Breathing Oxygen: Is there a "Proper" Technique?

[D_C71]

Hello All. New member, First Post...

In September 2007, I completed the CAMI Physiological Training (Altitude Chamber) at Beale AFB, California (received my little blue card for completion.) It was an interesting experience and I got to stay in base housing, for like $35 for the night before the training.

It was also interesting to be at the home-base of the U2 and former SR71 spy planes, see the pressure-suits, crews, etc.

Everything basically went Ok, except that I found it really, really hard to get comfortable breathing through the face-mask. Seemed like all I could do, or really concentrate on, was each-and-every breath.

It was like breathing through a straw, with your nose pinched-off. Everyone else in the chamber seemed to be doing just fine and relaxed. I was using the Pressure-Demand (forces air into your lungs when you flip the console switch) just to get by. Every single breath was an event (required thought and effort.)

Didn't seem right; Shouldn't the "Normal" setting have been enough?

After the chamber ride, I asked the AF crew there if they could check/test my mask and equipment. They said it checked out as Ok.

Yesterday (when I joined) I read Tristar (Tristan's) CAMI post, and saw this quote in one of her replies:

Kent, I am unfamiliar with your oxygen system, but the system we used had three settings; emergency, normal, and off.

I had trouble with the normal system, since I encountered the same thing you did. I had to breath really hard to inhale much oxygen, so I could see how it would impede concentration.

However, the emergency setting forces oxygen into your lungs which you will also hear in some of the altitude chamber videos by the low freq. rumbling noise. Although, noisy, it's much easier to breath.

Tristar

At Beale AFB, (as best I recall) they never encouraged us to use the "Emergency" or "Pressure-Demand" button (except to try it out/experience it,) but not use it frequently or in place of the "Normal" setting.I read in my Jeppesen Instrument/Commercial Textbook, that with regard to the Pressure-Demand system (for use above 40,000 feet,):

"Because the oxygen is delivered at a positive pressure, you need to receive special training to develop proper respiration techniques before using this system."

All this had me wondering...., was my difficulty in breathing (more or less) just in my mind?

Would there have been sufficient Oxygen delivered in the "Normal" mode, but due to the lower VOLUME of gas delivered to the mask ("Oxygen Only," versus normal "Air" at roughly 80% Nitrogen and around 20% Oxygen) the cause of the difficulty I experienced?

Perhaps I was just having a bad day breathing? At the time, it really had me concerned and (as you can probably tell) still does.

Had me also wondering, is there any common, civilian training available to get someone comfortable and/or educated in the proper use of the mask, pressure-type mask system?

Does anyone know about this or have any advice? As I said, it still has me concerned.

Thanks.
D_C

 

[bbchien]

The Scott oxygen system used by CAMI (and used by the USN at least back-in-the-day) has a max inspiratory flow rate of 30 l/sec. If you are in the least panicky, you will top 30 L /sec for about 80 msec in the middle of inspiration. You need to be Cool Hand Luke to not stress when breathing.

If you stress, and exceed even mometarily the 30L/sec draw, you will hit a wall, and that's very upsetting.

So what you think may well have been true. Do you scuba? It can happen there, too.

 

[Everskyward]

Does anyone know about this or have any advice? As I said, it still has me concerned.

All I can say is, the first time I used a diluter/demand mask on "normal" I wasn't getting enough O2 because I wasn't inhaling deeply enough to trigger the valve. Once I figured this out or someone told me, I don't remember which, I never had problems with it again, and I was in a situation where I had to wear the thing for hours at time. I'm not sure from your description if this was your problem, though.

 

[Tristar]

I can understand where you got the impression. When the mask was set on normal, I was calm but the lack of oxygen made me feel claustrophobic. Due to another reason not related to me, I ended up changing seats and found that the mask was easier to breath. I'm not sure if it was the valve or the fact I got used to it. The emergency setting was very nice because I had absolutely no problem breathing, but as stated, thats because it shoves oxygen down your throat. Both systems can be distracting, but if you're easily distracted, having to wear a mask can be rough enough. CAMI is a good experience but being above 35 and having to wear it for hours on end while flying a plane would be a better realistic challenge.

If you have a PPC, Cami is the closest I know to civilian training with masks and high altitude.

 

[D_C71]

Thank You. Appreciate the replies.

Bruce, I think that may have been it. I was expecting to get (basically) all the Oxygen I could want/use, and when that didn't seem to happen, my first thought was that there was something wrong with my equipment (defective.)

That probably panicked me a bit and made things even worse (even greater Oxygen consumption.)

INverted, I can assure you that I was inhaling as vigorously as I possibly could, and don't believe that the Altitude-Chamber system operated with that same type of low-pressure-sensing oxygen release valve, but certainly appreciate the thought and your reply.

Tristan, appreciate your reply and earlier post too. Yes, I experienced feelings similar to this from your reply:

I was calm but the lack of oxygen made me feel claustrophobic.

I have my Commercial Multi, but really anyone (non-pilots, skydivers, etc) can apply for/receive the CAMI training. Still, I wonder if there is any other oxygen-system training out there for civilians (like perhaps at ATP, Embry-Riddle, etc?) or somewhere else?

As it turns out, there is an Aviation Life Support Equipment manufacturer (GENTEX,) just a few miles from where I live, that offers Training, but it is training meant for the people that train / test pilots (Certified Trainers) and not for Pilots themselves (see link.) http://www.gentexcorp.com/assets/gentex/Respiratory/brochure_GWB-0020A_refrshTrain.pdf

In any event, it is good to hear from others about this subject. It was my first experience with a pressure-type oxygen mask system and I had no idea what to expect 'til I got in there.

Appreciate the replies and information.

Thanks Again,
D_C

 

[Capt. Geoffrey Thorpe]

The Scott oxygen system used by CAMI (and used by the USN at least back-in-the-day) has a max inspiratory flow rate of 30 l/sec. If you are in the least panicky, you will top 30 L /sec for about 80 msec in the middle of inspiration. You need to be Cool Hand Luke to not stress when breathing.

If you stress, and exceed even mometarily the 30L/sec draw, you will hit a wall, and that's very upsetting.

So what you think may well have been true. Do you scuba? It can happen there, too.

I haven't had the high altitude training, but I have run into a similar situation during fire-fighting training with an air pack. A little bit of "anxiety" tends to push your breathing rate up, which seems to be able to overwhelm the hardware, which tends to lead to panic which definitely overwhelms the air supply. The feeling is that the tank must be empty and you aren't able to get air.

 

[poadeleted20]

Given that it's highly unlikely that you will run into a pressure-demand system in a civilian application, I don't see this as a concern. In light planes, about all you'll run into will be a continuous flow mask or cannula. For the mask, just breathe normally. For the cannula, listen to Miyagi -- "Breathe in through nose, out the mouth. ... Don't forget to breathe, very important."

 

[D_C71]

Appreciate the new replies and information. Thank You both.

Though I won't likely encounter more sophisticated oxygen delivery systems in small general-aviation aircraft, if I wind up piloting business jets or jet airliners, aren't many of these aircraft equipped with pressure-demand, quick-donning masks?

I found this explanation of equipment requirements for a Cessna Model 750 (Citation X):

Decompression above the 37,000-foot limit depicted in Figure 4 approaches the physiological limits of the average person; therefore, every effort must be made to provide the pilots with adequate oxygen equipment to withstand these severe decompressions.

Reducing the time interval between pressurization failure and the time the pilots receive oxygen will provide a safety margin against being incapacitated and can be accomplished by the use of mask-mounted regulators.

This special condition therefore requires pressure demand masks with mask-mounted regulators for the flightcrew. This combination of equipment will provide the best practical protection for the failures covered by the special conditions and for improbable failures not covered by the special conditions, provided the cabin altitude is limited.

 

[poadeleted20]

Though I won't likely encounter more sophisticated oxygen delivery systems in small general-aviation aircraft, if I wind up piloting business jets or jet airliners, aren't many of these aircraft equipped with pressure-demand, quick-donning masks?

If you run into that, you should be trained on that as part of your high altitude endorsement training. However, in the military, we were taught to work to breath normally. That takes some getting used to, as the system will try to blow you up like a balloon when you start to inhale.

 

[D_C71]

Thanks Ron. Yes, I got a sense of that (being blown up like a balloon) when I flipped the switch on the console.

D_C