Adjusting Leak Rate to increase CO2

The actual problem is low O2, not high CO2, but they are linked.

Indeed. I work with liquid nitrogen and nitrogen and argon purged-clean areas. These are deadly beyond belief. The problem is that most people are not aware of the danger. The common thought is that since you can hold your breath for a couple of minutes, getting a lung or two full or pure N2 should not be an issue. After all, N2 is 78% of the air we breath and is not toxic. The are dead wrong. Breathing pure nitrogen will cause you to pass out in seconds without warning. Death occurs in minutes. You can hold your breath for a coupld of minute only because of the oxygen reserve in your lungs. The oxygen in your blood does not last long at all. I have seen a person pass out from inhaling a couple of Helium filled ballons and it scared the hell out of me.

Breathing stale air is not as deadly as breahting pure N2. In a normal person, the higher CO2 level will trigger increased respiratory rate and cause a panic reflex. If you are re-breathing air, this reflex occurs long before O2 levels drop to a problem level. For a normal person, I don't actually know if it is the CO2 or low O2 that will kill you if you continue to rebreath air. My guess would be the low O2. Actual CO2 poisoning usualluy occur when someone is being given oxygen and their lungs cannot properly remove the CO2.

CO poisoning is a totally different mechanism that also occurs without warning and is quite deadly.

I am also familiar with shallow water drowning among experienced swimmer, though thankfully I do not have any first-hand knowledge. This is case where you CO2 reflex is suppressed by hyperventalating and becoming hypocapnic.

I have noticed that my full face mask has an anti-rebreathihg valve but the nasal masks do not.

Why would you purchase a nasal aire with all the improvements to nasal pillows the past 10 years? The exhalation ports on the nasal aire are exactly why diffuser type exhalation ports were designed; to be quieter and to not blow on patient or bed partner. While you are modifying the mask, you may as well figure out wha to do with seam in the nasal flanges before you develop a callus in your nose from them rubbing.

Thanks for sharing.

I would not block the vents on a mask under any circumstances! This is much too dangerous.
As someone said, with all the new masks out there with great fit and ventilation, why would you stick with that old mask and take potentially serious risks?

Hawthorne wrote:I would not block the vents on a mask under any circumstances! This is much too dangerous.
As someone said, with all the new masks out there with great fit and ventilation, why would you stick with that old mask and take potentially serious risks?

He's trying to increase his CO2 level because it may help with increasing his respiratory drive. (How hard your brain is trying to breathe.) Google EERS (enhanced expiratory rebreathing space). It's a legitimate experimental type of therapy.

I'm really concerned about discussing do it yourself EERS/CO2 enhancement. I"m worried someone will get it wrong and kill themselves.

To be very clear about all this, I do not advocate that anyone try DYI EERS. First, most folks with sleep apnea will not benefit from it. If you have an impaired respiratory system, the experiments that I am doing could be quite dangerous. Even if you are healthy, the experiments that I am doing should be done under medical supervision with close monitoring. I realize that this is a CPAP forum and not a general apnea forum and posting about DIY EERS is both out of context and makes some people uncomfortable. If this entire thread is deleted, I will not bring it up again. However, I do seem to have a condition that benefits from EERS; I am not sure how common my condition is. I think that for some people with central apneas, EERS may be worth exploring.

My leak rate dropped dramatically last night from around 20 l/minute to 4 l/minute for about 5 minutes last night. I am not sure why this happened. That is an unacceptably low level and I will not be using the setup again until I figure out why the leak rate dropped and make corrections. It is interesting what happened as a result of the low leak rate. I do not know if I woke up after the five minutes and cleared whatever it was that was blocking the vent holes. My respiration rate did not really change during the event and stayed 12 BPM. My pulse rate only changed slightly, from maybe 78 BPM to 80 BPM (a little fast, but not out of my normal range). My tidal volume jumped dramatically, from about 800ml to over 1600ml which doubled my minute vent rate as well. There was no change in my spO2 level.

My stats for the last several nights have been somewhat disappointing. It appears that those first two nights may have been an anomaly. I am having other issues with my set up including a LOT of water buildup in the hoses. I am done with the EERS experiments for now. I will probably go back to the nuance pro mask that has some 'built-in' EERS. My apnea is reasonably well controlled without EERS, and as I said, I have not sustained the dramatic improvements I got the first two nights. I don't believe I will pursue medically supervised EERS either. I may change my mind at some point in the future.

It would be really cool to have a machine like an ASV machine that constantly adjusted EERS volume or injected CO2 into the breathing stream to keep respiration at a target mark. I don't think I am going to try to build one.

As far as the negative comments on the Nasal Aire II, the vent port design and the headgear leave a lot of room for improvement, but I actually like the prong better than the nasal cushion interface. I have difficulties keeping the nasal cushions in place and they make my nose a little sore. I may try a different nasal cushion mask (swift maybe?). I wish there were more choices with prong-type masks. WIth a little tweaking, the Nasal Aire would be very nice for me.

cnaumann wrote:To be very clear about all this, I do not advocate that anyone try DYI EERS. First, most folks with sleep apnea will not benefit from it. If you have an impaired respiratory system, the experiments that I am doing could be quite dangerous. Even if you are healthy, the experiments that I am doing should be done under medical supervision with close monitoring. I realize that this is a CPAP forum and not a general apnea forum and posting about DIY EERS is both out of context and makes some people uncomfortable. If this entire thread is deleted, I will not bring it up again. However, I do seem to have a condition that benefits from EERS; I am not sure how common my condition is. I think that for some people with central apneas, EERS may be worth exploring.

Actually, I was forced into experimenting because when I switched from the CPAP to Bi-PAP having developed central apnea. I was waking up suffocating. My O2 was fine but I was gasping for breath, and my breath rate had steadily increased over several hours from 15 to 23. Everyone told me it was impossible for me to be rebreathing, so I did my own experiment. Simply see how much air comes out the intake when I exhale. That much air must go down the tube.

I have central apnea that developed after I started using the CPAP for obstructive. So I figure the CPAP was training me not to breath. I have since eliminated the central events by tuning the CO2 rebreathing. I also have central while awake, so I wear an oximeter with alarm. It is my goal to slowly reduce the CO2 level in the CPAP to see if I can train to breathe at a lower trigger level.

I have been off O2 during the day for a week now, and no longer set off the alarm set at 88% while awake.

I will begin reducing O2 injection on the CPAP next week. I have found that my CPAP needs change nightly depending on how tired I am, etc. So I wear it awake for fifteen minutes to adjust it. My goal is to have no mechanical intervention by using the CO2 level to trigger breathing. I have accomplished that for a week now.

In my case, the nazal pillows created too much CO2, so I am not blocking it, but have punched holes in it. As I increase the leak, more of my breath can escape and reduce the amount of rebreathing at the same pressure. When I want to increase CO2, I adjust the pressure down.

To me this is just a one axis robot, and I am tweaking the PID loop. I make the adjustments to treat my central apnea. Your skill set may differ, so you may not wish to try this at home. Get a room at the Ramada Seriously though, this is not medical advice. It is merely a report of the stupid things I do to myself.

To me this is just a one axis robot, and I am tweaking the PID loop.

I love the analogy. I tend to think of it in terms of tweaking the noise gain to compensate feedback amplifiers myself.

Everyone told me it was impossible for me to be rebreathing, so I did my own experiment. Simply see how much air comes out the intake when I exhale. That much air must go down the tube.

I am not exactly sure what you did here, but part of this is directly reported by data-capable machines. Your minute vent rate is the amount of air going in and out of your lungs, the total leak rate is the total amount of air going through the tube.

Some masks (may be all full face masks?) have an anti-rebreathing valve on them. My Airfit F10 has one as well as vent holes. Other masks like the nasal-pillow Nuance Pro only have vent holes so that when you breath out, some of your breath will go down the tube. The mask should have a high enough total leak rate so that most of this used air gets flushed out quickly.

I have given up on home EERS. I have to have my machine to monitor it anyway, and the results are not any better than what I am getting just using my Nuance Pro mask with a low EPAP.

cnaumann wrote:Some masks (may be all full face masks?) have an anti-rebreathing valve on them. My Airfit F10 has one as well as vent holes.

no mask, to my knowledge, has an anti-rebreathing valve, the f10 certainly doesn't.

it has an anti-asphixiation valve, which is a horse of an entirely different color.

the AA valve closes when the tube is under pressure, it does NOT prevent air from going back down the tube, it's purpose is to open if the machine shuts off, thereby increasing the vent area so that you can get enough fresh air to avoid asphyxiation.

My nasal pillows have no valves. I like them because with my facial hair they provide the best seal in order to have consistent results.

I am tuning nearly blind. I am unable to read the CPAP data or the Oximeter data yet. None of the software runs on my Win 7 64-bit computer.

The simple test is that I can blow out a candle at the intake port by exhaling... Absolutely don't do this at home since you risk pulling the flame into your filter. This tells me in fact breath goes down the tube. I don't need numbers to tune it.

By opening more holes in the pillows, the CPAP will maintain the same pressure with a higher flow rate, reducing the amount of CO2 in the tube available for re-breathing. The same effect can be obtained by increasing the minimum pressure, but this requires more effort to breathe.

With increased CO2 you have more breathing effort. BPMs increase and volume increases. I use this feedback to tune it before I go to sleep. The fact that BPM's do not increase with time, and heart rate is normal resting heart rate, and oximeter alarms aren't going off tells me I am on the right track.

My plan is to continue to lower the pressure and O2 injection and increase the flow rate and attempt to wean myself off the gear all together.
The original Obstructive Apnea was positional (on back) and due to mouth breathing. The nasal pillows have allowed me to learn how to breathe through my nose. The fact that I am off all equipment during the day makes me hopeful I can accomplish it at night as well.

It is a serious matter for me because I had hypoxia-induced atrial fibrillation. I have 66% transfer of O2 in the lungs, and with everything else, the Blood Pressure medicine was not allowing my heart rate to increase and deliver the O2 I needed. I go hiking in the mountains with pack goats, and I do not wish to carry a rack of batteries with me to run all the gear they say I need.

pig wrote:I am tuning nearly blind. I am unable to read the CPAP data or the Oximeter data yet. None of the software runs on my Win 7 64-bit computer.

what oximeter and cpap do you have?

CMS50F Software and drivers install OK. Then device is not recognized. Downloaded alternate drivers from the Manufacturer, still no go
Respironics REMstar Auto 550P I can move files from the memory stick to the Drive, but the software doesn't see it.

no mask, to my knowledge, has an anti-rebreathing valve, the f10 certainly doesn't.

it has an anti-asphixiation valve, which is a horse of an entirely different color.

You are completely correct. The valve flap covers the hose opening in the 'relaxed' state, but it does not seal against anything. That was my confusion. It does not obstruct airflow back into the hose.

pig wrote:CMS50F Software and drivers install OK. Then device is not recognized. Downloaded alternate drivers from the Manufacturer, still no go
Respironics REMstar Auto 550P I can move files from the memory stick to the Drive, but the software doesn't see it.

both the cms50F old, and new versions are supported by sleepyhead, as is the prs1 550.

sleepyhead runs quite happily on win7 32 and 64bit.

with the older F model make sure that you're using the cable that came with it, it may LOOK like a usb cable, but it's not. it's a serial to usb converter cable.

The nice thing about Sleepyhead is that it is very adjustable. The font and graph size can be adjusted for your vision.