coincides with the leak/pressure spike.

I am experimenting with lowering the upper limit on my autoset and my leaks are greatly improved.

It seems that if the machine is responding with increase pressure during a leak, the leak will only be made worse. Maybe i don't fully understand how the technology is working.
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#2
Someone else responded in another thread that CPAP machines never respond to leaks with higher pressure, they respond with higher flow rate to maintain the large pressure.

However, it is possible that a machine is increasing the pressure for some other reason and that increase results in a leak, the machine would continue to increase flow and pressure until the target pressure it was heading for when the leak occurred - most likely?

I am not a Medical professional and I don't play one on the internet.
Started CPAP Therapy April 5, 2016
I'd Rather Be Sleeping
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#3
(03-29-2016, 09:38 AM)drgrimes Wrote: This may be a dumb question, but when i review my data i often see huge leaks associated with very high pressure. So which comes first? Does the leak trigger the machine to increase pressure?


It might (see below) but more likely the leak is caused by the increased pressure.

Quote:One would assume the cpap machine is responding to a breathing event.

BUT, most of the time i have no event that coincides with the leak/pressure spike.

It's not necessarily an event, it could be, and more likely is, flow limitation. Look at the flow limitation graph and see if spikes precede pressure increases. When the shape of your flow rate graph changes in certain ways, it's a sign that an event is about to occur. Flow limitation is a measure of these changes, and it indicates that the pressure should be raised to prevent the upcoming event.
Sleepster
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#4
(03-29-2016, 01:21 PM)Sleepster Wrote:
(03-29-2016, 09:38 AM)drgrimes Wrote: This may be a dumb question, but when i review my data i often see huge leaks associated with very high pressure. So which comes first? Does the leak trigger the machine to increase pressure?


It might (see below) but more likely the leak is caused by the increased pressure.

Quote:One would assume the cpap machine is responding to a breathing event.

BUT, most of the time i have no event that coincides with the leak/pressure spike.

It's not necessarily an event, it could be, and more likely is, flow limitation. Look at the flow limitation graph and see if spikes precede pressure increases.

Or snores. Also look at the snore graph and see if any spikes in the snore graph precede the pressure increase.

The Resmed machines respond rather aggressively to both flow limitations and snores.

Questions about SleepyHead?
See my Guide to SleepyHead
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#5
(03-29-2016, 09:38 AM)drgrimes Wrote: This may be a dumb question, but when i review my data i often see huge leaks associated with very high pressure. So which comes first? Does the leak trigger the machine to increase pressure? One would assume the cpap machine is responding to a breathing event.

BUT, most of the time i have no event that coincides with the leak/pressure spike.

I am experimenting with lowering the upper limit on my autoset and my leaks are greatly improved.

It seems that if the machine is responding with increase pressure during a leak, the leak will only be made worse. Maybe i don't fully understand how the technology is working.

*sees profile picture whilst reading thread..*

I'm sorry for going off topic, but I really would love to have a steampunk style mask.

*backs out of room*
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#6
(03-29-2016, 08:03 PM)PappinLikeABoss Wrote:
(03-29-2016, 09:38 AM)drgrimes Wrote: This may be a dumb question, but when i review my data i often see huge leaks associated with very high pressure. So which comes first? Does the leak trigger the machine to increase pressure? One would assume the cpap machine is responding to a breathing event.

BUT, most of the time i have no event that coincides with the leak/pressure spike.

I am experimenting with lowering the upper limit on my autoset and my leaks are greatly improved.

It seems that if the machine is responding with increase pressure during a leak, the leak will only be made worse. Maybe i don't fully understand how the technology is working.

*sees profile picture whilst reading thread..*

I'm sorry for going off topic, but I really would love to have a steampunk style mask.

*backs out of room*

Sounds like a product idea Smile

I am not a Medical professional and I don't play one on the internet.
Started CPAP Therapy April 5, 2016
I'd Rather Be Sleeping
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#7
(03-29-2016, 03:40 PM)robysue Wrote:
(03-29-2016, 01:21 PM)Sleepster Wrote:
(03-29-2016, 09:38 AM)drgrimes Wrote: This may be a dumb question, but when i review my data i often see huge leaks associated with very high pressure. So which comes first? Does the leak trigger the machine to increase pressure?


It might (see below) but more likely the leak is caused by the increased pressure.

Quote:One would assume the cpap machine is responding to a breathing event.

BUT, most of the time i have no event that coincides with the leak/pressure spike.

It's not necessarily an event, it could be, and more likely is, flow limitation. Look at the flow limitation graph and see if spikes precede pressure increases.

Or snores. Also look at the snore graph and see if any spikes in the snore graph precede the pressure increase.

The Resmed machines respond rather aggressively to both flow limitations and snores.

My S9 VPAP auto does react to both flow limitations and snores but it reacts much more aggressively to flow limitations than snores. Just thought someone might be interested.

Best Regards,

PaytonA
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#8
(03-29-2016, 09:38 AM)drgrimes Wrote: This may be a dumb question, but when i review my data i often see huge leaks associated with very high pressure. So which comes first? Does the leak trigger the machine to increase pressure? One would assume the cpap machine is responding to a breathing event.

BUT, most of the time i have no event that coincides with the leak/pressure spike.

I am experimenting with lowering the upper limit on my autoset and my leaks are greatly improved.

It seems that if the machine is responding with increase pressure during a leak, the leak will only be made worse. Maybe i don't fully understand how the technology is working.

I am going to regurgitate something that I said in another thread with respect to my opinion regarding leaks and pressure.

Quote:Frankly, I take a very simplistic view of leaks and pressure. The pressure is there to treat your Obstructive Apnea. Assuming that you have found the best pressure/range where you are being well treated. Why would one want to interfere with one's treatment by reducing the pressure to reduce leaks. Fix the leak so that it does not occur at your therapeutic pressure whether it is the set pressure or a machine generated one within the set limits.

in the case where no mask can be found that seals at your therapeutic pressures then maybe one must find a middle road that gives the best overall results.

Turning the pressure down in response to leaks is a very common (I believe) reaction. It was my first reaction when starting out. I received some advice from some smart people and never did it and I did manage to reduce my leaks eventually without reducing the pressure after i found this forum and started learning more.

Best Regards,

PaytonA
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#9
Payton i agree with the principle that the pressure is to treat the obstructive apnea, and thus reduce the number of breathing events or AHI. And so when i reduced the max pressure i expected to see a rise in AHI, but it actually improved a bit, but the more noticeable thing was the huge reduction in leak. I think this particular mask must have some limitations in this regard.

Initially i tried everything to get the leaks under control. I think maybe once the skirt of the Dreamwear blows out, the only way to seal it again is to turn everything off and start over. If this happens several times per night it defeats its purpose. I have tried every combination of fitting, and strap adjusting but the problem persisted. I really wanted to figure out a way to make this mask work because i wanted the hose off the front of my face. I tried this mask once before and failed.

I don't advocate anyone monkeying with their settings although i wanted to see if i could get this mask to quit blowing out. Had I seen worsening AHI, i would have immediately change the setting back. Right now after several nights in a row, i am seeing significantly better results with both leakage and AHI. Not one time has it awakened me and required starting over.
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#10
Great job. I am happy that you are getting good results. My message is actually for the benefit of newbies that might read this thread.

Best Regards,

PaytonA
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