420E Run Question ???

[NightHawkeye]

http://ajrccm.atsjournals.org/cgi/conte ... /150/2/475

Am. J. Respir. Crit. Care Med., Vol 150, No. 2, 08 1994, 475-480.

Flow limitation as a noninvasive assessment of residual upper-airway resistance during continuous positive airway pressure therapy of obstructive sleep apnea
R Condos, RG Norman, I Krishnasamy, N Peduzzi, RM Goldring and DM Rapoport
Department of Medicine, New York University Medical Center, New York 10016.

Many patients with obstructive sleep apnea syndrome (OSAS), despite therapy with nasal continuous positive airway pressure (CPAP), have persisting daytime somnolence that may be due to a persistently elevated upper-airway resistance associated with electroencephalographic (EEG) arousals. We tested the hypothesis that elevated upper-airway resistance can be inferred from the contour of the inspiratory flow tracing obtained from a conventional CPAP circuit. This may provide a noninvasive method for determining optimal CPAP. Data were collected during a CPAP titration of an upper-airway model and in eight patients with OSAS. Estimated inspiratory resistance was calculated from esophageal pressure, CPAP mask pressure, and inspiratory flow. At high CPAP, resistance was low and inspiratory flow contour was found to be rounded. At low CPAP, resistance was high and flow contour developed a plateau suggesting flow limitation. We also noted that the CPAP pressure at which high resistance developed, and at which flow limitation appeared, showed hysteresis. We conclude that when respiration is stable, the contour of inspiratory flow tracing from a CPAP system can be used to infer the presence of elevated upper- airway resistance and flow limitation. Optimizing flow contour may be an alternative to eliminating apneas in evaluation of the optimal therapeutic level of CPAP in OSAS.

Narrowing the field of view to my particular case ...
Ozij, this seems to contradict our earlier speculation that the flow-limitation runs are related to congestion. It is however in agreement with -SWS's earlier comment that his congestion doesn't result in flow-limitation runs in his own data. I know that higher-pressure air blowing up my nose definitely helps open the airways, so intuitively the conclusions of the report make sense.

On mornings like today, my upper airway seems quite clear, yet I still had those persistent flow-limitation runs last night. Also, my sinuses have cleared up considerably since starting PAP therapy. While on the one hand I'd like to be able to see an ENT who could effect some changes to benefit my therapy, on the other hand I don't now have any obvious reason to believe that to be likely. .

Bill, I'll have a little more conjecture to submit for your thought regarding those occasional central apneas. I have three candidate hypotheses going so far, and they are not mutually exclusive.

I'd love to hear 'em -SWS. The central apneas seem to be the more dramatic part of the problems I experience now. When I first started this therapy I spent some time at the low pressure of 4 cm and benefitted immensely from that. Given my history of chronic hyperventilation, it made perfect sense to me that the higher CO2 level at that low pressure helped.

I never saw NR's in my Respironics data and until recently when you indicated that the CA's indicated by the PB420E were definitive, I was inclined to be dismissive of those as errant reporting data. I just assumed that the CA detection capability of the 420E was "crude", providing undeterminate results. Apparently, that is not the case.

One other comment was made regarding Peggy's results and shallow breathing. I believe that applies to me as well. Having a desk job and all, I tend to be rather sedentary. I notice, however, that I do much better with some exercise. There's definitely a connection, whether it's cardiac function, deeper breathing, or something else ...

You don't also happen to have any history of lower GI issues?

Not unless you count aerophagia, -SWS. I've had numerous GI tests done in the past which were all negative. Even had a colonoscopy a year or so ago No signs of problems. That was even before I found out about Cayenne pepper, btw, which has improved digestion considerably for me since then.

Regards,
Bill

[Snoredog]

Bill:

The 420e's ability is far from being crude, when it comes to CA detection and avoidance. In fact when it comes to those it is highly specific at 100%.

The 420e uses two methods to avoid any response to centrals:

-Monitoring of Cardiac Oscillations that appear in 6 out of 10 central apnea (or 62%),
-Use of the A10 parameter limiting any response in the remaining 38%.

By comparison to Resmed which only has the A10, by comparison to the Remstar which has the "crude" NRAH.

Shallow breathing makes the Flow Limitation circuits on ANY autopap go nutso. You have to make the decision on if you should respond to those FL's, that is what the IFLx settings are for.

Shallow breathing to the point of no airflow is a central. You don't have respiratory effort belts to confirm that, so out of all the machines on the market the 420e does the best job to date in identifying those events and avoiding them.

My shallow breathing used to be so bad that at sleep onset I could never get to sleep, it is what started me looking at sleep as an issue which came to a head after my first stroke.

I don't know why some people shallow breathe, never did much research on it.

[Adrian]

I just came across this thread and I'm somehow relieved I'm not the only one with lots of runs. When I started therapy using a 420E more than a year ago I noticed both the unusual high number of runs and the high percentage in flow limited cycle. At the time I had been searching the forums, but to no avail.
I'll try to post my graphs:

and Synthesis:



I had a very congested nose initially but I had septoplasty in June last year and also RF UPP. My nose is now in very good condition but the figures for runs did not change at all.

Data is a few months old as I moved the PC and didn't find time to extend the connection to the machine.

I'll appreciate any suggestions.

[pjwalman]

Please explain flow limited cycle for me, if you have time. Is it like trying to breathe around a partial obstruction? With me being in so much of it per night, SnoreDog mentioned he doubted I'd feel rested, which is of course right. Is there anything I can do to get out of it?

BTW, last two nights, I had hardly any events, period, absolutely no centrals, so I think I might have finally found my "sweet spot". Not holding my breath yet, of course, and looks like I'm moving to a new machine, so the game starts all over again, I guess.

Peggy

[-SWS]

Please explain flow limited cycle for me, if you have time. Is it like trying to breathe around a partial obstruction?

Peggy, a "flow limited cycle" is a breath with "flow limitation".

Resmed nicely describes sleep disordered breathing (SDB), including flow limitation, in this presentation:
http://www.resmed.com/en-en/clinicians/ ... 40x380.swf

Note that brain wave activity can become disturbed during sleep because of flow limited breathing. This type of sleep arousal is believed to be related to the increase in effort required to draw an adequate breath during flow limitation. A repeated sequence of flow-limitations followed by arousals can drastically impair restorative sleep for some SDB patients.

[Snoredog]

I just came across this thread and I'm somehow relieved I'm not the only one with lots of runs. When I started therapy using a 420E more than a year ago I noticed both the unusual high number of runs and the high percentage in flow limited cycle. At the time I had been searching the forums, but to no avail.
I'll try to post my graphs:

<snipped>

I had a very congested nose initially but I had septoplasty in June last year and also RF UPP. My nose is now in very good condition but the figures for runs did not change at all.

Data is a few months old as I moved the PC and didn't find time to extend the connection to the machine.

I'll appreciate any suggestions.

Have you tried raising the Maximum pressure ceiling from current 9.0 cm?

I would increase it to at least 15 cm even with those 2 centrals present.

But what I do see is AV or snoring continuing, so I would allow the machine to increase on up and take care of those, right now it looks like they are bumping up against your 9.0 cm ceiling. You are asleep when that snoring is happening so I wouldn't worry about it impacting your current therapy, but your snore index is over 101, bit too high.

Your Flow Limited cycles is close to 38% also too high in my opinion. Your target Normal cycle should be around 95%

[pjwalman]

Thanks, SWS. I've watched that thing probably three times, always for a new reason to watch, and I never seem to retain everything in my little pea brain. I will go watch it again. Appreciate the link!

Peggy

[NightHawkeye]

BTW, last two nights, I had hardly any events, period, absolutely no centrals, so I think I might have finally found my "sweet spot". Not holding my breath yet, of course, and looks like I'm moving to a new machine, so the game starts all over again, I guess.

You can always come back to the PB420E, Peggy. Your goal is to get the best therapy possible. There are a number of reasons Bi-level may not work well for you, both therapy related and comfort related.

Regards,
Bill

[pjwalman]

Comfort related, Bill? Oh, please, don't tell me that. It's not going to be more comfortable with the difference in inhale and exhale? Better prepare me now. It's just one thing after another, it seems.

Peggy

[NightHawkeye]

Comfort related, Bill? Oh, please, don't tell me that. It's not going to be more comfortable with the difference in inhale and exhale? Better prepare me now. It's just one thing after another, it seems.

Peggy

I'm sorry, Peggy. You seemed sad about switching from the PB420E. I just wanted to let you know there's nothing to be sad about.

As for bi-level, I didn't mean to scare you. Bi-level therapy is different though. Maybe what I should have said was that you might not like BiPAP as well as CPAP with the little PB420E. There's also a good chance that you'll like it better.

Regards,
Bill

[pjwalman]

Whew!!

Honestly, though, nothing about this goes very smoothly, does it? So I would be a fool to not expect another bump in the road, I'm thinking. I will be prepared and ready.

I can see, if I weren't quite so stubborn, how easy it would be to just bag it sometimes. You see people come here, talk about how hard it all is, and then you don't see them anymore, and it's sad...but you can understand it in a way. I am just so grateful that I found this specific gathering place and didn't stop at signing up for the Yahoo group I found. Nothing wrong with that group, but you wait a day before you get any feedback, and then often what you hear is, "Don't even think about making any changes to your machine. Doctors know best." Just not my way of thinking and not my way of accepting. So, at the risk of repeating myself, I consider myself very damned lucky to have searched a little farther and found cpaptalk.com where I can get support, knowledge, and sometimes a good kick in the ass to quit feeling sorry for myself.

And, about the 420E, I am eternally grateful to have had this opportunity to borrow that nice little machine, to have gotten a chance to be educated in its use and learn about SilverLining, etc. It's lovely. But I do wish it had a SmartCard feature like the Respironics. Maybe someday they'll move in that direction. I miss being able to pop my card out when I get up to go to work so I can look at my numbers. With the 420E, since my husband is still in bed when I get up to go to work, I have to wait until everyone's up and cleared out before I can investigate how I did. Always bitching about something, aren't I? But I guess I'm saying I hope I can get hooked up with a Respironics bilevel so that I can go back to using my SmartCard and reader. It works better for my lifestyle. And I hope there won't be any further treatment challenges learning to use the bilevel, but I will expect them, Murphy's Law, and be ready to fight the battle once again. It's a major PITA, though, that we have to work so hard to feel good!! I can't change it, but I sure as hell don't like it!!

Peggy

[Adrian]

...
Have you tried raising the Maximum pressure ceiling from current 9.0 cm?

I would increase it to at least 15 cm even with those 2 centrals present.

But what I do see is AV or snoring continuing, so I would allow the machine to increase on up and take care of those, right now it looks like they are bumping up against your 9.0 cm ceiling. You are asleep when that snoring is happening so I wouldn't worry about it impacting your current therapy, but your snore index is over 101, bit too high.

Your Flow Limited cycles is close to 38% also too high in my opinion. Your target Normal cycle should be around 95%

Thanks for the suggestions. I have tried higher pressures, in the past, although my titration was 8. But any pressure I set, it appears that the 420E moves to more than 90% of the time to that maximum pressure and the AHI increases.
Anyway I'll try once again and will post here results in a few days.

Adrian

[Snoredog]

...
Have you tried raising the Maximum pressure ceiling from current 9.0 cm?

I would increase it to at least 15 cm even with those 2 centrals present.

But what I do see is AV or snoring continuing, so I would allow the machine to increase on up and take care of those, right now it looks like they are bumping up against your 9.0 cm ceiling. You are asleep when that snoring is happening so I wouldn't worry about it impacting your current therapy, but your snore index is over 101, bit too high.

Your Flow Limited cycles is close to 38% also too high in my opinion. Your target Normal cycle should be around 95%

Thanks for the suggestions. I have tried higher pressures, in the past, although my titration was 8. But any pressure I set, it appears that the 420E moves to more than 90% of the time to that maximum pressure and the AHI increases.
Anyway I'll try once again and will post here results in a few days.

Adrian

IF there was anyone that ever needed their IFL1 box unchecked it's you. And if those runs didn't settle down I'd uncheck IFL2 as well. You don't really have any apnea showing up in that report above, only a few Hypopnea, you have a couple CA's on line 2 BUT those are probably caused by all the FL runs and just because they show up on the reports don't forget the machine is NOT responding to those.

I would still increase the Maximum, if you uncheck that IFL1 box that should slow down or stop the runaway pressures.

[Adrian]

IF there was anyone that ever needed their IFL1 box unchecked it's you. And if those runs didn't settle down I'd uncheck IFL2 as well. You don't really have any apnea showing up in that report above, only a few Hypopnea, you have a couple CA's on line 2 BUT those are probably caused by all the FL runs and just because they show up on the reports don't forget the machine is NOT responding to those.

I would still increase the Maximum, if you uncheck that IFL1 box that should slow down or stop the runaway pressures.

I unchecked IFL1 probably in the first month and never used it again, but I'll try increasing the pressure for a few days and then I'll try playing with IFL2.
I might have selected a wrong period, with no apnea, but you can see from synthesis that during the 5 months I had 393 apneas (AI 0.4) 525 centrals (index 0.5) and a lot of Hypopneas (almost 2000 HI 2.0)
Thanks again for the advice, in my country this condition is almost unknown, and DME only reccommends CPAPs for a local fortune.

[NightHawkeye]

Here's a chart showing the past couple of night's data I'll add into the mix here.


This data is much better (i.e., tranquil nights) than most nights. What seems to make the difference is that I got significant physical exertion both afternoons, playing 16 holes of golf the day before yesterday (time limited) and 15 holes of golf yesterday afternoon. No golf-cart for me though, I was walking the course and generally keeping pace with folks in the carts. Although not exhausted after 15 holes yesterday, I was tired enough that it seemed like a good idea to quit after finishing that 15th hole beside the parking lot.

I'm assuming that physical exertion increased respiratory drive which reduced the nightly events. In particular, no central events were scored for either night and the pressure stayed at minimum for almost the entire time, something I've observed before after consistent exercise.

Also worth mentioning is that both nights I had sufficient congestion to keep clogging up one of my eustachian tubes in the wee hours of the morning. That kept waking me up so that I finally took my mask off and went back to sleep without CPAP for another hour and a half both mornings. Both mornings I later awoke relatively refreshed without knowledge of any apnea events and without any obvious lingering effects from lack of therapy - no headache, for example.

I'm only slightly closer to understanding the runs though. If 8 cm pressure was the magic threshold, then the runs should have been reduced both nights. They weren't. The only clue is lots of aerophagia from last night even though it was short. I believe that shows an association between the runs and aerophagia. The near constant runs seem to correlate positively with my aerophagia.

Regards,
Bill (through rambling for now ...)