Apnea Forum Posting

Posted by Mile High Airman on October 23, 1999 at 10:41:47:

After a bit of research, I ordered a Horizon AutoAdjust LT autotitrate (smart-PAP) flow generator yesterday. It's supposed to be here Tuesday, and I'll post any interesting results.

I've included in this post some of the autotitrate research material I obtained that I have not seen before on SN. Most of this information was sent to me by Cue Miller, who was kind enough to track it down and send it to me. Cue's information is attached at the end of this post.

I had been thinking of getting a ResMed/Sullivan AutoSet T, but discovered that the Horizon AutoAdjust is lighter, smaller, and much less inexpensive than the Resmed AutoSet. The ResMed AutoSet also currently won't work with a heated humidifier, though Resmed is coming out with a model in November that will.

I also obtained some very important information from a famous CPAP supplier we all know and love. Namely, that the ResMed AutoSet increments/decrements by 2cmH2O at a time as it ranges back and forth through the night trying to maintain optimal pressure. This is a huge increment/decrement. This is the size of the step my sleep lab used when it titrated me, and ever time they did this I was aroused from sleep. The Horizon, on the other hand, only steps by .2cmH20 (2/10 cmH2O) at a time, with a maximum change of 1cmH2O per mintue. This change is only 1/10 of the ResMed machine. The way I heard it phrased was that the ResMed treats you harshly, while the Horizon is a smooth machine.

I also called ResMed and was told that their machine records only three variables for readout: pressure, leaks, and hypopnea events. As can be seen below in the material provided by Cue, the Horizon records 7 variables. Another important factor mentioned below is that the Horizon has a parameterized definition of what constitues a hypopnea, which could be important for proper autotitration for some people. ResMed told me their machine has a fixed defintion of 50% flow reduction for hypopnea detection.

Cue's research follows:

Airman, here's some info on one of the autoset CPAPs that is supposed to work
with a heated humidifier. This is from (someone else's) posts on Usenet. Hope
this is helpful. -- Cue

----------------------------------------------

Tim wrote in message ...

>Hi Tim,
>
>I was just wondering how your trial with the Devilbiss Auto-adjust LT is
>going? Also, I was wondering if you might be able to tell me a few
>things about this unit. For one, what does it cost? And you say that
>it is able to detect and report central and mixed apneas. What about
>other types of obstructions, such as hypopneas? UARS RERA's? I would
>imagine that these would be harder to detect...but it is probably what I
>would need.

Hi Tim (the former 'tim_is_here' Tim!),

I'll be glad to give you a report on the DeVilbiss Auto-Adjust LT, which I
just got a couple weeks ago. I've been wanting to post about it anyway, but
have been too busy until now to do so. The unit is small and
lightweight--it would easily fit in a suitcase, and is a light grey color.
It runs quietly and makes its pressure adjustments very smoothly. My doctor
special-ordered it through the local DME, whom he does alot of business
with. Since they don't normally deal with this unit, they wouldn't do a
rental. Their purchase price was $1300, but you can get the unit from Conjo
for about $1000 the last time I checked. For a local DME, I think $1300 is
pretty good--seems like I saw someone else on here (Patrick?) who tried a
few DME's but the best he could find was $1700 on this unit.

For every night of sleep, this unit gives you the following information:

1. AHI (Apnea-hypopnea index--the average number of apneas and hypopneas
per hour)
2. Apneas (the total number of apnea events during the recording period)
3. Hypopneas (the total number of hypopnea events)
4. Mixed (the total number of events which were at least partially central
in origin--the rep told me that completely central apneas are included in
this category too)
5. Snores (the total number of snoring events)
6. Mask leak (total number of minutes spent with significant mask leaks)
7. Exhale puffs (total number of events, but I'm not sure what exhale puffs
are, or what their significance is---any guesses?)

You also get an 8-hour graph of the CPAP pressure for the night, so you can
see the peaks and valleys, approximately when they occur, and how long they
last. This will tell you whether there's alot of variation in your pressure
requirements throughout the night.

All of the above information is only kept for the past six nights, so you
need to do frequent downloads of the data if you want to have this type of
detailed data. Summarys of each night's pressure can be kept for longer.
This gives information on the average and the maximum CPAP pressure for each
night.

Of course you have the typical usage data as well, telling how many hours
you used the CPAP each night, total number of hours on the machines meter,
etc.

LIMITATIONS:

This data is only available with the appropriate software for the machine.
Also, pressures cannot be adjusted without the software. The software is
not shipped with the unit--it's a separate order number. It's designed for
physicians or respiratory therapists to use. Some medical equipment
suppliers may not let you have the software--others are more flexible. In
my case, the respiratory therapist was about to leave on vacation when the
unit arrived. He didn't have time to mess with the software (especially
since he'd never used it before), so was more than happy to give it to me so
he didn't have to deal with it. (I was more than happy, too!) I did agree
to make printouts of the data to discuss with my doctor.

The pressure information on the graph is plotted every 15 minutes based on
the average of the past 15 minutes, rather than a real-time moment by moment
tracking. So in reality, your pressure could have raised to 15, for
example, but if it only stayed there briefly, the graph might only show it
as 13 or 14 since it only displays the 15-minute average.

In summary, this unit is the best I could find in terms of giving diagnostic
data. It's quite rudimentary, but is a good start and hopefully more
auto-Paps in the future will take this concept further. If you think about
it, an auto-pap is constantly monitoring your every breath and every
respiratory event, so all the data is in there. It's just a matter of
saving the data and writing the software to make it accessible. You could
easily in the future have a built-in mini sleep study that lets you view
the airflow of every breath, (to determine abnormalities and whether they
are happening on inhale vs. exhale), and tell you exactly when every apnea
or hypopnea took place, and the length of each such event, etc. You still
wouldn't have the EEG to measure arousals or the oximeter for oxygen in the
blood, but I don't think it would be too difficult to include an oximeter in
the design of one of these machines. Enough dreaming--back to reality.

This post is getting very long, but I must mention another feature of the
DeVilbiss which I didn't fully appreciate before the purchase. The first
couple nights, it didn't raise the pressure at all, and was only sensing an
AHI of 1 or 2. I was using a low pressure of 6 cm. I knew the apnea was
still happening so began to dig into the help file that came with the
software and learned that the event detection algorithm is adjustable on
this unit. It came from the factory set with a parameter of a 50% reduction
in airflow required to qualify as a hypopnea. In researching what's normal,
I found that the ASDA standard is 50%, but also discovered that the practice
of sleep labs in scoring a hypopnea varies drastically. Some strictly
require 50%, but others have less strict requirements, and some score it as
a hypopnea event if there's an arousal related to any amount of airflow
restriction, regardless of the percentage. WELL, so much for comparing the
results of sleep studies from different labs! It could be like comparing
apples and oranges. I would guess that with better detection capabilities
and further enlightenment on UARS without outright apneas, this percentage
requirement will decrease in the future. The DeVilbiss lets you adjust the
requirement anywhere from 30% to 70% in increments of 5. When I changed it
from 50% to 40%, it began sensing my events and increasing pressures
accordingly. If I hadn't looked into it, though, the doctor would see an
AHI of 1 or 2 and say his somnoplasty cured me. I would've been bewildered
and would have written off this CPAP as not working. Now I'm trying the
30% setting and it's raising pressure high enough to explode my head, or so
it feels.(really only about 11.5 cm). The help file says that 30%
reductions are only rarely associated with arousals, so maybe I can back it
off to 40% again. At this point, I'm still fiddling with adjustments and
trying to get used to higher pressures, deal with leaks, etc., so I don't
have any hard and fast conclusions yet, but my initial observation is that
there is wide variation during the night. Sometimes I'll sleep a couple
hours staying at 7 cm, and then the pressure will spike up to 11+ for a half
hour or so. I suspect that periods of REM sleep are causing this. I had
one really good night of sleep, but nothing consistent yet--it's still too
early to draw conclusions, but I'll post when I do.

In your case, Tim, I don't know what UARS airflow reduction typically is,
but you'd definitely want to set this on 30% if you try it. I don't know if
the ResMed or other auto-paps have this feature or what their default
setting is. Since these machines can't detect arousals and other
parameters, they aren't a complete sleep study, but I like the fact it can
measure my apnea in my own bed, night after night, to give me a more
representative picture as opposed to one sleepless night in a strange lab.

Tim W.

--------------------------------------------

And here's another amplifying the previous post:

>This is really impressive. I wonder how this unit is able to track some
>of these things. For example, I wonder how it is able to tell when SDB
>has a central component when there's no band around the waist to measure
>breathing effort.

Looking into this, Tim, it apparently counts anything with an absolute
absence of airflow as a "mixed" event. If I'm reading their literature
right, obstructive apneas most usually have at least a small amount of
airflow getting through. So when there's a 100% absence, it's usually
central in origin. I haven't heard this before, so am not sure how
statistically accurate that premise is. They may also use the airflow curve
as a predictor of obstructive vs. central, since when there's an obstructive
event, you're trying to push air through, so there would be velocity changes
before, during, and after the event which would be different than central.

> As far as what exhale puffs are, I really don't know
>(no surprise there :) but maybe I can venture a guess>

I called technical support on this one, and they said it's basically a mouth
leak. You're breathing in through your nose, but exhaling through your
mouth.

>I find it fascinating that there could be as much variation
>in the pressure as you're seeing now. If that's true, that's a pretty
>good argument for an auto-Pap.
>

Yes, it is. And yet I've always known that some nights were much more worse
than others--I just had no way of measuring it before.

>In other words...in your auto-Pap
>search, which features seemed to be unique to the LT?
>

The main three I considered were the ResMed AutoSet T, the Puritan Bennett
(Mallinkrodt?) Cloud Nine, and the DeVilbiss. The Respironics Virtuoso is
quite popular, but it only works on snoring and vibrations, rather than
looking at the airflow as the others do, so I wouldn't even consider it, esp
ecially since I don't snore loudly. It also only works with the passover
humidifier made by Respironics. The Cloud Nine is brand new, and when I
called the company for information, they really didn't know anything about
it, even technical support, so I was forced to cross it off my list for lack
of information. I asked Joe at Conjo his opinion on these three, as he
sells them all, and he said although they were all good, the DeVilbiss was
on top. It can be used with any humidifier and any mask. The ResMed
reportedly is not recommended for using with humidifiers. The DeVilbiss is
also the cheapest of the three, and is the only one with the extensive data
reporting capabilities I posted previously. One advantage of the ResMed is
that settings can supposedly be changed on the unit itself, where the
DeVilbiss requires software or a clinical remote. The ResMed would have
been my second choice, as it does give a basic AHI reading for each night
and a couple other parameters. It's bigger and heavier, though. Both the
DeVilbiss and the Cloud Nine can fit easily in a suitcase. The DeVilbiss
unit is really nothing special to look at, and only has an on/off switch
plus an activate/de-activate switch on the unit. The latter switch is for
you to press if you wake up and the pressure is too high, it's like a reset
button that will take the pressure back down to the minimum setting. All
other parameters are controlled in the software.

There is a delay feature in the DeVilbiss that lets you set a certain period
up to 4 fours where the pressure won't rise--it'll stay at the minimum
setting, and then will operate as normal after the delay. Kind of like a
split night study--showing how bad the apnea is at a low pressure level vs.
otherwise. Something else to be aware of. The DeVilbiss seems to raise the
pressure in increments of 2/10ths of a centimeter. This makes it a very
smooth, gradual pressure increase that is unlikely to wake you up. I'm not
sure what the ResMed uses but I think it may be a full centimeter at a time.
The flip side, of course, is that since the increase takes longer, the
DeVilbiss may let you have a few more apneas than a machine which raises the
pressure faster. The DeVilbiss comes with a two year warranty--I don't know
about ResMed. And of course the price issue. You can compare them at
Conjo's website. Those were all factors that influenced my decision.

I had hoped to maybe do rentals for a couple months on each, so I could
compare before buying, but to my surprise, these units are pretty rare, and
hard to find at DME's--at least that was my experience.

Regards,

Tim W.

---------------------------------------------

And yet more:

Tim wrote in message ...
>Tim, you mention that the Devilbiss can be used with any humidifier or
>mask. Do you know if it can be used with nasal pillows?

Yes, they claim it doesn't matter. Any combination of masks, humidifiers,
etc. Some of these things can dampen the signal, but apparently they've
built enough cushion into the sensitivity to account for these various
factors.

>I guess you found one at a DME, but they wouldn't let you rent it? Did
>your insurance pay for it at least? I'm pretty sure that my insurance
>won't pay unless I get a unit through *them*...ya just gotta love HMO's!

No, I couldn't find any DME in my area that had one. They are special-order
purchase-only, at least from any of the DME's I contacted. And that's only
if your doctor writes a specific prescription for that model. Otherwise,
they try to pass off their favorite auto-pap instead (Respironics Virtuoso
at almost all the DME's I talked to). My ENT refers alot of business to one
particular DME, and as a favor to him I think they were willing to offer a
better price to me than most, on a special order, but they still required a
purchase, because they didn't want to get stuck with a rental unit on a
machine they didn't know anything about. Insurance of course, doesn't want
to purchase without a trial rental. For this reason, insurance also wanted
me to go with another brand. It was a BIG job to co-ordinate doctor, DME,
and insurance, but I think in the end, my doctor established medical
necessity for this particular unit due to its diagnostic capabilities and my
unusual case of apnea which has been resistant to standard treatments. They
haven't paid anything yet--still processing the claim--but I'm hopeful. The
DME is one of my approved PPO providers. With an HMO I'm sure it would be
more difficult.

>I went to Conjo's site to check the prices. It appears that Cloud Nine
>isn't sold there anymore...not that I could see, at least. Did you
>find any info on this unit online, other than at Conjo's? I went to
>the Puritian Bennett site but couldn't find anything on it at all.
>

Puritan Bennett is owned by a larger company--I think its Mallinckrodt, but
not positive of the spelling. You might do a search for that. All I ever
found was a press release about the Cloud Nine. This unit is a derivitive
of another unit that has been available outside the US for a number of
years, but this is the first introduction in the U.S. I called the
company's technical support to find out more about it, but they couldn't
even tell me what data the printouts include. They had virtually no
information on it themselves. They recommended that a sales rep might know
more. (Now that's a new one!) So I guess if you want to pursue it, maybe
you could talk to your local DME and ask them for the name of the Puritan
Bennett rep in your area. You could call him and ask questions, or if you
have a really good DME, they could ask him to give a demonstration at their
offices, and allow you to be there. That would be ideal! The reps can
easily get their hands on any of these machines.

Conjo told me that the Cloud Nine gives some numerical printouts, but
nothing graphical, and from what I can tell, not as detailed as the
DeVilbiss.

>Also, there also was another auto-CPAP at Conjo's site that I don't
>think I've ever seen you mention...the ResMed Tranquility Auto. Was
>there something about this unit that you didn't like?
>

Tim, I think that's an older unit that was originally made by Healthdyne or
some other company that was bought out. If I'm not mistaken, it doesn't
give any printouts. But I didn't really look into it much...I could be
wrong about it.

>Tim, thanks again for all the great information.

You're welcome, and if you find out more about the Cloud Nine or the
Tranquility auto-pap, please post so we can all be further enlightened!

Tim W.

Follow Ups:

• Re: Useful information about autotitrate flow generators Jeff Azzz 10/25/99 (0)

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