Sandman Auto - IFL and max P. on apnea

[mindy]

Here are several parameter settings for the Sandman Auto as described in the manual:

Command on IFL enabled/disabled: this command raises the pressure if the flow is restricted (enabled).
Max P. on apnea (default 10.0 cmH20): maximum pressure on apnea command
Pres. Decrease: (Default is "FAST): decrease in pressure "FAST" or "SLOW"

I'm not sure how to use these. My current Auto range is set from 8 to 20 and I['ve left the default Max P. on apnea at 10.0 with IFL enabled and Pres. Decrease "FAST". Typical average pressure is between 8.5 to 9.3

Although my PSG showed only 1 central apnea at the very beginning of the study, with the Sandman at the current settings, My AHI ranges from 0.1 to 0.8 but I am having more centrals and "runs" (flow limitations?). I'm wondering what's the best way to proceed from here.

Previously on Respironics M-Series, I finally gave up on auto and ran it in straight CPAP mode at pressure of 13 and AHI ranged from 1.0 to 3.0. When I used it in Auto mode, the pressure seemed to keep going up no matter how high I set it.

Any help in understanding how this works and what things to try would be much appreciated!
Thanks!
Mindy

[Snoredog]

Here are several parameter settings for the Sandman Auto as described in the manual:

Command on IFL enabled/disabled: this command raises the pressure if the flow is restricted (enabled).
Max P. on apnea (default 10.0 cmH20): maximum pressure on apnea command
Pres. Decrease: (Default is "FAST): decrease in pressure "FAST" or "SLOW"

My machine is a 420e but basically the same when it comes to function:
IFL=Inspiration Flow Limitation; meaning Inspiration breath is flow limited or flattened, with IFL enabled it will pad the inspiration breath with extra pressure to round out the inspiration breath waveform, this may be felt and resemble a "puff" or pulse of air of which I can actually feel. Just night before last I woke up with too much pressure, I pushed the Ramp button pressure settled back down but before I could get back to sleep at the end of ramp I had to keep opening my mouth to relieve the pressure, finally I fired up the laptop to check the settings as I had downloaded from machine earlier, I guess before leaving Silverlining I had enabled the IFL box. I disabled, shut down the laptop and I had no problems at all with it puffing at me while falling asleep.

I think it is a setting you need to try both ways, but having it disabled works for me, I can tell the difference if it is enabled or disabled. Enabled it seems to respond to stand-alone FL's, with it disabled they have to be associated with a Hypopnea. On a 420e they show up on the Hypopnea +FL line.

I'm not sure how to use these. My current Auto range is set from 8 to 20 and I['ve left the default Max P. on apnea at 10.0 with IFL enabled and Pres. Decrease "FAST". Typical average pressure is between 8.5 to 9.3

Although my PSG showed only 1 central apnea at the very beginning of the study, with the Sandman at the current settings, My AHI ranges from 0.1 to 0.8 but I am having more centrals and "runs" (flow limitations?). I'm wondering what's the best way to proceed from here.

Sandman won't do anything with a CA. I would expect you would see more CA's on the machine than in the lab. You might want to experiment and set Pressure Decrease =Slow, CA's many times follow events, if the pressure drops rapidly the event may show up at the end of that decrease. I am not sure how much longer that would be as it doesn't appear to be documented in the manual. You don't have to worry about CA's on this machine.

Previously on Respironics M-Series, I finally gave up on auto and ran it in straight CPAP mode at pressure of 13 and AHI ranged from 1.0 to 3.0. When I used it in Auto mode, the pressure seemed to keep going up no matter how high I set it.

I run my 420e 1 cm lower on the Minimum pressure side to compensate for the lack of exhale relief like Cflex, I don't miss the flex at all.

Any help in understanding how this works and what things to try would be much appreciated!
Thanks!
Mindy

my opinion shown in blue
Maximum pressure for Command on Apnea=10; this is a fail-safe setting to avoid response to CA's. This machine uses Cardiac Oscillations to differentiate obstructive from central events. Not all CA's have a open airway to hear that Cardiac Oscillations (approx.) 61% or roughly about 6 out of 10 CA's have an open airway where that Cardiac Oscillation can be heard, the rest can be closed like a obstructive apnea, when no Cardiac Oscillation is heard it looks at this parameter before responding. If you study reports over a period of time and find the pressure responsible for the CA's you can set this just below that pressure and then machine will better respond to frank apnea. You can increase it from 10 if you don't see any CA's on your report at all. This means you can have Max. Pressure for Command on Apnea=14 and it will then respond to frank apnea all the way up to 14, by comparison, a Resmed Auto would stop at 10 cm, this machine you can set that pressure if wanted. Even at 14 cm, if a CA shows up with Cardiac Oscillation, machine won't respond to it.

[mindy]

Thanks very much, Snoredog! That's very helpful. I will carefully and slowly experiment.

Mindy

[ozij]

Rapoprt's Cardiac (Cadiogenic) Oscillations paper

When one restricts the analysis to data from patients who had more than five central apneas (27 patients), 6 patients showed cardiogenic oscillations in all their central apneas, 2 showed cardiogenic oscillations in none of their central apneas, and 19 showed cardiogenic oscillations in 51 ± 19% of their central apneas.

The present data show that detection of cardiogenic oscillations on the airflow signal during CPAP titration is a very specific (100%) and a moderately sensitive (60%) indicator of central apnea, as defined by the usual clinical criteria (a cessation of airflow during which no thoracoabdominal movement is seen)

There is continuing debate as to the mechanism of transmission of cardiogenic oscillations seen on the airflow signal. Lemke et al,12 concluded that oscillations were always present in subjects who were awake when the airway was seen to be patent by direct visualization, and were usually present in neonates thought to have central events. Obliteration of oscillations occurred during obstructive events. They concluded that cardiogenic oscillations were an indicator of airway patency but did not verify this during sleep. The absence of cardiogenic oscillations during all obstructive apneas in our data is in agreement with these findings. Morell et al11 examined only central apneas and concluded that there was no relationship between cardiogenic oscillations and airway patency. These studies suggest two different ways to explain our 60% sensitivity of finding cardiogenic oscillations in central apnea. First, in accord with the observations of Morrell et al,11 cardiogenic oscillations may not always occur in the airflow signal, even when the airway is patent. Alternatively, in accord with the observations of Lemke et al,12 the central apneas seen in our study may have been a mixture of open and closed airway central events; the 60% sensitivity may represent the percentage of events with an open airway. Our data do not allow us to address whether cardiogenic oscillations are present in an unspecified subset of central apneas or are markers of a patent airway but suggest that their presence is an indicator of central apnea (whether or not the airway is patent).

[ozij]

http://solvitcenter.puritanbennett.com/
From the Sandman Q&A part of the above site:

Question / Issue

What is the difference between Hypopnea Obs and Hypopnea CNT as detected by the Sandman Info/Auto?

Answer / Solution

The Sandman Info/Auto detects obstructive hypopnea which is determined as a 50% reduction of flow associated with either snoring or a run of flow limitation, or both. The central (CNT) hypopnea is determined as a greater than 50% reduction in flow that is not associated with a snoring or run of flow limitation.

[mindy]

Thanks much, O! I'm finally having more energy to try to understand this stuff better both for personal interest and to better tune my therapy. My impression is that the PB420 and Sandman have the capability to differentiate to some degree, at least, between obstructive and central. imho, 60% sensitivity isn't great although with 100% specificity it's not surprising to see it low. Once that house painting is done and I finish my archeological dig into my belongings, I'm going to look closely at a whole bunch of data to see if there's a pattern to the timing of the "centrals".

m

[rested gal]

Great info, ozij.

Although my PSG showed only 1 central apnea at the very beginning of the study, with the Sandman at the current settings, My AHI ranges from 0.1 to 0.8 but I am having more centrals and "runs" (flow limitations?)

If you're seeing only a few random centrals scattered through the nightly data, I wouldn't worry about those, if it were me. Nor would a lot of flow limited runs worry me. When using a 420E, my "runs" results were usually in the 300's, 400's, yet I felt very rested every morning.

Since the machine doesn't seem to be running away with IFL turned on for you, I'd think you can leave that on. I'd leave the "Max P. on apnea (default 10.0 cmH20): maximum pressure on apnea command" right where it is, at 10. You're already getting a nice low AHI, so I don't see any reason to raise the Max P. on apnea.

[mindy]

If you're seeing only a few random centrals scattered through the nightly data, I wouldn't worry about those, if it were me. Nor would a lot of flow limited runs worry me. When using a 420E, my "runs" results were usually in the 300's, 400's, yet I felt very rested every morning.

Since the machine doesn't seem to be running away with IFL turned on for you, I'd think you can leave that on. I'd leave the "Max P. on apnea (default 10.0 cmH20): maximum pressure on apnea command" right where it is, at 10. You're already getting a nice low AHI, so I don't see any reason to raise the Max P. on apnea.

Thanks, Laura!

I'm seeing "runs" in the 80's and central apneas of around 20-40 per night.

Mindy

[echo]

Mindy, you might want to post some example charts. The runs of 80 may or may not be a problem (as already discussed), but 20-40 CA's per night is starting to sound significant.... (IMHO).

Did they say anything about mixed or central apnea during your titration (or is that what you meant above by "1 central during the PGS")?

[ozij]

If you're seeing only a few random centrals scattered through the nightly data, I wouldn't worry about those, if it were me. Nor would a lot of flow limited runs worry me. When using a 420E, my "runs" results were usually in the 300's, 400's, yet I felt very rested every morning.

Since the machine doesn't seem to be running away with IFL turned on for you, I'd think you can leave that on. I'd leave the "Max P. on apnea (default 10.0 cmH20): maximum pressure on apnea command" right where it is, at 10. You're already getting a nice low AHI, so I don't see any reason to raise the Max P. on apnea.

Thanks, Laura!

I'm seeing "runs" in the 80's and central apneas of around 20-40 per night.

Mindy

Mindy,
How are you calulating you AHI? 20-40 Central apnea per night doesn't fit with a AHI of 0.1 t0 0.8. Looks to me like you're not adding them to the AHI calculation.

20-40 per night is not negligible - well maybe 20 is, but 40???

Previously on Respironics M-Series, I finally gave up on auto and ran it in straight CPAP mode at pressure of 13 and AHI ranged from 1.0 to 3.0. When I used it in Auto mode, the pressure seemed to keep going up no matter how high I set it.

Well, that figures....

Consdering the relatively low AHI you achieved at higher (limited) pressure on the Respironics, I would assume some of those Apneas/Cnt have to do with arousals caused by the flow limitations. Without seeing more data, my gut reaction would be raising the bottom pressure, carefully. The arousals interpretation, however, does not fit too well with your feeling so much better. A conundrum.

I think we could all learn a lot if you post some of your data - Sandman has the 96 hours details screen (not sure of the name there) and also a Waveform analysis - both would teach us alot. The best would be the whole PDF of course....

The fact the pressure is hovering so close to the minimum also indicates you're not snoring much.

What was your titration recommendation?
O.

[rested gal]

Mindy, if you could email a PDF file of one of your downloads to ozij, that would be great.

Sandman has the 96 hours details screen (not sure of the name there) and also a Waveform analysis - both would teach us alot. The best would be the whole PDF of course....

[Snoredog]

on the very last page of the Respironics Titration Guide they state:

CENTRAL SLEEP APNEA (CSA) IS DEFINED AS:
1. An apnea hypopnea index (AHI) greater than 5; AND
2. Central apneas/hypopneas greater than 50% of the total
apneas/hypopneas; AND
3. Central apneas or hypopneas greater than or equal to 5
times per hour; AND
4. Symptoms of either excessive sleepiness or disrupted sleep.

COMPLEXSLEEP APNEA (CompSA)
IS DEFINED AS:
A form of central apnea specifically identified by the persistence
or emergence of central apneas or hypopneas upon exposure
to CPAP or an E0470 device when obstructive events have
disappeared. These patients have predominately obstructive or
mixed apneas during the diagnostic sleep study occurring at
greater than or equal to 5 times per hour. With use of a CPAP or
E0470, they show a pattern of apneas and hypopneas that meets
the definition of CSA described above.

[mindy]

Thanks to all of you - I will post some reports once I unearth them (can't even find my computer right now - painters will be done next week and I'll be finding things again!). Hopefully I can find computer and download the data this weekend.

Mindy

[mindy]

Hi folks,

I finally got a waveform report for "show and tell" - this is last night's. Note that I made 2 changes which seem to have stabilized things so there's not much variation from night-to-night. First, I disabled IFL. I also increased the pressure to limit the pressure increases to 11 from 10.5.




I'd much appreciate any comments on this.

Mindy

[ozij]

Mindy
I only see those leak peaks when I mouth leak - I know I do because it wakes me up with a painfuly dry mouth. I wonder if you're not opening your mouth in an attempt to breathe when the pressure is not enough - have you considered raisning teh min. by 0.5?

O.