ST vs ASV - studies about risk

[SarcasticDave94]

you're welcome, tried to make it reasonably understandable...

[Sleeprider]

.. And, one would have to prove medical need due to the central apnea indicated on the PSG.

Am I correct in thinking that the ASV can also force a breath on you?

Both the pulmonologist & sleep doctor #3 said that the weird breathing thing is central apnea [if I understood them correctly], and both are suggesting a bi-level with backup. It was the sleep doctor that said I would be titrated for an ST machine; Dr P was thinking that my current machine would have a setting for backup (but it doesn't). [edit: and Dr P was looking at my SleepyHead charts; Dr #3 was looking at her own computer with my data card]

Kiwii, the ASV is unique in that it provides a backup breathing rate to resolve central apnea, but it is "adaptive", and provides pressure support in the amount needed, when needed.  The ASV is typically setup with a minimum pressure support of 3.0 cm and a maximum pressure support up to 15 cm.  This machine only provides more than the minimum PS when you need it.  So if your volume drops the machine might supply a PS of 6 to even out your inspiration, preventing hypopnea. If you have a central apnea, the machine detects the change in your breathing rate and will increase pressure support until it detects your inhale, then holds that support until you cycle to exhale.  It does not submit you to pressure support on every breath.  The auto ASV resolves complex apnea problems by providing automatic increases and decreases of the EPAP pressure preventing obstructive events.

This contrasts with the S/T which is not well suited to central apnea because it provides all the pressure support, all the time and switches to IPAP using a timed backup function. The EPAP and IPAP pressures are fixed, and there is no automatic EPAP adjustment.  People with central sleep apnea disorders are very sensitive to constant pressure support, and this machine hammers them with the full maximum pressure support on every breath.  This is great for a person with restrictive lung disease or hypoventilation because it provides most or all of the work of respiration on every breath.  People with central apnea typically do very poorly tolerating these machines because they get the PS needed to overcome a central with every breath.  It increases the number of centrals making them fully dependent on the machine's pressure support to force every breath.  

Ask Dave what that is like.  He knows first-hand.  DO NOT let them give you a S/T instead of ASV.

[Shin Ryoku]

Possibly because ST was never studied or the subject of a flawed study. 

To my knowledge, ASV was "flagged" only due to one study whose methodology and conclusions have provoked skepticism.

Has it been established that ST is of less risk to LVEF patients than ASV? I've seen nothing to suggest this is proven.

All important studies have limitations and provoke skepticism. SERVE-HF was a well-done study accepted for publication in the foremost medical journal in the world, and the conclusions were self evident.

One thing lost in some of the discussion is that a therapy which may have an increased risk of death may still be offered and chosen by a patient who fully understands the risks. See for example, Patient #3 (page 58) in this presentation: http://www.masm.wildapricot.org/resource...Morgan.pdf

[SarcasticDave94]

If at all possible, get the ResMed AirCurve 10 ASV Auto machine. I'm not going to lie and say I'd tried the ST. I pushed for ASV after pulmonary nurse was amazed I DIDN'T have ASV machine because of centrals, and I don't regret it at all. Based upon assuming it's indicated, and I think so from this thread's discussion. As noted, you'd need to CHF test to give docs a green light to proceed.

[SarcasticDave94]

FWIW PS of 3-12 working for me from first week. My sidebar is actual settings BTW.

[kiwii]

Yes, thank you both for your excellent explanations. They were easy to understand - I can attest to that!

I had the impression from the pulmonologist's description that the backup he was describing would only occur if I wasn't breathing on my own. Is it possible he was describing an ASV?

I have an appointment with him in a month which includes a lung function test. He also invited me to contact him through the portal.

I am intrigued with a comment in the split thread linked earlier [ugh! can't find the post I want], something about getting good results by using cpap + supplemental oxygen for those unable to use ASV. I do happen to have an oxygen concentrator. If he were aware of this, perhaps he would give approval (and instruction) for me to use it? He does seem very approachable, but does this sound like a reasonable request for me to make?

[Sleeprider]

I recall a member that seemingly needed ASV due to centrals. He was on CPAP and we had done all we could to optimize results. Events were still around 12 AHI with a lot of centrals. His doctor put him on oxygen at 2.5 L/min and it all cleared up. It can happen, I've seen it.
http://www.apneaboard.com/forums/Thread-...everything
https://www.ncbi.nlm.nih.gov/pubmed/8996011

[Spy Car]

Possibly because ST was never studied or the subject of a flawed study. 

To my knowledge, ASV was "flagged" only due to one study whose methodology and conclusions have provoked skepticism.

Has it been established that ST is of less risk to LVEF patients than ASV? I've seen nothing to suggest this is proven.

All important studies have limitations and provoke skepticism.  SERVE-HF was a well-done study accepted for publication in the foremost medical journal in the world, and the conclusions were self evident.

One thing lost in some of the discussion is that a therapy which may have an increased risk of death may still be offered and chosen by a patient who fully understands the risks.  See for example, Patient #3 (page 58) in this presentation: http://www.masm.wildapricot.org/resource...Morgan.pdf

To my knowledge no such studies exist for the ST machines that are prescribed as an alternative to establish they are risk-free, and--in many situations-- they are far inferior to ASV for treating the problem.

The methods of the SERVE-HF study has led to criticism of the conclusions. Many studies get published only to provoke skepticism after-the-fact.

Good science is replicable. 

Bill

[paulag1955]

What is a CHF test? What does over-titration mean?

[kiwii]

CHF is Congestive Heart Failure (I had to look it up too). I don't know about the other one.