AVAPS vs. ASV

I don't quite understand the difference between the AVAPS vs. ASV. Can someone explain, in as much technical detail as possible, how the AVAPS works?
thanks.

Not sure this is what you want, James, but here's what I understand from reading from Respironics' info; All added emphasis in the quoted responses is mine:

ASV: http://bipapautosv.respironics.com/faq.aspx

The intended use is: To provide non-invasive ventilatory support to treat adult patients with OSA and Respiratory Insufficiency caused by central and/or mixed apneas and periodic breathing.

That means people whose breathing apparatus is fine, and when they don't breathe, its because there brain doesn't give the command to breathe - or else they have some upper airway collapse as well.

How does the algorithm operate? The algorithm is based on flow. Using proven RI technologies such as Digital Auto-Trak, the flow signal is analyzed and a target flow is calculated. If the patient reaches the flow target, the device does not offer any additional pressure support. If the patient does not reach the flow target the device will dynamically change pressure support breath to breath.

Does the BiPAP autoSV operate like an Auto CPAP or Auto Bi-level device for treating obstructive events? No – The device does not have an auto-titrating algorithm to alleviate obstructive events. The innovative algorithm was designed to treat complex apnea and periodic breathing. The obstructive component of SDB is treated utilizing a clinician adjustable CPAP or BiPAP pressure level.

Is it possible to use BiPAP® autoSV™ patients with COPD, OHS and NMD? The BiPAP® autoSV™ is designed to treat complicated breathing patterns in sleep patients. Nevertheless, utilizing the 3 different pressure settings and a standard backup rate of 4 -30bpm, the device can be set similar to that of a standard S/T device. The ASV algorithm is not able to assure a volume which would be most beneficial for these types of patients.

COPD = Chronic Obstructive Pulmonary Disease ; OHS = obesity hypoventilation syndrome, NMD = NeuroMuscular Disease.
These patients have no normal breathing at all - they all have a problem getting enough volume into their lungs, even when awake, and they're are worse off when asleep. The way I understand it, they may actually have a stable breathing flow - which will lull the ASV into doing nothing - but they'll be getting to little oxygen, because of their inability to get enough air into their lungs. If you solve their volume problem, they will be ok. The Average Volume Assured Pressure Support machine assures they have the right volume, all the time. It uses the pressure support (raising IPAP) to assure the have enough air in their lungs. You can see that Respironics literature for AVAPS makes a point of how gradually these machine change the pressure in order to adapt to these patients problems. This is very different from people who are breathing merrily along, and all of a sudden have an obstruction - or simply stop breathing because their brain has suddenly decided to take a break from instructing them to breathe...

http://avaps.respironics.com/features.asp

With Average Volume Assured Pressure Support (AVAPS™), inspiratory pressure automatically changes to ensure the set tidal volume.

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Think of the ASV as a talented Jazz musician, trying to add its improvisation to the patients unexpected variations so that together they have something great going.
Think of the AVAPS as the amplification system needed for a steady, but very weak beat of drums in a Rock concert.

That's the way I understand it at this point. I hope it helps.

O.

That was a beautiful explanation, ozij. Thank you very much!!

Those links help a great deal.

Thank's Rested Gal.
Two more links:
http://www.bipap.pl/literat/AVAPS%20Presentation.pdf

AVAPS automatically adjusts the pressure support level of the patient to provide a consistent tidal volume to the patient

And this - looks even better:
http://www.colosrc.org/pdf/NonInvasive_Ventilation.pdf

AVAPS is Not autoSV (servo ventilation)
• Auto SV treats complex central apneas and periodic breathing that is seen with OSA in 15% of patients
• Uses a novel flow-based feedback strategy
• Recognizes and treats apneic periods with BiPAP
• Not for core ventilation issues as it is specifically for treating difficult apnea patients

O.

James,


The AVAPS is the machine banned has been using & IIRC he has had a lot of challenges trying to tame it to suit his needs.

The main difference that I understand exists between them is that the AVAPS tracks av tidal volume whereas the BIpapSV tracks av peak flow. The AVAPS acronym includes the words Average Volume Assured Pressure System. The AVAPS algorithm was developed as part of the Synchrony Bipap machine thus when buying a Synchrony you can buy one with the AVAPS feature.

From what I have learned, the AVAPS feature tracks volume on a breath-by-breath and can adjust pressure within a breath so as to meet an average volume (assured volume).
I am not 100% certain, but I think the AVAPS Synchrony does not offer BPM=AUTO which is a feature on your current BIpapSV. It only offers std Bipap Timed Mode.

One of the core settings you use in AVAPS mode is the Vte or target av volume and that can get set from as low as 200ml up to a max of 1500ml.

In summary, the AVAPS feature is a mode of operation of the Bipap Synchrony machine that allows you to set a target av tidal volume and the machine adjust pressure breath-by-breath in order to meet that target. http://avaps.respironics.eu/features.asp

The Bipap AutoSV machine is a model designed to address a combination of sleep disorders with the main goal being to regulate periodic breathing. The original machine was first released in 2001 and specifically targeted Cheynes-Stokes respiration. CSR is the best know form of periodic breathing (CSR = waxing & waning cycles of breathing identified by periods of increasing ventilation that ramp up to hyperventilation interspersed with periods of breathing slowdown resulting in centrals, all in a repeating pattern). The latest model has expanded that CSR target to include Complex Sleep Apnea sufferers. Its specialty is people with centrals in all their various forms (CSR, CSA & vanilla CA).

DSM

AVAPS - From the link

Inspiratory pressure automatically changes from one breath to another to ensure the set tidal volume

* To make titration process easier
* To follow disease progression and patient’s needs changes
* To improve patient’s ventilation efficacy and comfort
* To increase safety by guaranteeing an averaged tidal volume

For which patients?

* To improve sleep quality as Vt depends on sleep stages
* Obese hypoventilation patients: To compensate for changes in body position; averaged tidal volume ensured
* COPD patients: to achieve a combination of ventilation comfort and efficiency with no compromise. Get both benefits by applying “the right pressure at the right time”
* Restrictive patients: To provide the comfort and leak compensation of a pressure mode, and the safety of a guaranteed volume

AVAPS is available in the BiPAP Synchrony in S, S/T, PC and T modes.