CPAPtalk.com

Julie wrote:You may end up confusing the machine... those designations are there for a reason and it's probably not the first (or second) place to start experimenting, especially with someone else's treatment.

But that's the point, isn't it? I mean, who am I supposed to experiment on? Myself?

palerider wrote:

Pugsy wrote:

palerider wrote:
this is one spot where pugsy and I disagree, since *all resmed masks* have approximately the same vent amounts.

I know. That's why I said "mainly" and I am just going by what ResMed has always put in their literature about mask selection and leak calculations. I figure if they made a point to say it then it must have some impact or else they would do like Respironics does and make a WAG. ResMed mentions mask selection and leak calculations in the same breath...wasn't me.
You've read it too. Now do they have some other underlying thing going on????? they very well could and I am not saying you are wrong...I am just relaying what ResMed has said in the manuals.

I know.... and I have seen that.... I still feel that the whole "used in leak calculations" was for older generations of machines that weren't as smart as the s9-a10 machines are.

If all Resmed masks have approximately the same vent amounts, then there's no need for the machine to be "smart" to figure out the leak calculation without being told the mask type. In other words, if a Resmed nasal pillows mask, a nasal mask, and a FF mask all have an unintentional leak rate of approximately 33 L/min at 10 cm and you're using 10 cm of pressure and the total leak rate is actually 43 L/min, the machine doesn't need to know the mask type to figure out that the unintentional leak rate is approximately 10 L/min regardless of the mask used.

So why have the mask setting in the first place? If the mask setting is not used for leak calculations, then what *is* it used for?

palerider wrote:

robysue wrote:

palerider wrote:

raisedfist wrote:If her fixed pressure was 7 before , why not try 6 - 10 auto and see what kind of results she gets?.

lower pressure would make the already too high obstructive apneas worse... bad idea.

The bigger problem right now is the number of CAs: The CAI = 19.4 while the OAI + HI = 10.4. So she's having almost twice as many CAs as obstructive events.

And it's worth seeing if a small reduction in min pressure combined with a reasonable max pressure might work better than the current range of 7-20, particularly since the titrated pressure was only 7cm.

In addition a much smaller pressure range may make a big difference in fighting the leaks.

I would agree with you, except for a few points:

1. there is no correlation between the pressure and leaks, at the point where the pressure was at its highest, the leak rate was acceptable, when pressure started coming down, there was a LL, but not certainly not the worst one.
2. there is no correlation between periods of central apnea and pressure, highest pressure, few centrals, 7cm pressure cluster of centrals.

My point about getting the leaks under control first is that the leaks are bad enough to potentially be messing up the data. The AHI may be even worse that it appears to be. Also, getting the leaks fixed is critically important for comfort. The wife might not be sleeping very well to begin with because of the leaks. Fixing the leaks may reduce the amount of sleep-wake-junk, and the CAs might just disappear when the potential problem with SWJ is addressed.

perhaps I'm wrong but it seems that centrals are less stressful than obstructives, though one would have to examine the waveform to see whether breathing resumes gradually or with gasping after the centrals.

We will have to agree to disagree here: My impression is that real CAs are just as stressful as real OAs. And in this kind of picture, we just don't know if the CAs are real or not. But there are enough of them to warrant caution: If the CAs are real, increasing the pressure may very well make things worse, not better.

if there was any correlation between pressure and centrals or leaks, then I'd agree with you, but I don't see any correlation in that one chart.

Leaks and CAs are two INDEPENDENT problems in my view. And both need to be addressed independently of each other.

Fix the leaks, and comfort goes up and the data is more accurate. With more accurate data and less potential for SWJ, it is easier to evaluate whether more pressure is indeed warranted or whether the CAs have enough chance of being real that they need to be addressed, possibly with a different machine.

Limiting the max pressure may help fix the leaks simply because it means there's less overall variation in pressure to deal with.

Independently, limiting the max may help address the CA problem if they're related to pressure. The OP's wife was originally titrated at 7cm and most or all of the CAs happen at pressures that appear to be above 10cm. So it's possible that the OP's wife is someone who is very sensitive to xPAP pressure and too much pressure may indeed lead to more CAs in her case.

a more important question is whether or not the OPs wife has been screened for heart disease, kidney disease, or other underlying neurological causes.

This IS a good question. And it needs to be asked and answered before anybody lightly makes an automatic recommendation to increase the pressure in my opinion. So thank you for asking it Palerider since I forgot to.

TRzzz wrote: I mean, who am I supposed to experiment on? Myself?

don't all reputable mad scientists?

robysue wrote:So why have the mask setting in the first place? If the mask setting is not used for leak calculations, then what *is* it used for?

the same thing that humidifier presence, tubing size and length, antibacterial presence is used for. getting more accurate pressure delivery at the mask/person interface.

resmed does that, respironics copied it with their 'system one resistance settings' which is well documented.

resistances to airflow (humidifier, tubing, AB filter, and mask type) all affect the end pressure at the mask as a person breaths in and out.

by modeling the varying resistance to flow that the different components introduce, the machine can compensate by altering the flow profile in the blower to achieve more accurate pressure delivery.

I've measured pressure at the back of my machine, through an AB filter and 3 meters of hose, and compared that pressure to the pressure at the mask. my pressure settings at the time were 18/13 bilevel. with normal respiration, the pressure at the mask was pretty accurate swinging from around 13 up to around 18 on each inhalation. but the pressure at the machine was going from about 13 to 21cm peak. when I tried *big deep breaths* the pressure at the machine would spike up around 28cm, and still only around 18 at the mask.

if you look at the specs in the back of a bunch of resmed manuals, you'll see that the FFM have a slightly lower resistance value than nasal masks, though generally not much, and the pillow masks have even higher resistance than the nasal masks, (because the openings are smaller in the pillows... smaller openings, more resistance, thus requiring higher flow to achieve the same pressure on the far end.

it's obvious, if you think about it, that the computing power in the machines has improved greatly since the s8 machines, for instance, the older ASV machines had to have a pressure sensing tube running up to the mask, now they manage all that with more sophisticated algorithms, and less complicated hardware. if you watch the screen of a s9 vauto when you first turn it on, you can see it baselining the leak, for the first few breaths, it shows a leak with every inhalation, but within a few breaths, it figures out what the baseline is, and starts showing zero leak.

maybe I'll soon finally get around to hooking up the manometer again and seeing if I can record any difference in the pressure at the machine with different mask settings, and get some actual numbers to prove my theory right, or wrong... either way, I'll learn something

robysue wrote:

if there was any correlation between pressure and centrals or leaks, then I'd agree with you, but I don't see any correlation in that one chart.

Leaks and CAs are two INDEPENDENT problems in my view. And both need to be addressed independently of each other.

Fix the leaks, and comfort goes up and the data is more accurate. With more accurate data and less potential for SWJ, it is easier to evaluate whether more pressure is indeed warranted or whether the CAs have enough chance of being real that they need to be addressed, possibly with a different machine.

Limiting the max pressure may help fix the leaks simply because it means there's less overall variation in pressure to deal with.

I don't believe I ever implied that the leaks shouldn't be addressed.

what I said was that her leaks do not track pressure increases, her worst leaks were at lower pressures, not max... so why focus on pressure?

robysue wrote:Independently, limiting the max may help address the CA problem if they're related to pressure. The OP's wife was originally titrated at 7cm and most or all of the CAs happen at pressures that appear to be above 10cm. So it's possible that the OP's wife is someone who is very sensitive to xPAP pressure and too much pressure may indeed lead to more CAs in her case.

if her CAs seemed to be related to pressure, I'd agree with you... but the limited data does not support that hypothesis. she has CAs at all pressures, including 7 and we all know how accurate original titrations often turn out to be.

robysue wrote:

palerider wrote:

robysue wrote: [snip]

a more important question is whether or not the OPs wife has been screened for heart disease, kidney disease, or other underlying neurological causes.

This IS a good question. And it needs to be asked and answered before anybody lightly makes an automatic recommendation to increase the pressure in my opinion. So thank you for asking it Palerider since I forgot to.

There's no kidney or heart disease going on, but a neurological component is a possibility. Part of the mask leak issue may relate to her hair being tied with a hair band behind her head to keep it from looking wild when she gets up, but this big pile of hair may not be playing nice with the Simplus's "ErgoForm™ Headgear". I will hazard a guess that women might have this problem more often than men.

TRzzz wrote: There's no kidney or heart disease going on, but a neurological component is a possibility.

I still think the possibility that those CAs scored by the machine might be real is an important point to consider.

Part of the mask leak issue may relate to her hair being tied with a hair band behind her head to keep it from looking wild when she gets up, but this big pile of hair may not be playing nice with the Simplus's "ErgoForm™ Headgear". I will hazard a guess that women might have this problem more often than men.

Does the headgear look like this from the back?

If so, the pony tail should be put between the upper and lower straps. If she does that, the big pile of hair should not be an issue in terms of mask leaks.

If I recall, your wife does use a mask liner. That correct? Mask liners usually help with mask leaks.

One problem with full face masks like the Simplus is that the whole lower half of the face can relax in sleep, and once the jaw relaxes a bit too much, that can call a FFM to shift a bit and hence spring a (good sized) leak. Supposedly a chin strap can help. But before adding a chin strap, your wife might want to reexamine how she fits the mask each night. She ought to be adjusting the straps only after lying down in her normal sleep position with the machine on at her full minimum pressure. She might also want to wiggle her jaw a bit to see how good of a seal she has before she goes to sleep for the night.

robysue wrote: Mask liners usually help with mask leaks.

they certainly help quieten mask leaks... but a cloth seal can't be quite as good as a good silicone to skin seal... but they do feel better, and make leaks little 'pffftsss' instead of "SQUEEEEEEEEALS".

robysue wrote:..your wife might want to reexamine how she fits the mask each night. She ought to be adjusting the straps only after lying down in her normal sleep position with the machine on at her full minimum pressure. She might also want to wiggle her jaw a bit to see how good of a seal she has before she goes to sleep for the night.

or have OP sit up and watch, and see if he can figure out where the big problems come from, mouth dropping out of mask? mask being pushed aside by pillow, etc.

palerider wrote: but a cloth seal can't be quite as good as a good silicone to skin seal

Qualifying word is good. Because if the skin is oily the liner can help to stabilize the silicone and decrease sliding with position changes or face relaxation.

robysue wrote:Does the headgear look like this from the back?

If so, the pony tail should be put between the upper and lower straps. If she does that, the big pile of hair should not be an issue in terms of mask leaks

Good question. Yes, she puts the bulk of the hair between the upper and lower straps.

robysue wrote:So why have the mask setting in the first place? If the mask setting is not used for leak calculations, then what *is* it used for?

Ok, I just dug out the manometer, and hoses and hooked it all up.

trying to breath as regularly and evenly as I could, I put the vpap auto on pillows, breathed for 30 seconds while watching the meter and recording max readings, then did the same on FFM.

at 17/12, I saw pressures at the machine hitting 20 with FFM and 21 when set to pillows.

switching to differential mode, where I was measuring the pressure at the mask and at the machine, and trying to again breath as evenly as I could, I got a pressure difference of 3.9 with FFM and 4.6 with pillows.

changing the hose type resulted in a greater pressure difference than the mask type.

and Pugsy thought I'd never get around to it

while the mask setting may be used in the leak calcs... it most certainly does affect the flow generation profile.