Pressure Induced Central Apnea - How do you know?

There has been discussion that pressure too high can cause a Pressure Induced Central Apnea. How does one tell if this is occuring? Does it look different on the software?

Gail

Good question, I was wondering the same thing.

I believe a central should show up as a NR or non-responsive apnea, meaning an apnea that does not respond to increasing pressure.

alnhwrd wrote:I believe a central should show up as a NR or non-responsive apnea, meaning an apnea that does not respond to increasing pressure.

"NR" is only in Respironics data, and yes, a central might show up as an NR. But it's also quite likely it would not. A person could have centrals that don't last long enough to score as an NR. I wouldn't want to rely on looking for "NR" on the Encore data to identify centrals. Also, I think it's possible to score an occasional NR without it being a central. A very hard obstructive apnea (especially if the person is using a very low minimum pressure with an autopap) might not respond to the three slight pressure nudges (those go slowly) and get marked as an NR.

As far as I know, the closest any conventional autopaps can come to positively identifying central events as "centrals" are the Puritan Bennett 420E, and the Puritan Bennett/Covidien Sandman Auto. And even then, those machines will notice only a little more than half of all the centrals that could be happening.

Other than those two PB machines, I don't think you'll see "centrals" on the data from any other cpap or autopap, Gail.

More discussions about the central apneas and "pressure induced centrals" (in my opinion, an unnecessary concern) is here:
Links to Central Apnea discussions
viewtopic.php?p=22702
I particularly like the posts by christinequilts and StillAnotherGuest (aka "sleepydave" on another message board) which should reassure most people that an occasional central, or even a handful of them, are no big deal at all:

On page two of this thread: viewtopic.php?t=14225

StillAnotherGuest wrote:The phenomena of pressure-induced central apneas is tossed around far too freely. The vast majority of people do not get centrals because of ultra-therapeutic CPAP levels. BiLevel, Pressure Support (PSV) and Proportional Assist (PAV) Ventilation are another matter. You need some mechanism to drive the pCO2 below the sleeping apneic threshold, and plain old CPAP rarely is able to do that. OK, if you wanna argue that CPAP increases base lung volume (Functional Residual Capacity)(FRC), and since that increases gas exchange, some people can generate centrals that way, fine. But it's not as many as you might think.
SAG

rested gal wrote:...an occasional central, or even a handful of them, are no big deal at all...

Besides, you would need at least 6 handfuls of centrals (approximately an armload) to get reimbursed for a machine designed to attack centrals anyway:

Central sleep apnea (CSA) is defined as:

1. An apnea hypopnea index (AHI) greater than 5; AND
2. Central apneas/hypopneas greater than 50% of the total apneas/hypopneas; AND
3. Central apneas or hypopneas greater than or equal to 5 times per hour; AND
4. Symptoms of either excessive sleepiness or disrupted sleep.

Complex sleep apnea (CompSA) is a form of central apnea specifically identified by the persistence or emergence of central apneas or hypopneas upon exposure to CPAP or an E0470 device when obstructive events have disappeared. These patients have predominately obstructive or mixed apneas during the diagnostic sleep study occurring at greater than or equal to 5 times per hour. With use of a CPAP or E0470, they show a pattern of apneas and hypopneas that meets the definition of CSA described above.

SAG

SAG
I guess the next question becomes, 'how does one distinguish between these ...'

"2. Central apneas/hypopneas greater than 50% of the total apneas/hypopneas;"

DSM

dsm wrote:I guess the next question becomes, 'how does one distinguish between these ...'

"2. Central apneas/hypopneas greater than 50% of the total apneas/hypopneas;"

DSM

You'd go to a sleep lab where they have "effort" belts and all the other necessary sensors -- a la full PSG study. And hope to have a very savvy tech scoring the study.

None of our usual treatment machines are capable of distinguishing between those things, as far as I know.

Central events are explained a bit in this article:
http://www.sleepreviewmag.com/issues/ar ... -04_07.asp

Great article SWS, thanks.