Newbie on AVAPS

Anyone wanting a copy of the AVAPS manual can get it here ...

Cheers

DSM

http://www.internetage.ws/cpapdata/manu ... nual-1.pdf

Bingo!

Hit 1 AHi on my first night of a 7-day trial in S/T mode only.

My 10-28-08 AVAPS setting were:
Mode: S/T (No AVAPS)
EPAP: 14
IPAP Min: 17
IPAP Max: (Not Applicable)
Tidal Volume: (Not Applicable))
BPM: 6
Inspiration Time: 3 Sec
Rise time: 6

My Encore results were:
Average EPAP Pressure: 14
Average IPAP Pressure: 17
Apnea Count: 1
Average (Exhaled) Tidal Volume: 524 ml
Average Breath Rate: 16
Average % Patient Triggered Breaths: 97%
Average Leak: 43
Average Peak Inspiratory Flow: 35

This setting was beautiful! Absolutely no IPAP/EPAP switching. Except for the noise, and higher EPAP pressure, it felt like I could have been on the Adapt SV.
I'll leave the settings the same for tonight. Perhaps wing the dials some more to see if I can get 0 AHi later on.

Banned

Banned,
Great - certainly a good result and if you are getting deep sleep then extra good.

Not sure what you meant by "Absolutely no IPAP/EPAP switching" - that seems counter intuitive if you set epap=14 & ipap=17 ?
were you meaning "no early switching " ?

Cheers

Doug

dsm wrote: Not sure what you meant by "Absolutely no IPAP/EPAP switching" - that seems counter intuitive if you set epap=14 & ipap=17 ?

Perhaps I meant early switching. But, I believe the switch I felt was a result of the extra VT being cranked out in AVAPS mode. I have turned AVAPS off for now, hence no extra VT. I will check my normal Tidal Volumes this week while in straight S/T mode. If I do turn on AVAPS again I will not exceed 110% of my average VT in S/T mode. And any event, I will not exceed an Average Tidal Volume over 550ml.

I hope you are looking through the Provider Manual so you can comment on PC (Pressure Control) mode.

Thanks!
David

David,

Have had one look at it but will need time later to absorb the nature of the settings. The AVAPS varies quite a bit from how the SV can be set. Seems to have more sub-choices for the various modes.

More later

DSM

dsm wrote:David,
The AVAPS.. Seems to have more sub-choices for the various modes.

Yeah, a dial-wingers dream!

I like the S/T (only) side of AVAPS. Using the same EPAP: 14 IPAP: 17 settings, my 10 29-08 Encore results were:

Apnea Count: 1
Average (Exhaled) Tidal Volume: 512 ml
Average Breath Rate: 16.7
Average % Patient Triggered Breaths: 100%
Average Leak: 41
Average Peak Inspiratory Flow: 34.5

I will stay at the current pressures rather than try and chase the Apnea Count to 0.

I'm a little confused. The Provider Manual says while in AVAPS mode (allows you to set Tidal Volume), "Set IPAP Min at EPAP plus 4cmH20." I'm unclear if that means that if EPAP is set at 15cmH20, then does IPAP Min have to be set at 18cmH20? What would happen if I set EPAP 15cmH20 and IPAP Min 17cmH20 (plus 3cmH20) which seems to be working pretty well?

I'm also curious that S/T (only) mode seems to give me better sleep than the Adapt SV. Also, the Tidal Volume in S/T (only) mode is generally 12ml to 28ml higher than I could get while on the Adapt SV.

Banned

Banned wrote:I like the S/T (only) side of AVAPS. Using the same EPAP: 14 IPAP: 17 settings, my 10 29-08 Encore results were:

Apnea Count: 1
Average (Exhaled) Tidal Volume: 512 ml
Average Breath Rate: 16.7
Average % Patient Triggered Breaths: 100%
Average Leak: 41
Average Peak Inspiratory Flow: 34.5

I will stay at the current pressures rather than try and chase the Apnea Count to 0.

I'm a little confused. The Provider Manual says while in AVAPS mode (allows you to set Tidal Volume), "Set IPAP Min at EPAP plus 4cmH20." I'm unclear if that means that if EPAP is set at 15cmH20, then does IPAP Min have to be set at 18cmH20? What would happen if I set EPAP 15cmH20 and IPAP Min 17cmH20 (plus 3cmH20) which seems to be working pretty well?

If epap =15 then IpapMin would be 19 (15+4) a PS of 4 for bilevel is pretty much the std recomm (SWS posted a doc re that) - I like 3 CMs as it works for me. - (epap of 15 + 3 = 18 ?)

I'm also curious that S/T (only) mode seems to give me better sleep than the Adapt SV. Also, the Tidal Volume in S/T (only) mode is generally 12ml to 28ml higher than I could get while on the Adapt SV.

In S/T mode you (patient are driving the cycling whereas in AVAPS mode the machine drives the cycling. Because you have back up set very low, and are in S/T mode, you never activate the backup (machine cycling). Clearly you are happier driving the inspiration (S). See page 3-5 table is at bottom.

Banned

In page 6-4 of the provider manual you set the volume but volume mode is machine cycle driven thus it will try to drive you. This is ok for someone with health issues that needs controlled ventilation. The machine will adjust pressure in order to achive the volume.

Also, I am not clear on the reason to set IpapMax if the volume setting has been set. If volume is driving the cycling I can't see why IpapMax is needed as the machine will normally adjust IpapCurr as it needs in order to achieve the set volume ?

DSM

Banned wrote:The Provider Manual says while in AVAPS mode (allows you to set Tidal Volume), "Set IPAP Min at EPAP plus 4cmH20." I'm unclear if that means that if EPAP is set at 15cmH20, then does IPAP Min have to be set at...

15 plus 4cmH2O (19cmH2O) according to the recommendation. Recall it is that greater or lesser pressure spread between IPAP and EPAP that ventilates more or ventilates less. The recommendation apparently wants that spread to be no less than 4 cm.

A smaller 1cm or 2cm IPAPmin spread may not hamper the machine's ability to hit your volume targets, but it might be an insufficient spread for some of the more restrictive or obstructive

I'm also curious that S/T (only) mode seems to give me better sleep than the Adapt SV...the Tidal Volume in S/T (only) mode is generally 12ml to 28ml higher than I could get while on the Adapt SV.

Maybe that Adapt SV method of targeting 90% recent average volumes did not suit your physiology for one of a variety of possible reasons. If a person hypoventilates even slightly, then the Adapt SV will target 90% of those subpar volumes---making the problem a tad worse at times.

Also, you were wondering about the difference between S/T mode and PC mode.

According to the manual S/T mode allows either the patient or machine to cycle from IPAP to EPAP, based on the IT setting as a time limit. That means if the patient triggers the EPAP transition before the IT limit, that the patient and not the machine triggers that IPAP-to-EPAP cycling. Alternately in that same S/T mode the machine may initiate that cycling from IPAP to EPAP, if the IT time limit is reached before the patient initiates expiration.

PC mode still allows for the patient to trigger the very beginning of inspiration, exactly as S/T mode above allows. However, PC mode will hold the duration of each IPAP pulse width at exactly IT seconds before cycling to EPAP (for each breath). So in PC mode, the patient is not allowed to cycle the machine over to EPAP. Rather the IT setting cycles each breath over to EPAP according to that set time.

S/T mode: IT is an upper inspiratory time limit (thus patient-variable pulse width limited by IT)
PC mode: IT is a fixed time for inspiration (fixed IPAP pulse width)

PC and S/T modes treat the beginning of Inspiration alike (patient or machine will trigger EPAP-to-IPAP transition according to backup rate). The difference lies in how the end of inspiration and thus IPAP pulse width is handled according to the IT setting.

Thank you SWS and DSM,

Sorry I messed you up when I mistakenly discussed EPAP 15cm. I meant EPAP 14cm.

When I switch on AVAPS for the additional VT, the guideline is asking me to set IPAP Min 4cmH20 above EPAP 14cm, or IPAP Min 18cmH2O. I'm hoping with the mandatory 4 cmH2O EPAP/IPAP spread that I will be able to control the current Apnea Count of 1 that I'm currently enjoying at my S/T setting of EPAP 14, IPAP 17.

Guess we won't know until Tuesday. If the Apnea Count is too high with a 4cmH2O spread, I can always reduce it to a 3cmH2O spread to see the effect.

Again, my intent will be to adjust Tidal Volume not to exceed an Average Tidal Volume of 530ml. That should be well within the AVAPS recommended, "Set Target VT to 110% of Actual VT in S/T Mode".

I like what you said about the reasons I may be getting better sleep on the S/T than the SV. In light of 0 Apneas, I thought it might be light arousals caused by the constant pressure changes.

Thanks!
Banned

-SWS wrote: S/T mode: IT is an upper inspiratory time limit (thus patient-variable pulse width limited by IT)
PC mode: IT is a fixed time for inspiration (fixed IPAP pulse width)

Thanks for the explanation, SWS.
Sounds like PC mode is not for your garden-variety AVAPS hobbyist.
I'll stick with S/T.

Banned

Must admit I am still trying to figure out what the Volume setting is for ?

If it sets the volume to be delivered which is what I understand it is for, then it would be operating like a volume ventilator and they adjust IpapCurrent pressure as needed to deliver the target volume (a true volume ventilator can have the capacity to go as high as 100 CMs - not that I believe many could handle that).

But when AVAPS allows the volume target to be set it also asks for IpapMax and that is what I dont follow. If IpapMax is set too low by an inexperienced RT, surely there will be cases where the volume target will never get met because IpapMax is too low for the machine to reach the volume target ?

The RT would have to understand the impact of adjusting INSP TIME + risetime plus epap-ipap gap and IpapMax when choosing a particular volume ?

DSM

dsm wrote:
Must admit I am still trying to figure out what the Volume setting is for ?

The RT would have to understand the impact of adjusting INSP TIME + risetime plus epap-ipap gap and IpapMax when choosing a particular volume ?

You may find some answers in the AVAPS Seminar (Power-Point Presentation) that I emailed to your gmail account earlier today. Let us know if you can host the AVAPS Seminar like you did the manual?

Banned

-SWS wrote:Recall it is that greater or lesser pressure spread between IPAP and EPAP that ventilates more or ventilates less. The recommendation apparently wants that spread to be no less than 4 cm.

Tonight is a good night to switch on AVAPS mode (Tidal Volume). I'll use the 4 cm spread as recommended.

Mode: S/T AVAPS
EPAP: 14
IPAP Min: 18
IPAP Max: 25
Tidal Volume: 200ml
BPM: 6
Inspiration Time: 3 Sec
Rise time: 6

I will start with VT of 200 ml (AVAPS minimum). My preference being not to exceed 530-550 ml Tidal Volume. Limited time with AVAPS has suggested that I do not need to dial-in 530 ml to maintain 530 ml. I'm thinking the increased IPAP Min pressure (18cm) and lower VT (200 ml) may be enough to sustain a Tidal Volume between somewhere between 500 - 550 ml.

My thought is AVAPS (in AVAPS Mode) assures an average Tidal Volume at the expense of controlling Hypopnea. AVAPS has dual variables of Pressure Control and a Flow based Volume Ventilator. Tidal Volume in AVAPS Mode is controlled by Flow (IPAP Min and IPAP Max). It may be difficult to control Hypopnea in the Flow based AVAPS mode. Hence, there may be a delicate dance between VT and AHi in AVAPS Mode. I'm hoping the lower VT will keep the Hi from getting to far out-of-whack.

Banned