Chiming in here since I recently finished and tested my hypoxia 'debreather' device. My first test was yesterday for airflow and CO2 absorption. I exhaled/inhaled five times, not enough to start to feel hypoxic, yet it was enough to test my CO2 'alert system'. The good news is that it worked perfectly, breathing was easy and air flowed well in both directions. My next test will be with a pulse oximeter since I want to know how quickly my O2 drops.
Below are some details, experiences and opinions on the debreather that right2die will be selling (hopefully someday soon) and comparisons to my hypoxia device.
My device is a bi-directional, single circuit, which means exhaled air flows through one tube into the canister that contains CO2 absorbent, next into the counterlung, then the reverse on inhalation. I decided not to replicate the debreather due to complexity, I didn't feel that it needed to be a two circuit system.The debreather system uses a loop that only allows air to flow in one direction using, one way valves and uses ventilator tubing, two CO2 absorbent chambers and one counterlung. They chose this system to eliminate the possibility of CO2 re-entering the lungs which would result in the CO2 alert system being activated and could eventually cause the person to remove their mask due to severe discomfort. In my device the only remaining CO2 would be in the single tube (CPAP) that enters the CO2 absorption chamber. As expected the amount of CO2 that remains in the tube is insignificant and is reduced during each breath since no new oxygen is added to the system. It's important to note that CO2 tolerance varies from person to person.
Now about the mask...I've seen a lot of talk about this, mostly concern which makes sense since it's an important part of the device, probably the most important. That being said any of these devices need completely sealed to prevent leaks. I tested every part of my system, including a couple of masks. I ended up using a high quality CPAP mask, not the mask that they chose for the debreather. The reason is fit, since CPAP masks are designed to be worn during sleep so comfort is very important, as is the seal. The only minor issue is that CPAP is a partially open system, unlike the debreather which needs to completely closed. This meant that I had to modify the mask by closing off all the vent holes, which was easy. The mask is very comfortable and uses a soft silicone for the face seal and a comfortable head strap/harness system. I tested the mask in the same way that the debreather shows, simply by covering the hose connection port and exhaling, ensuring there were no air leaks around the mask. One thing I don't like how the debreather is that it needs to strapped to the body, this was in part due to how they chose to build the mask/tubing system. Since my device only has one tube that is connected to the CPAP mask (with a swivel). The whole unit is strapped to a stable and protected platform which can lay next to me. All my hoses are secured with hose clamps so they can't be pulled apart.
I will report more after my test with the pulse oximeter.
Note: I am happy to respond to questions as I want to help those considering this method, however I am not willing to post photos, plans or give exact details of how I built my device. Please reply here, not using PM. Thanks.
