New to CPAP and need some help with mask

[Phil Shiply]

Hi All,

I am glad to find this forum, and I sure would need some help.

I have been using a CPAP machine by Dr. orders and I am not sure what is really happening with my set up.

Now I do understand that the machine will push air into my mask to keep my airway from closing. Is that true?

OK if the above is true, then when I put the mask on, and turn the machine on, it seems to me that most of the air is escaping through a set of small vent holes on the mask. I am not sure if I am getting any air beyond that point.

I feel like there is a vacuum between the mask and my face. Now I do feel at times some leading air between the mask and my face but is that proof that my air way is being propped open enough?

Thanks for any help.

Phil

[Bompa]

Hi All,

I am glad to find this forum, and I sure would need some help.

I have been using a CPAP machine by Dr. orders and I am not sure what is really happening with my set up.

Now I do understand that the machine will push air into my mask to keep my airway from closing. Is that true?

OK if the above is true, then when I put the mask on, and turn the machine on, it seems to me that most of the air is escaping through a set of small vent holes on the mask. I am not sure if I am getting any air beyond that point.

I feel like there is a vacuum between the mask and my face. Now I do feel at times some leading air between the mask and my face but is that proof that my air way is being propped open enough?

Thanks for any help.

Phil

Hi Phil

I will give you the little bit of knowledge that I have but rest assured others with more knowledge will respond.

Yes those vent holes are to expel your exhale breath and any air coming in at that time, if not you would be rebreathing your air.

Secondly in my experience if I felt air coming across my face it meant I had a leak between mask and face.

I am not familiar with the Resperonics system but take a look through this info until someone gets back to you LINK

[trish6hundred]

Hi Phil,
WELCOME! to the forum.!
Hang in there for more answers to your question and best of luck with CPAP therapy.

[cbramsey]

Welcome to the forum!!! We are glad you joined us!!!

I know it seems like all the air is escaping through the vent holes, but it really isn't. Each mask allows a specified amount of air to escape (called the leakage rate).

[RonWessels]

Hi Phil.

Your understanding is close, but not quite correct. The thing that splints open your airway is the pressure, not the airflow. Look at it this way. If you didn't need to breathe, but just needed to keep your airway open, you could use a setup without any intentional leaks, and the machine would pump just enough air to create the required pressure, sort of like filling your car tires. And that pressure would keep the tissues that would otherwise sag and block your airway back in check.

Unfortunately for the engineering, you also need to breathe. Meaning, you need to take some of that air into your lungs when you inhale, and then add back some more air from your lungs when you exhale. Now, without any intentional leaks, the machine could still cope by pumping air into the system when you inhale to keep the pressure up, and sucking it back out when you exhale to keep the pressure down. But this means that you would be constantly breathing back your exhaled air. Not good.

Instead what they do is introduce intentional leaks into the system. This keeps the air flowing, making sure that you always have fresh air to inhale. Now, imagine how it would work if you didn't need to breathe. Just like a car tire with a slow leak, the machine can keep the pressure at the specified level by constantly pumping air in at the same rate as it is leaking out. So now, when you breathe, the machine just has to pump less air when you exhale (because you are supplying some of that leakage flow), and has to pump extra air when you inhale to compensate for what you are inhaling.

That is why unintentional mask leaks are not necessarily a problem. They are just extra leakage that the machine has to compensate for. There are only two requirements on the leak rate. Firstly, obviously the machine has to be capable of pumping the airflow equal to the total leakage rate plus your inhale rate. Secondly, the machine needs to be able to determine when you inhale and exhale. Ignore the machine airflow capability for a moment and imagine a HUGE leak rate. If your breathing is a small fraction of that leak, it is statistically difficult to determine when you are inhaling and exhaling, because the pressure sensors have a certain accuracy and precision. Hence, the leak rate must be small enough that the machine can statistically determine your breathing pattern given real-life sensors and their associated errors.

Does that clear things up for you?

[Paptillian]

As a secondary function, don't the vent holes also prevent suffocation if the power goes out? At least with a full face mask?

[Bompa]

Well said Ron and thanks.

[RonWessels]

As a secondary function, don't the vent holes also prevent suffocation if the power goes out? At least with a full face mask?

I don't believe so, but I don't have a full face mask. My understanding is that there is a separate one-way valve in the mask that make sure that the mask can never experience negative pressure. So, if the machine is off, air is drawn in via this port to allow you to breathe.

Anyone with a full face mask care to chime in with definitive data?

I have actually experienced a power failure while I was sleeping, and I have a nasal mask. I was still able to breathe through my nose, and it actually took me several seconds to realize that the machine was off when I woke up (due to the apnea events, no doubt). I'm not sure if the airflow was going through the leak holes or through the hose and machine.

[PaulaO2]

As a secondary function, don't the vent holes also prevent suffocation if the power goes out? At least with a full face mask?

Full face masks have a special valve for this. Other masks, the same vent hole is sufficient.

[RonWessels]

Other masks, the same vent hole is sufficient.

I believe the reasoning goes that, for nasal masks and nasal pillows, you can always breathe through your mouth as a fail-safe.