mask "vent" question

All masks have a "vent" feature, i understand that u must be able to exhale & u do not want to inhale the air u just exhaled - but:
1. the force of the air comming out of the "vent" on all of my gear (nasal pillows, nasal mask, combo pillows & mask by resmed - always stays the same. So how much air is being forced down my airway and how much is just "vented" off??

The air will of course pass through to the areas of least resistance. Obviously i have some degree of resistence, either due to URAS or collapse of the airway.

I am using a resmed apap set at 15-20 (justed moved up from 13-20). AHIs 5-10.

Thanks in advance. Great lecture from Dr. Gold!

Your machine takes into account the air that is venting, and makes up for it. The volume isn't really all that much compared with a breath.

The mask manufacturer designs the masks to vent so that your exhaled carbon dioxide is expelled and you breath fresh air with every breath. As LinkC stated the xPAP is designed to provide sufficient air (at your pressure) to provide all the air you need and exhaust your expelled air all at the same time.

Cheers

LinkC - thanks for your response. Still new & trying to find my way around the site. I hit reply so hopefully this will work.

OK, thanks. It is just that the air flow out the vent never changes. If i take a deep breath no change. If it take several rapid shallow breaths, no change, it i hold my breath for >10 seconds, no change. Does your equipment act that same way?

Hi,

Yes, My mask acts in a similar way.

The rate that the mask vents is based on your pressure (not how much air you are breathing at any given moment). The little holes that are the vent will pass a set amount of air at a given pressure (the pressure of you CPAP). So, as long as the pressure being provided by the blower is kept constant, the vent rate also remains basically constant. The blower is designed to react and change the volume of air that it supplies to the mask so that the pressure remains constant (thus the vent blows the same amount of air).

The above is a little bit of a simplified explanation, as may xPAPs actually have some sort of pressure relief (e.g.: A-Flex or EPR) that drop the supplied pressure slightly when you start to exhale. This makes it easier to start to exhale. This slight pulsing although measurable and noticeable to the user may not be so easily sensed by "feeling" the air escaping from the vent holes. There are also Bi-Level units that actually set different pressures for inhaling and exhaling.

Your unit is an auto adjusting CPAP so, it will over time change the supplied pressure up and down, within the limits of your therapy, to help eliminate OSA events. This change in supplied pressure will change the vent rate (but your breathing should not).

Hope that helps,

Cheers

eray wrote:All masks have a "vent" feature, i understand that u must be able to exhale & u do not want to inhale the air u just exhaled - but:
1. the force of the air comming out of the "vent" on all of my gear (nasal pillows, nasal mask, combo pillows & mask by resmed - always stays the same. So how much air is being forced down my airway and how much is just "vented" off??

The air will of course pass through to the areas of least resistance. Obviously i have some degree of resistence, either due to URAS or collapse of the airway.

I am using a resmed apap set at 15-20 (justed moved up from 13-20). AHIs 5-10.

Thanks in advance. Great lecture from Dr. Gold!

The whole point of the therapy is to keep your airway from collapsing by keeping pressured air in it.
If you have too many collapses (full or partial) that means your pressure in not high enough. On self adjusting machines, when a collapse is identified, the pressure is raised -- after the fact in order to avoid future collapses. On fixed pressure machines your supposed to sleep at pressure high enoug to keep you from having most events. On no machine is the pressure expected to "blast through" the obstruction.

Thanks Builta & Ocij for your response. It is helpful to know that your machine works the same way. I think it was just confusing to me because i am using an apap machine so i thought there would be adjustments to the pressure, within the range that is set. Have u tried breathing deeply, taking rapid short breaths and/or holding your breath to see it there are any changes in the pressure?

Hi,

yes over the course of several years, five different XPAPs and lots of masks I have experimented with lots of things. If the vent rate changes (and the supplied pressure does not) then it is probably time to have your CPAP blower looked at by the DME.

As I stated earlier, the EPR function of your unit will react to you exhaling by dropping pressure (the extent of the drop is based on the EPR setting and the make and model of the xPAP blower).

CPAP masks are actually rated for the amount of air that they will vent at a given pressure. The information should be printed in the literature that came with your mask. If you cannot find it, you can look at the manufacture's web site for the information. I think that the forum host ( https://www.cpap.com ) use to also list that information in a comparison chart. But, I haven't look for that in years.

Cheers.