Sleep Doctor Refuses to Allow APAP

slept wrote:I spoke with the doctor and he flatly refused to prescribe an APAP. He said that the technology was unproven, and that patients had to suffer apnea events before the machine would respond with additional pressure.

He's just plain wrong. On both counts.

First, many studies have evaluated the technology of autos and proven their accuracy and effectiveness.

Secondly, an auto does NOT only respond to apnea events. It also prevents them. This is from the definition of an APAP (in CPAPopedia):

An AutoPAP differs from a CPAP in that an AutoPAP uses algorithms to sense subtle changes in the user's breathing and deliver only the amount of pressure necessary to keep the airway open.

An AutoPAP automatically varies the pressure to prevent and/or correct sleep disordered breathing events - apneas, hypopneas, air flow restrictions, and snores.

It is evident your doc doesn't know the facts regarding APAPs and it appears he'd rather give you faulty data than admit he is uninformed. Run! Run away!!!!

I am really starting to wonder about these "certified" pulmonary sleep docs!

My sleep doc is also strongly for JUST prescribing straight CPAP at a single pressure. I take his prescription to the DME and managed to get an autoPAP.

My doc's rationale was to set my straight CPAP pressure at 9cm.

I notice with my very responsive 420E that I spend 90% of most nights at 6cm, and occasionaly have it spike to 10cm for very short periods.

Sooooo.....if I took the docs advice, I would be running at a single pressure that was too high 90% of the time and too low the other 9% and just right 1% of the time, combined with much worse areophagia and other discomfort from the higher pressure.

WTF!!!???

This is the best a trained professional can do? I can certainly learn more and probably get less erroneous information on this forum of "amateurs".

I would switch to another DME, but this guy is nearby and I can usually browbeat him into prescribing what I need, probably because he knows I would switch if he gave me too much flak. So yes indeed, follow all the good advice in the previous posts and let your doc know that he needs to get with the program or you WILL leave and take ALL those overinflated charges with you and give them to someone else.

Everything is negotiable.

Roger... wrote: Hypopneas are another area where the machine gets confused and of course the Auto feature goes to sleep if the mask is showing a maximum leak value. Even short period leaks will cause the machine to drop to the lowest setting and stay there for a while, so when you think about APAP, don’t think it makes exhalation easier, although working at a lower pressure helps, think that you’ll need to have the machine’s working range set near to where your obstructions are handled properly. This is where the APAP will shine.

Maximum leaks are the biggest weakness my Auto seems to have. Last night I began the process of trying to use a full face RESMed Ultra and was surprised to see the data card show that I spent 86% of the night in a large leak state that made the machine stop recording events that happened during that period. As a result of the leak, the machine ran at the bottom setting of 12CM for most of the night and I didn’t even know I had a maximum leak during that period.

I am curious about what you are saying. If I understand you correctly, you are saying that when you have a large leak your machine runs at a low pressure.

My experience has been the opposite. When my mask is leaking my machine goes all out to try and create more pressure. It shoots up to the top limit pressure setting and this tends to be quite unpleasant.

Hello David,
I should have put more explanation into the paragraph, but the fundamental logic reflects how my REMStar Auto w/CFLEX operates. To explain it better I’ve created a snapshot of last night’s report that shows when there is a large leak, the machine stays at its lowest set value. In my case, the low side setting is 12cm and the high side range is 14cm.

Click on this image link so the image will appear on a new page:
Large Leak Problem Example

Last night’s report is shorter than usual because I’m struggling with congestion from a cold or some other crud so the early part of the night isn’t reflected because I turned it off for a couple of hours. In the earlier section the information is about the same, but it is only for about 2.5 hours.

In the image above, you’ll see that when the REMStar determines it has a large leak, it stops recording anything other than Snores and Leaks. It also doesn’t fall into large leak mode until the leak exceeds a ~100 LPM rate and doesn’t fall out until the leak rate drops below ~90 LPM. During the period where the black bars appear above the leak rate graph line, there are no other events recorded. Under normal circumstance when I’m using a nasal mask, the leak rate doesn’t often hit a max leak value and the graph will show obstructive events randomly through the night. These events are usually Apneas or Hypopneas. This is also true for every report I have from my version of Encore Pro 1.4.91. Those other reports show that any time there is a large leak bar above the leak rate graph line, no obstructive event will be recorded and the pressure line drops to its lowest range setting.

If the machine isn’t recording events, then it doesn’t have the event logic to use to boost the pressure above the low value setting. I’m saying this because when I read the patent information for the REMStar, it stated it needed to satisfy obstructive event rules to raise the pressure. It also tries to raise the pressure if there is a persistent period of snores, but that logic requires the snores to happen within a short time window for the machine’s rules to be satisfied. In the graph example above, there is only 1-time when there is a short period persistent snore cycle and only one time when the machine tried to raise pressure.

Let’s now take a look at the logic that the REMStar is using so the process can be explained better. Click on the next link to open another image in a new browser window:
REMStar Auto Pressure Change Logic

This image was recreated from details downloaded from another thread here where the Respironics Patent information was made available. By following the process displayed in this image, it should confirm what I’ve been saying about why there isn’t any pressure increases without obstructive events unless there is short snore cycle window that gets satisfied. What isn’t clear from that image is why the pressure drops down again. To understand that logic we have to look at the optimization process the REMStar is using as part of its Safety Net process to find the most comfortable pressure level for the user, without it being so low as to cause excessive amount of obstructive events, or so high as to cause other problems. In simple terms, the machine is constantly hunting for the best pressure level during the titration period whenever it is in APAP mode.

So, if we get back to your original question, wherever you see the large leak bars, you can also see that the pressure value of the machine is on its low value setting (12cm) because it didn’t satisfy any of its rules to increase pressure. When the first break in the large leak bar occurs, the machine records an apnea event and the pressure tries to respond by increasing for a short period. Shortly after increasing, the pressure drops back to the low side. It also bounces up a few times for reasons that aren’t clear. Before long the large leak bar appears again and the pressure drops to its low range value for the rest of the night.

What has been interesting about this Ultra mask is that I don’t know there is a large leak going on, or at least I don't hear it over the normal exhaust of the mask. From the best that I can tell the mask is sealing, but it might be leaking through the beard area. I have noticed that when I wake up in the morning, I’m finding my mouth open and feeling like it is stuffed with "Cotton", with my cheeks puffed up like balloons. From the graph that morning period is when the leak rate is lowest. This is indicating a fit problem, but I think the lower straps are too tight, even though I’ve tried to be careful about only tightening them to just past the level when the leaks stops when I’m laying down and the pressure is on. Because the straps are tight to control the leak, they are pulling my mouth open when I’m most relaxed. This is why I don’t think beards work well with full-face mask that don’t use bellows like RESMed’s Activa’s bellows.

Life with a mask isn’t as simple as I would like. Does this help explain my statement? If not, please ask as I learn best from questions.

Roger, It seems your leaks start out rather high.(around 50) Is it possible the leaks might be coming out from around the humidifier. My wife and my wife's mother their leak rates looked similar to yours. There pressure stayed low with these leaks .When I examined both remstar auto. I noticed that both machines the humidifier was not set back further enough to get a good seal...ie, small leaks coming from the humidifier to the machine. I pushed the humidifier closer to the auto (to get a seal)and found that their leak rates and leaks went down to 20...........This might not have anything to do with your case but I just wanted to share it with others...Good Luck
th

th wrote:Roger, It seems your leaks start out rather high.(around 50) Is it possible the leaks might be coming out from around the humidifier. My wife and my wife's mother their leak rates looked similar to yours. There pressure stayed low with these leaks .When I examined both remstar auto. I noticed that both machines the humidifier was not set back further enough to get a good seal...ie, small leaks coming from the humidifier to the machine. I pushed the humidifier closer to the auto (to get a seal)and found that their leak rates and leaks went down to 20...........This might not have anything to do with your case but I just wanted to share it with others...Good Luck
th

Hello “th”,

I just went and looked at the humidifier and it seems to be pushed back solid against the mating union of the machine. I also looked up the designed leak rate of the Ultra Mirage Full Face mask and the manual shows that by design, the mask will leak between 40 to 45 LPM for the pressure range of 12cm to 14cm. When I use the Respironics Comfort Curve or the RESMed Activa, the leak rates fall in the range of 35 to 45 LPM. This leak issue seems to be primarily a fit problem of this mask.

You are correct about the start out rate. I’ve noticed that as well and that is what is misleading about whether there is a good fit. During the night I had a few arousal events that were probably obstructive because the pressure wasn’t where it needed to be. When I awoke I noticed my mouth was closed, but air was escaping over my cheeks. When I opened my mouth, the cheeks puffed up and the leak stopped. In checking the mask this morning, it appears that in order for me to get a good even fit on the mask seal, I would need to have the mask pivot go one more notch open, but with the current design it isn’t possible. What might be possible is to trim the silicon pad plugs that hold the forehead silicon pad in place. This would allow the top of the mask to move closer to the forehead at the top, and reduce some of the pressure on the chin. In a full open position, the bridge of the nose just barely touches so moving the mask closer at the top would help that area as well even though it does seal well near the eyes. Currently the limited movement prevents the side pads from getting close enough to the cheeks, unless I putting excessive pressure on the jaw by tightening the lower straps. After I shake this cold stuff, I’ll spend some time getting creative to see if something better can be arranged.

By the way, last night’s numbers for leaks were:
Largest Leak Minutes = 312
Percentage of Night in Largest Leak = 66.2%
Average Leak (LPM) = 85.6

When the leaks are this large and this prolonged, none of the information coming out of the machine is meaningful for understanding how to improve treatment.

Thanks for the feedback.

Oooohhhh! Love your new avatar Lori!

Ramona wrote:Oooohhhh! Love your new avatar Lori!

Thank you...much better than my mug, right??? (no need to answer )

I use the ResMed Auto Spirit along with the Hans Rudolph. The leakage with the Ultra Mirage is very high indeed.

My Hans Rudolph leakage numbers range from 0.00L/S to 0.12L/S.

You may want to try other masks for a better and quieter nights sleep.

From what I've learned about leak rates for mask, the Ultra Mirage numbers don't seem out of line for the volume of the full-face chamber. I wouldn't be surprised to learn that all full-face masks with a similar size breathing chamber also have a similar leak rate curve. Mask leakage is required because each mask must have a leak rate that can clear the chamber and upper air hose of expired air before the next breath is taken. In addition, this design leak requirement must perform reliably over a broad range of breathing cycle lengths. In simple terms, the designed leak is how the mask can exchange the air in the breathing chamber so the oxygen saturation level of the blood doesn’t drop to dangerously low levels. This air leakage happens through the mask exhaust holes. These exhaust holes don’t make much noise, but the air coming can get louder if they blow against the sheets or pillow case. By understanding a mask’s designed leak rate value, we can then evaluate how well the mask is fitting by subtracting the design’s intended number from the machine’s recorded number. In my case, my nasal mask are showing about a 50% leak rate increase over the design number as an all night average. My full face mask is still showing more than a 100% increase, but that is a serious problem because when both values are combined, the working leak rate pushes the leak number too close to the max leak number of my REMStar. When the total leak rate hits the maximum allowed leak number of the machine, it stops working as an APAP and stops recording information.

There is also an anti-asphyxia valve in full face mask that opens when the power goes out and the pressure in the mask breathing chamber drops below the pressure needed to provide the required air exchange. Over time this valve can be an unintended source of leaks and it should be checked for wear during cleaning. This anti-asphyxia valve is designed to open to room air when the pressure in the hose drops below the pressure level required to clear the chamber between inhalation and expiration. This same safety valve is also the reason why when I breathe into my full-face mask the breathing signal doesn't get to the machine so it can turn on automatically.

The absence of this valve in nasal masks is why nasal interfaces don't have any trouble in generating a breathing signal into the hose that the machine can observe so it can turn on automatically.

Roger... wrote:Hello David,
I should have put more explanation into the paragraph, but the fundamental logic reflects how my REMStar Auto w/CFLEX operates. To explain it better I’ve created a snapshot of last night’s report that shows when there is a large leak, the machine stays at its lowest set value. In my case, the low side setting is 12cm and the high side range is 14cm.

Click on this image link so the image will appear on a new page:
Large Leak Problem Example

Hi Roger

First of all, we both have the same machine and the same software reports.

I have never taken the time to inform myself as thorougly as you have as to the operating algorhythms of the REMstar. My observations were empirical and possibly flawed. I have never seen leaks as extensive as yours and apparently the machine just "shrugs its shoulders" at that point and gives up, returning to its lowest pressure level to avoid killing you by accident

My large leaks are around 50 and tend to be brief.

You probably need to lose the beard as you are leaking like a sieve.

You probably love your beard like I love my 'stache. Your choice.

Good luck in any case.

Roger... wrote:From what I've learned about leak rates for mask, the Ultra Mirage numbers don't seem out of line for the volume of the full-face chamber. I wouldn't be surprised to learn that all full-face masks with a similar size breathing chamber also have a similar leak rate curve.

Hi Roger

I tested the Hans Rudolph FF mask and was astonished at the low leakage. I don't remember the exact number anymore (and I am too damn lazy to go and have a look) but it was way lower than the Mirage. I don't know if Santa Claus would get good leak rates with a Hans Rudolph. You and he may just have a problem.

Roger...

I'm not sure what's going on with your mask, but it's obviously not good. The percentage of the night you spend in large leak is off the charts! I wish Lori or Laura would chime in here.

As for the anti-asphyxia valve, I have a full-face mask with this sort of valve as well, and my machine (RemStar Auto, like yours) has no problems turning itself on after just two or three breaths.

Also, my pressure definitely goes UP to compensate for leaks, as it's supposed to. I would imagine that perhaps when you're in Large Leak that much, the machine perhaps assumes it's been left "on" but is not being used (I've occasionally done that accidentally at night when I get up to use the restroom).

Good luck... I hope you can fix your leak problem QUICKLY, because you're probably not getting any treatment effect at all that way!

CG, you're right, the leaks are ruining treatment for Roger. He seems to be well aware of the problem, though and has been wrestling with it at least from this far back when I chimed in:

Oct 29, 2005 subject: "Getting Hosed", Day-5, A Data View

Like you, CG, I hope he gets the problem solved.