Link for Zonk

[SleepyWabbit]

I've used it a lot since my memory stinks.

me too, bud.

QAL

Is it a memory leak?

ba dum tsh

[PaytonA]

Memory leak is a definite problem for me. Does anyone know how it is calculated?

[pholynyk]

Just guessing... neurons per day? or maybe killo-neurons per month?

I can't remember...

[PaytonA]

That sounds like it might be the leakage units but how is it calculated?? Or are we getting into Way Off Topic stuff here?

[SleepyWabbit]

It looks like there are studies that certain sections of the brain that control memory actually shrink over time due to loss of oxygen associated with sleep apnea.

Maybe if we could figure out a way to measure the weight/size of our white matter, grey matter and mammillary bodies (also a part of the brain) over time. The question is, if my brain is shrinking, where is the matter leaking? Is that why I keep having a runny nose? At least now I have an excuse for my faulty memory. I'm looking forward to getting my xPAP and starting therapy, and maybe improving my memory.

Some interesting links I came across out of curiosity:
http://www.ncbi.nlm.nih.gov/pubmed/18486338
http://www.ncbi.nlm.nih.gov/pubmed/20861295
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3242693/
http://news.health.com/2008/06/11/sleep-...in-memory/
http://www.sciencedaily.com/releases/201...135438.htm

And to think this started off as a joke...
Now if only we had that home MRI scanner to go with the openEEG project

//sorry if I hijacked the thread and took it way off in left field

[PaytonA]

Here, from Resmed, is part of the reason that designed vent rate is not used for unintentional leak calculations. The following is a quote from just above the Vent Rate vs Mask Pressure chart of the F10 user guide.

The mask contains passive venting to protect
against rebreathing. As a result of manufacturing
variations, the vent flow rate may vary.

Variations in vent flow occur as a result of use also. Mucous can get in the vent and harden changing the vent area and flow. Even water can, as evidenced by the reduction in flow of the P10 masks that can occur from trapped water. There are several threads on this in this forum.

The mask type designation is used to adjust for pressure drop due to the different mask types not to calculate unintentional leak rates.

Best Regards,

PaytonA

[zonk]

These two threads ought be combined together
http://www.apneaboard.com/forums/Thread-...#pid119570

[vsheline]

Leak: An estimate of the total flow of air escaping due to mouth and mask leaks. It is derived by analyzing the inspiratory and expiratory airflows, together with the expected mask vent flows. High or changing leak rates may affect the accuracy of other measurements.

...

The statement, "It is derived by analyzing the inspiratory and expiratory airflows, together with the expected mask vent flows." seems bogus to me. If you use the expected vent rate and the actual flow rate (measured) that would be all of the data you would need to do a quick subtraction to calculate the leak rate. You would not need inspiratory and expiratory airflows.

Hi PaytonA,

Granting that the methods ResMed now uses for estimating the intentional vent rate may have evolved away from the simple explanation given in the quote, I would like to address only the intended meaning of the quote from ResMed:

In the quote "the inspiratory and expiratory airflows" referred, I think, to the total airflows in the circuit (humidifier, hoses, etc) between the machine and the mask.

The expected vent rate would have been a function of the pressure reaching the mask. The machines measure the pressure at the machine, and they would have needed to calculate/estimate the pressure at the mask.

Airflows in the circuit (and therefore the pressure lost across the circuit before reaching the mask) are larger during inspiration than during expiration.

So, during inspiration the inspiratory airflows were used to calculate the pressure reaching the mask, and during expiration the expiratory airflows were used.