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Do FlowLimits/Hypopnea always disrupt sleep ?
#1
Do FlowLimits/Hypopnea always disrupt sleep ?
I can see how a full-stop apnea can disrupt sleep cycles, but is it a fact that all hypopnea also do the same ?  What about Flow Limits ?  Surely people are different,  and some can tolerate more limitation (FL's or H's) than others ?
Without knowing one's personal "trigger point",  how do you go about setting a personal hard limit on what we want to see ?

I think I suddenly further appreciate why the pros here are often asking "But, how do you *feel* with those settings ?"
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#2
RE: Do FlowLimits/Hypopnea always disrupt sleep ?
I too  appreciate the question "but how do you feel (aside from the numbers)?"

Others and I have pointed to a surprising Sao Paulo study from which comes this quotation from one abstract:

"There were 95% of normal individuals who exhibited IFL during less than 30% of the total sleep time. Body mass index was positively associated with IFL. Inspiratory flow limitation can be observed in the polysomnography of normal individuals, with an influence of body weight on percentage of inspiratory flow limitation. However, only 5% of asymptomatic individuals will have more than 30% of total sleep time with inspiratory flow limitation. This suggests that only levels of inspiratory flow limitation > 30% be considered in the process of diagnosing obstructive sleep apnea in the absence of an apnea-hypopnea index > 5 and that < 30% of inspiratory flow limitation may be a normal finding in many patients."
I have no particular qualifications or expertise with respect to the apnea/cpap/sleep related content of my posts beyond my own user experiences and what I've learned from others on this site. Each of us bears the burden of evaluating the validity and applicability of what we read here before acting on it.  (Disclaimer use permitted by sheepless)

 
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#3
RE: Do FlowLimits/Hypopnea always disrupt sleep ?
When they say FL >30%, is that 0.30 on the FL graph in Oscar ?

Stating that "flow limitation can be observed in the polysomnography" and then concluding that FL>30% is instructive on diagnosing OSA even if AHI <5,  would imply that the "observed" means disruption in sleep vs just being able to note the event ? 
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#4
RE: Do FlowLimits/Hypopnea always disrupt sleep ?
I was in an online conservation with Dr. Barry Krakow' and asked him what his criteria was for UARS. He had his patients come into his sleep clinic to titrate them for a rounded breath form (OSCARs Flow Rate). I asked what his criteria was. His response was to determine how the patient felt and 90% rounded breath forms.
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#5
RE: Do FlowLimits/Hypopnea always disrupt sleep ?
Is that .30 on the flow limit chart,. No.
The FL chart is a flatness index ResMed uses to automatically to manage pressure changes.

It is via a manual review of the flow rate chart.
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#6
RE: Do FlowLimits/Hypopnea always disrupt sleep ?
When I did my ResMed ApneaLink home study 7-1/2 years ago, some of the statistics were
  • total number of breaths -- 6324
  • number of flow-limited breaths without snore -- 3824
  • number of flow-limited breaths with snore -- 164
The study output said that "Normal" is considered
  • % of flow-limited breaths without snore -- "Approx 60%"
  • % of flow-limited breaths with snore -- "Approx 40%"
...which means that if you have 60% and 40%, then 100% of your breaths are flow-limited, and that's considered normal!


Really?!?

This has left me scratching my head for the last 7.5 years, LOL.

I will say that my ResMed autoset reports every breath while I'm running the machine as being in one of three states:
  • asleep in flow limitation
  • asleep in apnea
  • awake
But apparently that's normal...

Also I have noticed that none of my in-lab sleep studies have mentioned flow limits at all.
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#7
RE: Do FlowLimits/Hypopnea always disrupt sleep ?
The AHI is the number of hypopneas per hour of sleep measured during the study. It's usually measured in terms of the number of incidents per hour. The severity of OSA is classified as follows based on the AHI:
AHI 5 per hour (none/minimal).
AHI 5 (mild), but 15 per hour
Moderate: AHI 15 to 30, but no more than 30 per hour
AHI 30 per hour is considered severe.
The Respiratory Disturbance Index (RDI) is sometimes employed. This can be perplexing because the RDI includes not only apneas and hypopneas, but also other, less obvious breathing disturbances. As a result, a person's RDI may be higher than their AHI.
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#8
RE: Do FlowLimits/Hypopnea always disrupt sleep ?
(10-19-2021, 04:29 PM)cathyf Wrote: When I did my ResMed ApneaLink home study 7-1/2 years ago, some of the statistics were
  • total number of breaths -- 6324
  • number of flow-limited breaths without snore -- 3824
  • number of flow-limited breaths with snore -- 164
The study output said that "Normal" is considered
  • % of flow-limited breaths without snore -- "Approx 60%"
  • % of flow-limited breaths with snore -- "Approx 40%"
...which means that if you have 60% and 40%, then 100% of your breaths are flow-limited, and that's considered normal!

I would read that to mean that about 63% of your breaths were flow-limited, and that of those 3988 flow-limited breaths 4.1% were accompanied by a snore as opposed to the normal level of snoring during flow-limited breathing which would be 40%.

-Neelix
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#9
RE: Do FlowLimits/Hypopnea always disrupt sleep ?
- Hi, Davecar
interesting point..

What about Flow Limits ?  Surely people are different,  and some can tolerate more limitation (FL's or H's) than others ?
Without knowing one's personal "trigger point",  how do you go about setting a personal hard limit on what we want to see ?

I think I suddenly further appreciate why the pros here are often asking "But, how do you *feel* with those settings ?"


_ this is the world I have been living after 4 years: able to got pretty no recounted AHI, no FL in both maximum (maximum always < 0,1), and p95 (always zero) columns. And, yet, keep awakening a lot, in particular interrupting/truncating REM stages;
_ therefore, pretty much no tolerance at all to any FL or quasi-hypopneas, kind I would suffer of Geer1's second type of RERA, very likely associated with hypersensitive nervous system;
_ no solution on BIPAP's domain (or ASV), I think. Clonazepam 0.4 mg has been doing good job to calm down the nervous system, more normal flow rate in REM, etc, and returning me something around 90% solution, and good "how you feel index" almost all days.

all the best and good luck.
Mper
I am not a doctor. Nothing that I say here is medical advice
All my posts include only outcomes/learnings from my own/other therapies and medical literature



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#10
RE: Do FlowLimits/Hypopnea always disrupt sleep ?
(10-18-2021, 11:12 PM)DaveCar Wrote: When they say FL >30%, is that 0.30 on the FL graph in Oscar ?

Stating that "flow limitation can be observed in the polysomnography" and then concluding that FL>30% is instructive on diagnosing OSA even if AHI <5,  would imply that the "observed" means disruption in sleep vs just being able to note the event ? 

It's saying 30% of the sleep time, not .3 of 0 to 1 scale of severity of the flow response.

Greater than 30% of sleep time in IFL is a criteria for sleep apnea if AHI is lower than 5, according to them.

What is IFL is not specified.

What consitutes normal? Normal is not considered apnea? The 95% with less than 30% of time is normal?

Studies depends on sampling size.

There is no significance of this info withojt the details
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