Technical, Mask Pressure and Inhale\Exhale flow rate

mbushroe wrote: ↑

Wed Dec 12, 2018 3:54 am

I am also confused as to why the spike comes at the end of the inhale instead of the beginning. The exhale does not need any extra pressure, it can just the soft tissue out of the way go out. But if the soft tissue even starts to block the inhale, the negative pressure against the back of the tongue pulls it even tighter blocking the flow even more. It would seem that the inhale needs the most help at the start, not the end. Although that probably would make the control and feedback loops in the machine quite a bit harder stay stable. And also why such a narrow spike. Surely the inhale could use the extra pressure throughout the inhale, unless leads to over pressuring or over filling the lungs.

Like I said before, PS isn't there to avoid apnea, it's there to make breathing easier, or to increase ventilation, or to help prevent snores and flow limitations. If EPAP isn't high enough, *then* you get apnea, and nothing happens, since you never trigger the machine, so the timing of the pressure increase would be immaterial.

Whacking in to full pressure as fast as possible (150 ms) is, to me, uncomfortable, and the higher the PS, the more uncomfortable, like being kicked in the lungs (though with a small horse).

Likewise, dropping the pressure out immediately is less comfortable, because it's like having your footing yanked out from under you, instead of being lowered gently.... EasyBreathe is all about *comfort*, while still being effective for people with normal lung conditions.

mbushroe wrote: ↑

Wed Dec 12, 2018 3:54 am

I had not thought of the trigger value being a separate parameter to change. Any zero crossing detector would have to have some amount passed the zero point to be sure that the zero point had actually been crossed, not merely reached. And yes I have once or twice started then stopped an inhale and felt the machine lock into one mode then take a moment to switch back again. And there ae times when I first put the mask on that I feel like my lungs and the machine are 'negotiating' a mutually agreeable breathing patter, and then waking up in the middle of the night and noticing how natural my breathing felt. I have not notice the negotiating for some time now. I guess my body has developed a 'setting' for breathing with a bipap and as soon as I put it on automatically switches over.

There is no negotiating in the machine, There's a set trigger value, a set cycle value, (both manually settable), and TiMin and TiMax values that govern the minimum and maximum time the machine can be at IPAP (also settable). The machine doesn't change anything, it just reacts to your breathing. Now, *YOU* may subconsciously decide to vary your breathing in some fashion, but the machine doesn't change on it's own.

I urge you to get the clinical manual, and read through it, there's a lot of good information in there.

As palerider said the key thing to treating obstructive apnoea is to stop the airway obstructing. That is achieved by Epap the pressure when exhaling so the absolute minimum pressure your machine is maintaining, anything above that is called pressure support on a bilevel machine and is used to increase ventilation tidal flow or some other paramter


Also the flow rate is exactly that the amount of airflow as calculated by the machine taking mask leak rate into account.

Jas_williams wrote: ↑

Wed Dec 12, 2018 12:08 pm

As palerider said the key thing to treating obstructive apnoea is to stop the airway obstructing. That is achieved by Epap the pressure when exhaling

It's just a nitpick, but since we're being technical and all, I'd say that it's not the pressure during exhale, (which varies in a declining manner as pointed out), but it's the pressure while not inhaling... that pause between the exhale and the start of an inhalation, Also known as PEEP in the ventilator world https://www.ncbi.nlm.nih.gov/books/NBK441904/

And just for a laugh I thought I would show what an ST will do during central apnoea (Not as comfortable or pleasant as easybreath nor as effective as my ASV) I have increased the rise time here so the pressure form is not completely square as it was like being kicked in the face with a wall of air.

Jas_williams wrote: ↑

Wed Dec 12, 2018 1:28 pm

And just for a laugh I thought I would show what an ST will do during central apnoea (Not as comfortable or pleasant as easybreath nor as effective as my ASV) I have increased the rise time here so the pressure form is not completely square as it was like being kicked in the face with a wall of air.

I used to have an ST model and for grins I decided to try the back up rate mode....up until then I had been using the S mode without the back up rate.
I played with the back up rate mode maybe 3 minutes before I said to hell with that and aborted the experiment.
I suppose I would/could have eventually adjusted to it if I really needed a back up rate but I am sure glad I don't. Not fun at all and I didn't even have a big PS with it....and I didn't set a very fast rate either.

Jas_williams wrote: ↑

Wed Dec 12, 2018 1:28 pm

And just for a laugh I thought I would show what an ST will do during central apnoea (Not as comfortable or pleasant as easybreath nor as effective as my ASV) I have increased the rise time here so the pressure form is not completely square as it was like being kicked in the face with a wall of air.

Typical ST Graph.png

Yeah, I I've played with fast rise times before, I don't like them...

palerider, I tried the website apneaboard.com. I as able to get the 'secret handshake' for my machine and it worked great. I went through the extended menu and saw many additional settings, including trigger level (set to medium). I don't remember seeing a hose type over ride but they may be that confident that when they sense the heated hose they know what hose size and length are.

But when I tried to get a copy of the clinician's manual, I get getting sent to pages that wanted me to progressively dropped more and more of my browser security settings to load some strange software with no explanation. And when I finally gave up trying to get a copy of the manual, I discovered that my browser home page had been changed to some place without an obvious domain and seemingly random text string as part of the destination. And the home page was locked, so that it couldn't be changed and there were two new plugins that I did not recognize. Stopping and deleting the plugins allowed to to restore my home page. But I think that website is not a nice place.

You need to be a member of the site then whilst logged in select cpap manuals at the top of the page and follow instructions to get the manual emailed to you the site is safe if you can find out how you ended up on a less secure site I am sure apneaboard will want to know about it

Jas_williams wrote: ↑

Tue Dec 18, 2018 3:03 am

You need to be a member of the site then whilst logged in select cpap manuals at the top of the page and follow instructions to get the manual emailed to you the site is safe if you can find out how you ended up on a less secure site I am sure apneaboard will want to know about it

You do *not* need to be a member to get to the email instructions. that's a "public" service... (best thing they do, in my opinion.)

mbushroe wrote: ↑

Tue Dec 18, 2018 1:33 am

I don't remember seeing a hose type over ride but they may be that confident that when they sense the heated hose they know what hose size and length are.

You can't override the heated hose type, that would be foolish.

Remove the heated hose, and you'll see the tube type menu option show up.

mbushroe wrote: ↑

Tue Dec 18, 2018 1:33 am

But when I tried to get a copy of the clinician's manual, I get getting sent to pages that wanted me to progressively dropped more and more of my browser security settings to load some strange software with no explanation. And when I finally gave up trying to get a copy of the manual, I discovered that my browser home page had been changed to some place without an obvious domain and seemingly random text string as part of the destination. And the home page was locked, so that it couldn't be changed and there were two new plugins that I did not recognize. Stopping and deleting the plugins allowed to to restore my home page. But I think that website is not a nice place.

I have no idea what you did, but all you have to do is go to this page: https://www.apneaboard.com/adjust-cpap- ... tup-manual

and follow the simple instructions... you do have to read, all the way to where it says:

Section Three is a list of CPAP Clinician Setup Manuals available through email only. (then, in all fairness, you DO have to go all the way down to section three... and send an email, as directed.

I've *personally* sent *hundreds* of people there, and they've gotten manuals. thousands more have done it too.

Again, I've got no idea what you did, but you clearly failed to follow the simple instructions.