Newbie on AVAPS

Banned,

I am totally puzzled as to running a risetime of 6. That seems to me to be equivalent to lowering the CMs through the back door ?

Wouldn't you be better off with lower ipap & risetime closer to 2 or 3 ?

Good sleeping

DSM

dsm wrote: Wouldn't you be better off with lower ipap & risetime closer to 2 or 3 ?

I previously trialed S/T and S/T AVAPS at EPAP 14 and IPAP Min 18 (separation always has to be 4cm in AVAPS mode). The Apnea Count was 7 in both modes. EPAP 15 and IPAP Min 19 has the Apnea count between 2-3.

I prefer a Rise Time of 6 because it seems to fill the mask faster/fuller. I also have a perception that it helps keep the turbinates open which I view as 'restrictive' rather than 'obstructive' in nature.

Is their a correlation between Rise Time and CmH2O? And could Rise Time effect Apnea Count?

I could always try lowering the Rise Time.

Banned

Banned wrote:

dsm wrote: Wouldn't you be better off with lower ipap & risetime closer to 2 or 3 ?

I previously trialed S/T and S/T AVAPS at EPAP 14 and IPAP Min 18 (separation always has to be 4cm in AVAPS mode). The Apnea Count was 7 in both modes. EPAP 15 and IPAP Min 19 has the Apnea count between 2-3.

I prefer a Rise Time of 6 because it seems to fill the mask faster/fuller. I also have a perception that it helps keep the turbinates open which I view as 'restrictive' rather than 'obstructive' in nature.

Is their a correlation between Rise Time and CmH2O? And could Rise Time effect Apnea Count?

I could always try lowering the Rise Time.

Banned

Banned,

Lowering risetime (taking it out to 6) lowers the volume of air delivered for each breath. Think of it as the comparison between a square wave and a sawtooth wave. For the same cycle time the sawtooth dlivers less volume. I guess if it works it works and as you mentioned (& as I too know) restricted nasal airway tends to limit the volume anyway.

Raising CMs allows more air to be delivered per preath. Risetime vs CMs is a bit like a see-saw but your ability to inhale the delivered volume will be affected by your nasal congestion.

DSM

dsm wrote: Lowering risetime (taking it out to 6) lowers the volume of air delivered for each breath. Think of it as the comparison between a square wave and a sawtooth wave. For the same cycle time the sawtooth delivers less volume. I guess if it works it works and as you mentioned (& as I too know) restricted nasal airway tends to limit the volume anyway.

Raising CMs allows more air to be delivered per preath. Risetime vs CMs is a bit like a see-saw but your ability to inhale the delivered volume will be affected by your nasal congestion.

DSM

I was unclear as to whether a Rise Time of 1 or a Rise Time of 6 delivered the most 'boost' when trasitioning from EPAP to IPAP. It felt like a Rise time of 6 gave the most boost, but I may be mistaken. I may try a Rise Time of 3, tonight.

The first PC AVAPS trial went as follows:

11-12-08 settings:
Mode: PC AVAPS
EPAP: 15
IPAP Min: 19
IPAP Max: 25
Tidal Volume: 520 ml
BPM: 6
Inspiration Time: 1.7sec
Ride Time: 6

Encore results:
Apnea Count: 4
Average EPAP: 15
Average IPAP: 19.5
Average (Exhaled) Tidal Volume: 527.5 ml

In PC AVAPS mode there appears to be less disparity between the dialed-in Tv and the resulting Tv (There was significantly more separation in S/T AVAPS mode).
I will dial-up the Tidal Volume to 530 ml, tonight. I'd like to keep the AVAPS Tv just a few ml above the S/T (only) Tv. That will ensure the machine's full ventilatory function is engaged for at least most of the night. I believe it is PC AVAPS mode that encompasses the full extent of the BiPAP AVAPS capabilities.

I will play with the Rise Time, and to a lesser extent, Inspiration Time to see if I can lower the Apnea Count.

Banned

Banned,

Risetime on almost all brands is expressed in number like 1 to 3 or 1 to 6 etc:

The 1 = 100 millisecs, 6 = 600 millisecs. Going from epap to ipap in 1 tenth of a sec (=1) is downright fast. Doing it in 2/3 of a sec (=6) is pretty slow.

You may be thinking in reverse - i.e. 6=fast & 1=slow

DSM

dsm wrote: The 1 = 100 millisecs, 6 = 600 millisecs. Going from epap to ipap in 1 tenth of a sec (=1) is downright fast. Doing it in 2/3 of a sec (=6) is pretty slow.

Thank you for the clarification, dsm!

Ahh, it's the pretty slow (=6) that feels better to me because the air seems to slowly fill my nose and 'unravel' my turbinates. Also, with the extra volume, slower felt better. The perception of a longer, deeper breath..

I found the faster (=1) too abrupt and jarring, if you will.

Tonight I will try a Rise Time of 3. Well, maybe 4.

Banned

Banned wrote:

dsm wrote: The 1 = 100 millisecs, 6 = 600 millisecs. Going from epap to ipap in 1 tenth of a sec (=1) is downright fast. Doing it in 2/3 of a sec (=6) is pretty slow.

Thank you for the clarification, dsm!

Ahh, it's the pretty slow (=6) that feels better to me because the air seems to slowly fill my nose and 'unravel' my turbinates. Also, with the extra volume, slower felt better. The perception of a longer, deeper breath..

I found the faster (=1) too abrupt and jarring, if you will.

Tonight I will try a Rise Time of 3. Well, maybe 4.

Banned

Banned,

Think of the Vpap Adapt SV as being constantly on a risetime of 1 or 2. My observations are that a fast risetime makes a difference to how sleep feels - i.e. with the Adapt SV it is a very common experience to feel one is sleeping lightly (fast rise time) but with the Bipap Avaps & Bipap SV, slowing the rise time does provide comfort and the trade off is available tidal flow. But on the Avaps, there has to be some interaction between volume & risetime & Ipap. Setting a fixed volume must affect ipapmax depending on risetime chosen.

DSM

dsm wrote: But on the Avaps, there has to be some interaction between volume & risetime & Ipap. Setting a fixed volume must affect ipapmax depending on risetime chosen.

I'm sure that is a correct statement. Using a Inspiration Time of 1.6 sec and a Rise Time of 4 in PC AVAPS mode last night felt much better than my (probably incoherent) Ti 3 sec and Rise Time 6 in S/T AVAPS mode. I now understand that Rise Time plus Inspiration Time equals Inspiration Time. No wonder it is taking me so long to titrate on AVAPS, I have to learn all the basic concepts!

I'll have to see what the Apnea Count was when I get to work.

FYI - PC Mode is exactly the same as S/T mode with the added variable of tightly controlling Inspiration Time.

Banned

Damn, I forgot to stick the card in the machine last night!

dsm could be onto something when he says Inspiration Time, Rise Time, and IPAP MAx may be linked.

PC Mode does not appear to let patient's Average Tidal Volume increase more than what the machine "thinks" is necessary.
I say that because last night I increased the Tidal Volume from 520 ml to 530ml and the Average Tidal Volume actually decreased.

11-12-08 settings:
Mode: PC AVAPS
EPAP: 15
IPAP Min: 19
IPAP Max: 25
Tidal Volume: 530 ml
BPM: 6
Inspiration Time: 1.6sec
Ride Time: 4

Encore results:
Apnea Count: 5
Average EPAP: 15
Average IPAP: 19.9
Average (Exhaled) Tidal Volume: 524.3 ml

PC AVAPS mode appears to be the 'Safemode' for excessive Average Tidal Volume.
I believe PC AVAPS mode is what the literature describes in their statement, "BiPAP AVAPS will not over-ventilate".

Dialing in more Tidal Volume in S/T AVAPS mode, the resulting Average Tidal Volume will always be 10-30 ml more.

I do find PC AVAPS mode more comfortable than S/T AVAPS mode.

Inspite of 5 AHI with AVAPS, I still find the BipPAP AVAPS a more comfortable machine than the Adapt SV (which gave me 0-1 AHi).
I definitely sleep deeper (and dream), I'm never on the edge of sleep like I was on the Adapt SVs, and so far there have been no sleep irrigularities/disturbances which I would occasionally experience on the Adapt SVs.

Banned

Banned wrote:dsm could be onto something when he says Inspiration Time, Rise Time, and IPAP MAx may be linked.

PC Mode does not appear to let patient's Average Tidal Volume increase more than what the machine "thinks" is necessary.
I say that because last night I increased the Tidal Volume from 520 ml to 530ml and the Average Tidal Volume actually decreased.

11-12-08 settings:
Mode: PC AVAPS
EPAP: 15
IPAP Min: 19
IPAP Max: 25
Tidal Volume: 530 ml
BPM: 6
Inspiration Time: 1.6sec
Ride Time: 4

Encore results:
Apnea Count: 5
Average EPAP: 15
Average IPAP: 19.9
Average (Exhaled) Tidal Volume: 524.3 ml

PC AVAPS mode appears to be the 'Safemode' for excessive Average Tidal Volume.
I believe PC AVAPS mode is what the literature describes in their statement, "BiPAP AVAPS will not over-ventilate".

Dialing in more Tidal Volume in S/T AVAPS mode, the resulting Average Tidal Volume will always be 10-30 ml more.

I do find PC AVAPS mode more comfortable than S/T AVAPS mode.

Inspite of 5 AHI with AVAPS, I still find the BipPAP AVAPS a more comfortable machine than the Adapt SV (which gave me 0-1 AHi).
I definitely sleep deeper (and dream), I'm never on the edge of sleep like I was on the Adapt SVs, and so far there have been no sleep irrigularities/disturbances which I would occasionally experience on the Adapt SVs.

Banned

I am increasingly tempted to contact Resmed to discuss their Vpap Adapt SV & why so many of us who use it find it hard to get 'deep' sleep like we get with the Bipap AutoSV even though the general therapy works weel enough. As previously mentioned, my current theory is that the Adapt SV machine's automatically controlled risetime is just too fast for many people - but if they did it for a reason (to do with targeting specific SDB segments) then at least I'll understand why. I suspect though that they were trying to simplify the settings in order to eventually produce a self setting machine requiring only epap to be set fo any type of sdb user. This is only my guess so perhaps some interaction with them may explain it.

DSM

dsm wrote:why so many of us who use it find it hard to get 'deep' sleep like we get with the Bipap AutoSV

Bear in mind that so far we only have one poster who has performed a side-by-side comparison of those two machines. We don't yet have robust numbers of anecdotes comparing those two machines by any empirical standards.

But I am elated that you have received such great results with your BiPAP autoSV, Doug!

Banned wrote:

dsm wrote: SAG

What processes over time did you go through to reach this insight

I'm guessing SAG's more relaxed demeanor toward the recreational use of BiPAP AVAPS.....
Banned

No I think he means using AVAPS is more like going to Vegas and having a good time

-SWS wrote:

dsm wrote:why so many of us who use it find it hard to get 'deep' sleep like we get with the Bipap AutoSV

Bear in mind that so far we only have one poster who has performed a side-by-side comparison of those two machines. We don't yet have robust numbers of anecdotes comparing those two machines by any empirical standards.

But I am elated that you have received such great results with your BiPAP autoSV, Doug!

I have spoken to & been in contact with, 6 other Vpap Adapt SV users. Not all of them want to discuss their use publicly.
But, there is only 1 (with whom I never raised the issue ) who has not said they noticed they slept 'lightly'. That is enough to get my attention especially when I can duplicate the condition on the Bipap Auto SV with a fast risetime.

DSM

dsm wrote: That is enough to get my attention especially when I can duplicate the condition on the Bipap Auto SV with a fast risetime.

Doug, I'm thinking the culprit might not be VPAP adapt SV rise time after all. There are multiple ways to deteriorate sleep architecture with various BiLevel pressure delivery parameters:

Resmed wrote:The algorithm uses three factors to achieve synchronization between pressure support and the patient’s breathing:
1. The patient’s own recent average respiratory rate—including the ratio of inspiration to expiration and the length of any expiratory pause.
2. The instantaneous direction, magnitude, and rate of change of the patient’s airflow, which are measured at a series of set points during each breath.
3. A backup respiratory rate of 15 breaths per minute.

Factor two above entails a flexible and matching rise time rather than fixed, since that rise time matches prior breaths based on multiple reference or set points.

However, factor three above is where Frequen ran into genuine sleep problems during her PSG with a Resmed factory rep on hand. My hunch is that factor three---fixed backup rate of 15 BPM---just may be a somewhat common patient-discomfort issue with that machine.

-SWS wrote: My hunch is that factor three---fixed backup rate of 15 BPM---just may be a somewhat common patient-discomfort issue with that machine.

yeah man bet it is, that is a bit rapid, 4 second breaths. how long is the typical pause time after exhale last?