ResMed VPAP Machine Family Tree

[rogelah]

The article on MDA, Quest Volume 5 Number 6, promotes Bi-level S/T and states that volume support may be needed as muscle weakness progresses. I guess that volume support can be supplied by adapt SV as well as AVAPS.

Just a note, the thoracic muscles contract during exhalation as the diaphragm relaxes to promote emptying the lungs.

[jnk]

. . . Just a note, the thoracic muscles contract during exhalation as the diaphragm relaxes to promote emptying the lungs. . . .

That can happen for some, and may be happening for you, as ozij explained.

And as Wikipedia explains:

"Muscles of expiration
"During quiet breathing, there is little or no muscle contraction/relaxation involved in expiration. This process is simply driven by the elastic recoil of the lungs in healthy individuals. In certain conditions the elasticity of the lung can be lost, such as in emphysema. Forced (active) expiration occurs in such individuals as well as occurring during exercise."

[-SWS]

Just a note, the thoracic muscles contract during exhalation as the diaphragm relaxes to promote emptying the lungs.

Good point! Normal expiration is a matter of entirely passive muscular contraction rather than active (as ozij and jnk mentioned). And that passive muscular contraction during expiration is called "elastic recoil". Think of a stretched spring: it takes active muscular work on our part to get the spring to stretch; but the recoil process or contraction of that stretched spring is completely passive regarding our own muscular effort.

However, if expiration must be actively assisted or forced for any reason, then orchestrated muscle work can, indeed, come into play by the expiratory "accessory muscles" (both abdominal muscles and intercostals). Active muscular assistance by the expiratory accessory muscles can very much come into play for certain diseases that impact respiration.

I guess that volume support can be supplied by adapt SV as well as AVAPS.

The Resmed adapt SV and the Respironics BiPAP autoSV are each other's near equivalents. Those two SV machines are not really targeted for sustained volume problems. Both of those SV machines employ very short time-window flow targeting toward normalizing central breathing that tends to stem from short-term or fast-acting ventilatory overshoot/undershoot issues in central dyscontrol.

If the etiology of your FSHMD central dyscontrol is based more in prolonged volume insufficiency, then the two SV machines with their very short-term flow targeting approach may not at all be your best choice. Prolonged neuromuscular volume inefficiencies, and resulting central apneas, are typically treated with a BiLevel machine in ST mode, or even a volume-targeted ventilator in more severe cases. However, your FSHMD seems to have a good prognosis in general.

The article on MDA, Quest Volume 5 Number 6, promotes Bi-level S/T and states that volume support may be needed as muscle weakness progresses.

I would strongly suggest that your doctors research the AVAPS machine, which is even better for prolonged volume problems (and the central dysregulation that often results) than the Bi-Level S/T or the two SV type machines mentioned. The AVAPS machine really is a BiLevel S/T machine---with an added "long-window" volume assurance feature that can be either used or disabled according to what works best. My hunch is that volume assurance offered by AVAPS might come in very handy for you. Currently, there is no AVAPS equivalent in the Resmed line up.

Good luck!

[rogelah]

Thanks, I need to be reminded every so often that I am not a jack of all trades nor a master of any.

[rogelah]

Interestingly, the titration was done on Respironics Synchrony. I don't know if it had the AVAPS ability or if they tried AVAPS if it did. One thing I did learn today is that SV (servo-ventilation) is contraindicated in neuromuscular disease.

Ordinarily, FSHMD does not involve ventilation problems. Starting February, I began to have signs of muscle weakening, such as muscle twitching and reduced abiliiy to inhale. My progressive wasting of muscle has come in clumps. Just another detour on my way to becoming a centenarian!

[jnk]

For some reason, I get an error message when I click on the link ozij provided, but this link works for me:

http://bipapavaps.respironics.com/

[-SWS]

Well, you'll have to find out from your doctors if there are any additional breathing issues that are completely unrelated to your FSHMD. But the article you cited is a classic case of employing Bi-level S/T to address ventilation problems that are based in MD's neuromuscular etiology:

The article on MDA, Quest Volume 5 Number 6, promotes Bi-level S/T and states that volume support may be needed as muscle weakness progresses.

In general, xPAP machines are used to 1) stent the airway to address obstructions and/or 2) assist with lung ventilation. So if yours is purely a case of stenting the airway open then CPAP or BiLevel S (spontaneous mode) is indicated. However, if your muscles need assistance with ventilation, but not central timing, then BiLevel S (spontaneous mode) will generally suffice for that job as well. Spontaneous BiLevel can nicely provide mechanical unloading without providing any central timing assistance.

On the other hand, if central timing persistently becomes skewed/dysregulated because of those sustained respiratory volume problems (based in neuromuscular etiology), then BiLevel S (spontaneous mode) may not even suffice toward normalizing that central dyscontrol. In other words, mechanical unloading alone may turn out to be insufficient in some MD cases. Under those circumstances, BiLevel S is most often superseded by BiLevel S/T modality----or even AVAPS (which actually is BiLevel S/T modality, with sustained volume assurance thrown in for good measure).

However, I can't see using either SV machine, unless your breathing problems are surprisingly unrelated to neuromuscular disease.

[ozij]

For some reason, I get an error message when I click on the link ozij provided, but this link works for me:

http://bipapavaps.respironics.com/

Thank you, jeff, I fixed the original.

O.

[-SWS]

Starting February, I began to have signs of muscle weakening, such as muscle twitching and reduced abiliiy to inhale. My progressive wasting of muscle has come in clumps.

In light of that comment, I would add that respiratory muscle weakening or dyscontrol in sustained "clumps" can be a very compelling reason for your doctors to at least consider AVAPS.

If there's no secondary central dysregulation involved whatsoever, then the AVAPS machine can be set up in purely spontanous BiLevel mode---with volume-assurance optionally employed in tandem with that spontaneous BiLevel mode (versus BiLevel S/T mode to additionally assist with any secondary central timing issues).

So the volume-assurance feature on the AVAPS machine can help adaptively and mechanically "unload" either episodically sustained or even progressive weakening/dyscontrol of the respiratory muscles. Here we have volume assurance periodically kicking in to help with sustained hypoventilation---that can occur from prolonged spells of respiratory muscle weakening or dyscontrol. So permanently sustained respiratory muscle weakening is addressed by the base IPAP and EPAP levels. Sustained episodes or progression are then additionally addressed by the AVAPS volume-assurance feature---automatically adjusting BiLevel IPAP pressure on a temporary but more prolonged basis than either Servo Ventilation machine is designed to adaptively target (with SV's short-basis flow targeting that can be short-sighted when addressing persistent hypoventilation type problems presented by neuromuscular disease).

So in the case of certain types of neuromuscular disease progression, the AVAPS volume-assurance feature can nicely step up volumes until you can permanently change your IPAP and EPAP values. In the case of episodic spells of muscle dyscontrol or weakening (versus permanently sustained progression), the IPAP and EPAP values don't need to be manually changed. You just rely on the volume assurance feature of AVAPS to address those sustained episodes of respiratory muscle weakening or dyscontrol.

However, if secondary central apnea occurs as well, then you would run the AVAPS machine that same way---but with BiLevel S/T as your base modality instead of BiLevel S. Again, that AVAPS machine's optional volume assurance feature can be disabled, leaving you with ordinary BiLevel S or ordinary BiLevel S/T---according to what works best for you. Less commonly employed T and PC modes are available on that AVAPS model as well.

However, AVAPS machines are not at all inexpensive:
https://www.cpap.com/productpage-bundle ... undle.html

Quoted prices are supposedly cheaper than those manufacturer-imposed advertised prices. Unfortunately I have no clue how much cheaper.

[dsm]

The more this thread has evolved the more sense the AVAPS machine makes.

The other posters have summed it up very well. Just to restate what makes the AVAPS different ...

AVAPS offers the same features as a timed bilevel but includes a pressure support algorithm that can adjust ipap steadily.
The driver for the algorithm doing this is that the RT can dial into the settings an 'assured' tidal volume (say 550ml) and the avaps feature
will try to maintain that as a minimum flow. Also as mentioned earlier, the AVAPS can take some getting used to.

It acts like a volume ventilator (whereas the ASV machines are Pressure Ventilators working to an averaged target of volume / flow & rate)

Good luck

DSM

#2 corrected wording re speed of adjustment (tks SWS)

[Pugsy]

However, AVAPS machines are not at all inexpensive:
https://www.cpap.com/productpage-bundle/ ... undle.html

Quoted prices are supposedly cheaper than those manufacturer-imposed advertised prices. Unfortunately I have no clue how much cheaper.

Little less than half of the required advertised price. So a substantial knock down in price. Don't remember exact numbers but just a tad over $3K

[-SWS]

Just to restate what makes the AVAPS different ... AVAPS offers the same features as a timed bilevel but includes a pressure support algorithm that can rapidly adjust ipap (breath-by-breath).

Doug, many thanks for that summary. As it turns out, the AVAPS doesn't rapidly adjust IPAP like the SV machines. Rather, Respironics claims an IPAP adjustment rate of only 0.5 to 1 cm per minute.

The algorithm calculates the change in pressure needed to achieve the target tidal volume then slowly increases or decreases the IPAP pressure to achieve the proper pressure support.
________________________

...the algorithm slowly increases or decreases inspiratory pressure for each breath (0.5 to 1 cm H2O/min) in order to achieve the preset tidal volume.

However, AVAPS machines are not at all inexpensive:
https://www.cpap.com/productpage-bundle/ ... undle.html

Quoted prices are supposedly cheaper than those manufacturer-imposed advertised prices. Unfortunately I have no clue how much cheaper.

Little less than half of the required advertised price. So a substantial knock down in price. Don't remember exact numbers but just a tad over $3K

Thanks for that as well, Pugsy! That's a much larger discount than I would have guessed.

[rogelah]

Respironics has a home ventilation device, Trilogy 100, that has all the functionality as the AVAPS. It also has volume modes AC, SIMV (w/PS) and AC. Does anyone know what these volume modes are?

[-SWS]

Respironics has a home ventilation device, Trilogy 100, that has all the functionality as the AVAPS. It also has volume modes AC, SIMV (w/PS) and AC. Does anyone know what these volume modes are?

Here are the volume ventilator modes described:
http://www.corexcel.com/courses/body.vent6.htm

Also, page 6 in this document briefly summarizes the pros and cons of BiLevel Pressure Support Machines versus Volume Ventilators:
http://cvppsg.org/library/breathingproblems.pdf

AVAPS is really a Pressure Support machine that employs volume as a secondary target. However, I think of AVAPS as a hybrid machine somewhere between a volume ventilator and a more traditional pressure-support BiLevel machine.

[dsm]

Just to restate what makes the AVAPS different ... AVAPS offers the same features as a timed bilevel but includes a pressure support algorithm that can rapidly adjust ipap (breath-by-breath).

Doug, many thanks for that summary. As it turns out, the AVAPS doesn't rapidly adjust IPAP like the SV machines. Rather, Respironics claims an IPAP adjustment rate of only 0.5 to 1 cm per minute.

The algorithm calculates the change in pressure needed to achieve the target tidal volume then slowly increases or decreases the IPAP pressure to achieve the proper pressure support.
________________________

...the algorithm slowly increases or decreases inspiratory pressure for each breath (0.5 to 1 cm H2O/min) in order to achieve the preset tidal volume.

However, AVAPS machines are not at all inexpensive:
https://www.cpap.com/productpage-bundle/ ... undle.html

Quoted prices are supposedly cheaper than those manufacturer-imposed advertised prices. Unfortunately I have no clue how much cheaper.

Little less than half of the required advertised price. So a substantial knock down in price. Don't remember exact numbers but just a tad over $3K

Thanks for that as well, Pugsy! That's a much larger discount than I would have guessed.

SWS Thanks for that correction. I had always assumed the adjustment was quick. So much to learn

DSM