Tidal Volume fluctuations...Impact on night quality.

Hello everyone,

I have a question concerning Tidal Volume. Navigating in the board, i managed to understand that Tidal Volume is the amount of air breathed...during a breath, that it's more or less 500ml, with some variations during rem stage sleep. But i'm a little bit confused about the fluctuations of this volume during the night. I noticed in some subject, where results where posted, that tidal graph curve is 'almost' flat.

On the opposite, when i look at mine, even if my overall ahi is good, my tidal seems very messy, even if the median is at 400ml:


Is there a link between this 'stressed' breathing and the fact that i'm still tired despite APAP and low AHI ?

Thanks for your advices.
Fabien.

It looks like you were gasping for a breath several times during the night (sometimes called 'cleansing breaths'). I wouldn't worry about it because the episodes are of such short duration. The important thing is that you don't fullly arouse and lay awake for a long time. Also note, that it is normal, when exiting deep sleep to REM sleep to go to the first or second level, ie. semi-wakefulness. Below is a graph of the normal stages of sleep in a healthy adult - especially take note of REM and when it kicks in and drops out:

Fabien, why do you regard your Tidal Volume breathing as "stressful breathing"?

I don't see in your graphs that you're gasping for air. But a pressure of 7 cm on CPAP is known to be on the low side for providing "enough air".

Also, check this thread:

viewtopic.php?f=1&t=91553&st=0&sk=t&sd=a

The composition of your respiration is similar to that of James B. (in that thread) in that it's composed mainly of Hypopneas and Central Apneas.Has your sleep study also indicated it?

Respiratory Effort Related Arousal (RERA)

Does it take more effort to draw more air?

Is that effort likely to cause an arousal?

If an arousal occurs does it fracture the sleep patterns?

Simply, I believe that ventilatory instability causes fractured sleep and is the main reason why so many find xPAP therapy ineffective and unusable.

Hi,

Thanks for your feedback.

As said by Todzo, i'm asking me if Tidal Volume isn't the only feedback to check sleep fracturation, as a stressed breathing can be a sign of to much activity, uncompatible with a restfull sleep.

So maybe it is why i still feel tired during the day, with an ahi of 2, since the beginning of my therapy (2 years). Also, i feel that when i dont use th APAP, i'm not tired the same way, like APAP give me fractured sleep, and non-APAP give me...apnea.

I dont mean to speak out of ignorance but your question leads me to other questions myself.

You failed to post mask leak and snore information, which I find critical in tracking down other problems. I may
be ignorant but Ive always viewed those individual explosions in tidal volume as mask leak events on my own chart.

And as I've also always believed, in effective therapy lowering AHI is only a first baby step toward your goal.

Its the EVENTS that fracture things. I can have an AHI of about 1 and have a bad night sleep, or a bad 3-4 hour sleep period.

Significant snores, a block of periodic breathing like you've got there, or an intensive period of consistent
problems like clear airway issues or even clusters of hypopneas etc, can be seriously troublesome.

Most especially for us with damaged nervous systems (whether it be central, sympathetic, autonomic, whatever). A desaturation
for whatever reason can be especially devastating even if we're talking about a small percentage overall.

I've just never looked at this whole thing as an "averaged" compliance. I mean, we can spend 99.9 percent of our day not getting
shocked, but get an electrical shock and have that event totally stress our system.

Or a night panic attack for example can flood our body repeatedly with adrenaline for example and exhaust us. Its all very complicated
and we need as much information as possible to figure out whats going on.

I try to correlated every scrap of information i can to track down problems, but as an amateur compared to others here, i still
see those individual high tidal events as leakage issues.

I totally agree with you, i've lately come to the 'sad' conclusion that lowering AHI will not be a significant improvement of sleep quality.
I can really be tired the same way with an AHI of 10, 40 events of 75% HI and 25% of CA, or a night with AHI of 2, with 10 events....

so i've come to the conclusion that my fractured sleep wasn' t mainly induced by apnea, even if i made some, which can worsening things.

But there'is something i found interesting for me to find a 'quality sleep indicator', here are the data for 2 similar night:

The usual (bad) night:


The rare (very good) night:


For both of the night, same settings: 5 cm/H2O straight CPAP, Flex 2+, No leaks, AHI= 2 / 1,5 Hypopnea / 0,5 CA.
Only the Tidal Volume form is different between these nights, the good one is really less chaotic. And the feeling during the day after is without parallel.

i've no more doubt that my sleep quality is directly linked to my Tidal Volume flow...sadly i don't know how help flaten it

Did anyone else noticed this link between sleep quality and Tidal ?

SleepyFabien wrote:I totally agree with you, i've lately come to the 'sad' conclusion that lowering AHI will not be a significant improvement of sleep quality.
I can really be tired the same way with an AHI of 10, 40 events of 75% HI and 25% of CA, or a night with AHI of 2, with 10 events....

so i've come to the conclusion that my fractured sleep wasn' t mainly induced by apnea, even if i made some, which can worsening things.

But there'is something i found interesting for me to find a 'quality sleep indicator', here are the data for 2 similar night:

The usual (bad) night:


The rare (very good) night:


After your post I will be looking more at the tidal volume strips and numbers.

For both of the night, same settings: 5 cm/H2O straight CPAP, Flex 2+, No leaks, AHI= 2 / 1,5 Hypopnea / 0,5 CA.
Only the Tidal Volume form is different between these nights, the good one is really less chaotic. And the feeling during the day after is without parallel.

i've no more doubt that my sleep quality is directly linked to my Tidal Volume flow...sadly i don't know how help flaten it

Did anyone else noticed this link between sleep quality and Tidal ?

Frankly, I tend to look at minute volumes. I am one who trains to breath in a eucapnic manner so breathing volume means a lot to me. Either way breathing stability is the goal. Big changes mean big trouble. I hope the sleep medicine community will someday finally wake up to this. I think it is the major thing that is keeping xPAP unusable for many if not most over the long term.

Hello all,

I had some good results from récents tests, that tend to confirm, at least for my type of sleep behavior, that there is a straight connection between Tidal Volume, or respiratory rate, and sleep quality.

As i wanted to smooth my 'messy' respiratory rate, i made an assumption: Auto mode and Flex setting , with variable pressures during the night, may interfere with a 'normal', 'smooth', respiratory rate. This may cause hyper or hypo ventilation, and force the brain to struggle to maintain his normal rate...again the machine !

So i goes to straight CPAP mode with no Flex, and 2 nights after, the results was clear: 7 hours of sleep, 1 AHI (only hypo) and a 'smooth' Tidal Volume and Respiratory Rate. Before, i hardly sleep 5 or 6 hours, with always 5 AHI, and a messy Respiration Rate.

And more important than numbers, i felt great during the day

As already told by other members, Flex settings are not only confort, it seems to have a real impact on results. As in my case, it can reality alter the benefits of CPAP treatment.

Fabien.

I believe that there are several other possibilities, first you are at a fixed pressure which helps not heaving the body react to different pressures all the time. I think that the hunt and peck test is turn off in CPAP mode and I think that helps also.

Check this from France:


Prevalence of residual excessive sleepiness
in CPAP-treated sleep apnoea patients: the
French multicentre study
J-L. Pe´pin*,#, V. Viot-Blanc",+, P. Escourrou1, J-L. Racineuxe, M. Sapene**, P. Le´vy*,#,
B. Dervaux##, X. Lenne## and A. Mallart""

http://erj.ersjournals.com/content/33/5/1062.full.pdf

I found this old post and thought I'd follow up to see if CPAP is still a better fit than APAP for SleepyFabien. I ask as I recently discovered the benefits of narrower pressure on tidal volume (my volumes were also quite low) with low AHI but not sleeping well.