Heavy Breathing

No, this isn't about prank phone calls.

I finally have my apnea script from my GP squared away with CPAP.com. I have one last question about CPAP machines on the market.

I find that my current bottom of the line CPAP machine can actually restrict my breathing if its heavy enough. For example, if I just walked my out of shape self up the steps to bed and put on the mask if I need to take a couple of deep breaths, I feel it restricted by the machine. This is not the resistance you feel on exhalation against pressure. I'm actually flow restricted on a heavy inhalation not just exhalation.

I may be the exception. I had a job physical once and the technician measured my lung capacity and it was massive despite not really be that active. Just the way I'm built I guess.

Anyway, I know a lot of people probably don't have this issue. But if anyone has a sense of what I'm talking about and can comment if one of the CPAP lines is better than the other, I'd appreciate it.

I sometimes need to breathe very deeply when I first turn on the machine and lie down. It seems to be the result of stirring myself up, and perhaps holding my breath a little, as I make my final preparations to lie down. It is an uncomfortable feeling, rather like shortness of breath but not exactly. I just breathe as deeply as necessary and I eventually notice that I am not doing it any more because I don't need to.

If the layout of your nightstand and machine, etc. allow it, another approach may be to lie down and catch your breath before you finish seating your mask and turn on your machine.

It would probably help if I were not obese.

john_dozer wrote: I'm actually flow restricted on a heavy inhalation not just exhalation.

It is certainly possible to be flow restricted on inhalations.

Thinking about three possible explanations:

1. Could it be that you have some collapsing of the nose pillows in your Liberty mask that is not allowing normal flow through them? (Assuming you are talking about inhalations through the nose only)

2. What is your ramp setting? Some people report feeling flow restricted when ramp is running from 4 to 6 cm pressure. I am not convinced that this is physical. It may be psychological.

3. Then of course there is the fundamental problem that many of us just have narrow airways. Even when CPAP has them splinted open they are still narrow and provide a level of uncomfortable restriction. This is the case not only when asleep but all day long.

With asthma and heart problems I can get short of breath pretty easily, and for some reason that getting in a good position for sleeping in bed does it for me--it requires a lot of shifting to get things "just right" with my various pillows and tucking in my body parts to avoid the arctic vent blast. I can't be wearing the CPAP at that point--I feel like I don't get enough air for a good, deep breath and it rushes my breathing since the machine dictates the rhythm of inhalations and exhalations. So I know exactly what you mean--and I have lousy tidal volume.

I have learned not to put the mask on right away. I lie down and get comfy, let my breathing get back to normal and THEN I put on my mask. I hold it in my hand so that I hopefully won't fall asleep before remembering to put the mask on--hasn't happened so far, luckily.

john_dozer wrote:
[snip]
I find that my current bottom of the line CPAP machine can actually restrict my breathing if its heavy enough. For example, if I just walked my out of shape self up the steps to bed and put on the mask if I need to take a couple of deep breaths, I feel it restricted by the machine. This is not the resistance you feel on exhalation against pressure. I'm actually flow restricted on a heavy inhalation not just exhalation.

I may be the exception. I had a job physical once and the technician measured my lung capacity and it was massive despite not really be that active. Just the way I'm built I guess.

Anyway, I know a lot of people probably don't have this issue. But if anyone has a sense of what I'm talking about and can comment if one of the CPAP lines is better than the other, I'd appreciate it.

I've noticed the same thing. I, too, have big lungs. Almost 8 liters TVC in my recent pulmonary function test. Used to spend my high school and college summers mostly underwater snorkeling as deep as 50' and wondered at all the guys schlepping all that SCUBA gear. Research indicates that professional divers don't develop higher lung capacity; instead guys with bigger lungs tend to become professional divers. http://www.ncbi.nlm.nih.gov/pmc/article ... 4-0015.pdf However, just because you have big lungs doesn't mean you need to use all that capacity all the time.

When I got my CPAP I learned that I need to consciously moderate my breathing when I first strap on. Maybe it's the psychological effect of knowing you're getting your air through a rather thin tube (ResMed S9 Slimline tube), or maybe it's anticipating breathing against some resistance. However, when I first lie down, I concentrate on moderating my breathing. And as you can see by the attached image my breathing is quite deep and rapid at first while I'm getting comfortable and adjusting the straps (breaths 1-8). Then within a dozen breaths or so, it moderates and assumes the rounded shape characteristic of restful, but awake, breathing. The two periods I combined in the image are only about 2 minutes apart. Shortly after that, the rounded flow profiles assume a sawtooth shape characteristic of sleep. You can see that change beginning in the last "hump" in the lower right-hand corner of the image below.

My wife says I can sleep hanging on a hook. I reply that's just clean living.



As far as equipment goes, all of the CPAP machines function by maintaining a positive pressure in your airway. I don't think it's physically possible for a human to outbreathe a CPAP machine. It might feel like that's what you're doing. I thought that way and, to test the idea, lifted one of the nasal pillows off my nose while breathing in heavily, and found there was still positive pressure at my nose.

I think the sensation is just a feeling that you have to get used to.

I know that feeling quite well.

I have it often when I first put my mask on and the machine is still ramping up. If my breathing is anything above my normal resting breathing rate it feels like I'm trying to suck air through a straw and not getting enough. Luckily I use a nasal pillow mask and when this happens I can just open my mouth for a couple breaths and then all is usually good.

And as noted above it helps if you can train yourself to slow your breathing down. I find that if I start to try to breath too fast I get the same effect. Short, shallow breathing doesn't seem to work too well with my unit. I've trained myself to take longer, slower than normal breaths when I first put on my mask and that seems to help quite a bit. I'd say in normal breathing I'm using about 50-75% of lung capacity on each breath, but when I first put on my mask I'd bet it goes up to somewhere around 90%.

pitrow wrote:I know that feeling quite well.

I have it often when I first put my mask on and the machine is still ramping up. If my breathing is anything above my normal resting breathing rate it feels like I'm trying to suck air through a straw and not getting enough. Luckily I use a nasal pillow mask and when this happens I can just open my mouth for a couple breaths and then all is usually good.

And as noted above it helps if you can train yourself to slow your breathing down. I find that if I start to try to breath too fast I get the same effect. Short, shallow breathing doesn't seem to work too well with my unit. I've trained myself to take longer, slower than normal breaths when I first put on my mask and that seems to help quite a bit. I'd say in normal breathing I'm using about 50-75% of lung capacity on each breath, but when I first put on my mask I'd bet it goes up to somewhere around 90%.

FWIW, I tried slow, deep breathing, which FELT good at the time. But when I saw my data the next morning, I just about screamed like a little girl. When I dropped off to sleep, my machine recorded a dozen or so events all clustered within the first hour or so. AHI went up to 7.5; the worst I've had since starting therapy. So I switched to trying to take slow, shallower breaths and that has worked for me. You can see in the data I posted above how quickly I can make the transition from wakeful breathing to slow, shallower breathing, to sleep.

[Edit: It might be that taking slow shallow breaths also slows heart rate. You can see how quickly pulse drops in my avatar. Oh heck, here's an enlargement of the first hour or so: ]

roster wrote:It is certainly possible to be flow restricted on inhalations.

Thinking about three possible explanations:

1. Could it be that you have some collapsing of the nose pillows in your Liberty mask that is not allowing normal flow through them? (Assuming you are talking about inhalations through the nose only)

2. What is your ramp setting? Some people report feeling flow restricted when ramp is running from 4 to 6 cm pressure. I am not convinced that this is physical. It may be psychological.

3. Then of course there is the fundamental problem that many of us just have narrow airways. Even when CPAP has them splinted open they are still narrow and provide a level of uncomfortable restriction. This is the case not only when asleep but all day long.

For #1, I'm a mouth breather so its not the nasal pillows. I couldn't take deep breaths with my nose with or without the machine.
2. I'm instant on to full pressure. The anticipation that pressure will be increasing nags the back of my mind and makes me focus on the machine. Also the white noise seems to help make me sleepy and the pressure helps with this restriction problem
3. No I can draw a deep breathe without mask & machine pretty easily when using my mouth.

Slartybartfast wrote:As far as equipment goes, all of the CPAP machines function by maintaining a positive pressure in your airway. I don't think it's physically possible for a human to outbreathe a CPAP machine. It might feel like that's what you're doing. I thought that way and, to test the idea, lifted one of the nasal pillows off my nose while breathing in heavily, and found there was still positive pressure at my nose.

I think the sensation is just a feeling that you have to get used to.

Although I have a dumb machine for now, I have a pressure gauge for the CPAP hose. If I breath heavy I draw it to zero on the inhalations. By video taping the gauge, I've caught an apnea event by seeing the needle oscillate with shallow breathing and stop. Then subsequently I had 3 or 4 deep breaths than brought the needle down to zero.

Ok, I saw the "nasal pillows" in your equipment list and somehow thought you were using a nasal pillows mask. If you're a mouth breather, then maybe you CAN outbreathe a CPAP machine. I wonder if the newer machines are quicker to respond than the older ones.

I'm in the process of building a nightstand to contain my CPAP machine and all its paraphernalia. I completed the gauge a while ago and am collecting wood for the nightstand and figuring out how I want some of the pieces to fit together. The idea being so when I wake up in the middle of the night wondering if the thing is still on, I can look at the gauge and know.

Definitely have had this problem before. I now calm down before I attach my "living on Mars breathing apparatus". Not doing this always chokes the machine for me. Also, I suspected my breathing rhythm was being suggested by the machine. I could always hear it winding up for the next inhalation. I felt I had to quickly exhale to be able to catch the next blast. When I had the PR System 1, I found the greatest relief from the C-flex 1 position. I could still however still hear the impellers winding up as the noise travelled up the tubing. I could also hear the machine when the filters would pop out onto the floor with any backpressure. I switched machines and problems went away.
I love the gauge. My doc thought I was crazy when I wanted to borrow his simple manometer. I suspected it ran less efficiently in the middle of the night as I was desperate for more air. Now I just put my hand in front of the air exhaust on the mask to check pressure. My hand quickly calibrated to 11 cm water pressure. I still don't have any more air, but I know the machine is running at the right pressure. But I do like the setup. I think I need a dashboard to make sure things are ok in the middle of the night.