Bad Sleep study experience

[Ron AKA]

Finally got a sleep study scheduled and completed to figure out what was going on with all my central apneas over the past 3 months.  

In my look at your results I did not see an expanded flow rate graph of what one of your CA's looks like. Have you posted one? 

Here's a shot from a couple nights ago...

Yes, those look like real CA's to me...

[PoolQ]

I agree with everything you said about ASV. Period. What about centrals? ASV is for high central and/or complex apnea.

"Whenever the ASV machine detects abnormalities in breathing, it intervenes with just enough support to maintain the patient's breathing at 90% of what had been normal for that patient prior to the abrupt change in breathing. When the patient's breathing problem ends, the machine adjusts itself to this normalcy.

When the patient's breathing is stable, ASV provides just enough pressure support to provide an approximate 50% reduction in the work of breathing for the patient, therefore making the machine use much more comfortable for the patient"

This says nothing about airway patency. Basically because central apnea's are not caused in the airway, but can in the case of complex apnea be caused by a reaction to pressure changes or levels that cause the patient to skip a breath, or several.

The baseline that they talk about is not a pressure level, it is a BPM rate that the machine is set to, 15 BPM. During a central the ASV does indeed maintain pressure support to maintain the airway patency, but it also increases the pressure at a cycle rate of 15 BPM until the patent resumes breathing. These machines "ventilate" eg blow air into the patient, but they are not "ventilators" in that they cannot actually breathe for the patent -they just do not have the pressure available that ventilators have.

The sole purpose of an ASV machine is to treat centrals and not to support airway patency. It does support it, but this is not the reason for the machine

Ref: https://www.aastweb.org/blog/what-is-asv
they also quote directly from Resmed site
I found many sites that talk about this and this is basically my "book"

[SarcasticDave94]

ASV "tries" to trigger you into breathing, it does this by a higher that BiPAP pressure.

I think you've read the wrong book, PoolQ.  What you've been told is not an entirely correct explanation of what happens. The following relates to the Resmed machines, but I don't think the Philips are too far different:

ASV machines maintain an expiration pressure (EPAP) which is either preset (ASV mode) or varies within preset limits (ASVAuto mode). This pressure maintains the patency of the airway thus preventing obstructive apneas or hypopneas. As you inhale the machine adds additional pressure (pressure support PS) to achieve the inhalation pressure (IPAP). EPAP + PS = IPAP.  This is really not much different from a BiPAP type machine.

The machine monitors your breathing using a proprietary algorithm and increases EPAP as required to head off obstructive events. It also increases PS as required to keep your breathing regular against a baseline. On Resmed machines the baseline is your own minute ventilation and respiration rate. So PS will increase up to the preset limit if your minute ventilation drops too far.

The maximum pressure available on a Resmed machine is 25 cm H2O, which is the same as the Resmed Aircurve and Lumis machines. So the ASV can't give you a higher pressure than a BiPAP.

Correct on all when compared to what I have read for research and what I experience as an ASV patient.

[jaswilliams]

There are a few other settings for those of us with complex apnea, the min epap maintains the airway treating the obstructive apnea, the variable ipap and pressure support treat the hypopnea and CA’s

[SarcasticDave94]

There are a few other settings for those of us with complex apnea, the min epap maintains the airway treating the obstructive apnea, the variable ipap and pressure support treat the hypopnea and CA’s

Correct as well from my user's experience. The ASV addresses both obstructive and central apneas in me via EPAP and PS.

[Hojo]

Wow, some one higher up needs to hear about the tech, I'm on ASV and I don't need high pressure, in fact, I have my EPAP at the lowest setting of 4.  I don't even tolerate a high EPAP pressure (can't tolerate CPAP of greater than 5 hardly), and ASV is exactly what I need and it does so without any disruption in my sleep, it so so smooth and soothing.

When I was given the ASV I was set at EPAP of 5 and I promptly changed it down to 4.  When I saw the doc a few weeks later he saw that I had lowered it and I explained why, he said that is fine, that when they do the study they probably always use 5 as a starting point and if I don't need a higher pressure, than don't use it.

[PoolQ]

From what I can tell there is only a single point of disagreement. What is pressure support verses "support to regular breathing". An increase in pressure is used for both and yet they are quite different: pressure support is used to keep the airways open, using pressure to support regular breathing is used to maintain "Regular" breathing, baseline BPM at a 90% level until you system takes back over with a stable breathing pattern.

ASV does not have to be used for this, but it can be if needed. You may not need this. I have no idea

I suggest that anyone that is being considered for ASV therapy consult their Doctor and not depend on forum input alone to understand how they system may work for them. I am unfollowing this thread, please do you own homework.

[KCFLY]

I appreciate all the comments. I certainly have a lot to learn about ASV and what it may be able to do for me and all the discussion is helpful.

I'm just in limbo waiting for these results so my doctor and I can move forward trying to get me an ASV machine to treat these centrals. It will probably be another week before I see my sleep study results.

Everything I had read indicated lower pressures were not only possible, but quite common with ASV, so thanks everyone for confirming that. I knew that tech was way off base, but it was obvious after a few minutes that trying to have a rational discussion with her was going to be pointless. She had made up her mind, and nothing I said could possibly compare to her "years of experience". You know the type!

Hope you all had a great weekend. I'll check back in when I get my results.

[DeepBreathing]

I know that PoolQ has left the discussion, but I think it's important to point out that some of his statements above aren't correct. ASV machines are of course primarily for the treatment of central and complex apnea. However some / many people have mixed apnea - ie both obstructive and central. In my case it's about 50/50 OA and CA. Therefore ASVs do provide support for upper airway patency. This is not achieved by PS but by EPAP.

The first paragraph on the site PoolQ quoted includes the following: Adaptive Servo Ventilation (ASV) is a non-invasive ventilatory treatment option created specifically for the treatment of adults who have obstructive sleep apnea and central and/or complex sleep apnea. (Emphasis mine).

From the S9 VPAP Adapt clinical manual (again the emphasis is mine):

In ASV mode, the expiratory positive airway pressure (EPAP) is fixed at a value clinically set to maintain upper airway patency.

In ASVAuto mode, the EPAP automatically adjusts between the clinical settings of Min EPAP and Max EPAP to maintain upper airway patency.

I could go on, but I think the point is made. This is not just some academic argument - it's important that doctors and patients are aware of the way these machines work if they are to have any chance of getting the treatment correct.

[KCFLY]

Thanks for that response DeepBreathing..

After getting used the terminology with CPAP over the past year, learning how the ASV works with it's own set of acronyms has been challenging for me.  This explanation is one of the most clear I have seen.  

Thanks again!