Newbie on AVAPS

-SWS wrote:Doug, I honestly appreciate that humorous razzing.

Okay, let's make it a point to explore and discuss PB some more in the near future. But it's going to take me a while to catch up with off-line work before I can have an in-depth discussion of any kind. I look forward to a PB discussion!

echo wrote:[Pause in highly technical discussion for noob comment]

Just wanted to say thanks Doug for posting the info on PB and VB... and then a to SAG and SD for going and getting me all confused again

While all the technical details about volume and rate etc are above my head at the moment, I do find it informative to read your conclusion or summary statements. So don't stop your 10-pager debates for us noob's sakes

Snoredog - your theory on CA's is very interesting and I for one would certainly be interested in hearing more from the (medical) community about this line of reasoning.

So when are we going to talk about spontaneous arousals (perhaps causing irregular breathing) ??

[End noob comment and back to our regularly scheduled debate]

echo wrote:So when are we going to talk about spontaneous arousals (perhaps causing irregular breathing) ??

echo wrote:[Pause in highly technical discussion for noob comment]
Hey who's thread is this anyway? Oh sorry Banned! (but we know he's taking a nap anyway)

echo wrote: While all the technical details about volume and rate etc are above my head at the moment, I do find it informative to read your conclusion or summary statements. So don't stop your 10-pager debates for us noob's sakes

They shouldn't be over your head, the volumes discussed are the volumes of air you inhale/exhale that make up a breath. If you count up the number of times you breath per minute that is your BPM (Breaths Per Minute). If you divide your avg. BPM by 60 seconds you come up with the total duration of each breath. If you divide that breath by 2 you have the time alloted for Inhale and the time alloted for exhale or I:E ratio.

If everything is perfect you will inhale the proper amount of oxygen and exhale the proper amount of C02 on each breath.

Since the amount of CO2 retained in your blood controls breathing keeping some in your blood stream is vital. If you do more inhaling than you do exhaling (i.e. I:E ratio) you will have a higher rate of oxygen in your blood and a lower level of C02. Since the level of CO2 controls breathing your body won't like that level getting too low on C02. If it does and it cannot bring that level back up by manipulating how you breathe, it does the only thing it can do, stops you from breathing, hence the Central apnea. The cessation of breathing causes the level of CO2 in the blood to increase, when the level approaches what the brain determines as correct amount spontaneous breathing returns. If you overshoot that balance you are either Hypercapnia or Hypocapnia.

Since the body reacts to events if that respiration gets out of balance (i.e. more oxygen vs CO2) how can you control breathing to increase the level of C02 retained in the blood? One way is to slow your breathing down with each breath. If for example you were breathing at a Respiratory Rate of 20 per minute (RR=BPM), with each exhale you will expel or blow off a certain amount of CO2. If you cut that RR rate in half to 10 BPM, you now have 10 fewer exhales to exhaust CO2, as a result your body retains more CO2. Another way to accomplish that is use a mask that causes you to rebreathe more of your exhaled CO2, that will retain more CO2 and accomplish a similar feat. But carefully controlling your breathing is the best way to accomplish that.

Now when we talk about the peak (inhale volume) and tidal (exhale volume) together they are a breath. The volume found in each is measured in ml (milliliters).

This machine is actually quite simple.

1. Eliminate obstructive events with CPAP (EPAP pressure).
2. Control irregular breathing with Pressure support.
3. Control Centrals seen by slowing RR down with fixed backup settings.

So when you look at one of your breaths; put the time for inhale and exhale together, lets say together they add up to 6 seconds long. So over a minute's time you will take on avg. a breath every 10 seconds. Since each breath is 6 seconds long, put an imaginary separator line between them (3 seconds for inhale|3 second for exhale =6 second breath) which make up the BPM or Respiratory Rate. RR and BPM are the same thing, Respironics screwed the meaning of BPM by calling it backup mode on the SV, but it really is the same thing, number of breaths you take per minute.

Now understand on that 6 second breath (3 sec Inhale/3 sec Exhale) if you shift the center of that breath divider lets say from the center to the left you have 2 seconds for Inhale and 4 seconds for Exhale, breath still 6 seconds long. Doing this shift to the left we take in less oxygen and exhale more CO2. Ratio is now off, move it to the left another second's worth and you have 1 second inhale and 5 seconds exhale, again exhaling even more CO2 but also reducing the amount of oxygen taken in on inhale portion. So now that the ratio is off, your body attempts to compensate for the lack of oxygen (less time for obtaining it) by increasing the number of breaths you take per minute. So you start taking more rapid breaths at that same ratio. If you double up the number of breaths per minute, you turn that 1 second inspiration time into 2 seconds, but you also double the amount of exhalation which causes more CO2 to be blown off at a faster rate.

You might know this ratio of breathing as Hyperventilation. If this type of breathing continues where CO2 levels drops, your brain/body is going to say: "hey I am expelling too much C02 here and due to the shorter inhales I'm not getting enough Oxygen!" since CO2 level controls breathing it stops you from breathing (Central apnea). If the body cannot balance that oxygen/CO2 ratio out it does the only thing it can do it STOPs you from breathing. Unfortunately your O2 oxygen levels also drop which leads to hypoxia as seen on a pulse oximeter.

So I don't see Centrals as a neurological disorder, perfectly natural human body response to a breathing condition. Is your spinal cord cut? No. Do you have a brain disorder? No. Maybe you have slow circulation like from a failing heart and its not getting the blood to the part of the brain fast enough? While that is possible as well as other factors of respiration, in these discussions we assume normal heart and lung function but all of these variables and factors should be considered and/or ruled out in any finding. Other factors that can impact the immediate discussion is COPD, asthma or other disorders.

The particular ratio's quoted above are may/not exactly be what your body uses and examples given is to make it easier to understand, cause I'm dumber than a 5th grader. But you get the idea, I try to explain things so people can understand it. The more people that understand it the less often you have to repeat it.

echo wrote: Snoredog - your theory on CA's is very interesting and I for one would certainly be interested in hearing more from the (medical) community about this line of reasoning.

So when are we going to talk about spontaneous arousals (perhaps causing irregular breathing) ??

[End noob comment and back to our regularly scheduled debate]

dsm wrote:Snoredog

Very good line of thinking and nicely put. I like it !


Just one comment though - where you wrote ...

>>>>
3. Control Centrals seen by slowing RR down with fixed backup settings.

<<<<

Did you actually mean

3. Control Centrals seen by slowing RR down with fixed ratios set for I:E in the backup settings.

DSM

echo wrote:... and then a to SAG... for going and getting me all confused again

Snoredog wrote:If that hypopnea was central, there is NO inspiration, machine won't see that partial inspiration

Snoredog wrote:How does it know it is central? Both events if they occur are displayed the same on the Therapy Flag graph, the only way you know which the machine "seen" is by its response, that being from the report was going to BPM mode seen as a dip on the Patient Triggered Breathing graph.

Snoredog wrote:Respironics wouldn't ask you as part of its titration protocol to input the CPAP pressure that eliminated all obstructive events if it meant otherwise. Since EPAP pressure is static on this machine, you better input the pressure that eliminates all obstructive events. So this means this machine is NOT going to respond to frank obstructive apnea period.

Snoredog wrote:if the machine detects an event resembling an apnea, that apnea has to be either obstructive or central or a combination of both. Since this machine only offers CPAP as baseline support and does NOT have the ability to adjust and respond on the fly therefor machine treats that event as a central by switching to BPM mode.

In any ASV technology, therefore, all of the obstructive events must be manually titrated out. The apneas, absolutely. Theoretically, ASV technology will attack hypopnea, but why spend 4 times the money on something that doesn't do the job as well (because ASV technology never completely matches spontaneous breaths, it always undershoots to avoid the hyperventilation that perpetuates "central dysregulation").

ozij wrote:

Am I right in assuming you really mean "all of the obstructive events must be manually titrated out. The obstructive apneas, absolutely" in that sentence?

Good Lord, 3 posts today, I won't be able to post again until Sunday.

ozij wrote:

Good Lord, 3 posts today, I won't be able to post again until Sunday.

Now how did that saying go ..... "Pray to the Lord, she will provide"....