I went in today to get fitted for the test package, and was wondering how certain things work. There’s an electronic box with four things attached to it: a sensor attached to my finger (making it hard to type right now), a tube to stick up my nose when I go to bed, and two electrode bands around my chest and stomach. The finger sensor apparently measures oxygen density in the blood by measuring light absorbtion with a red diode, and the nose tube measures air flow and maybe also oxygen density, but I’m not sure about the electrodes. The tecnician measured me twice, cut two lengths of elastic with thin copper wire woven in, and attached buckles with wires that plug into the box, Then he fastened the bands around my body over my T-shirt, tested the equipment, and sent me on my way. I asked what all the stuff did, but he forgot to explain everything. So what do these bands measure? How do they work without directly touching my skin?
You’re right about the finger sensor. The tube in your nose measures exhaled CO2. The bands around your chest measure the expansion if your chest during a breathing cycle, so it measures the depth of your respiration the data will be combined on a chart that will show, for example, as your O2 Saturation goes down (finger) your CO2 goes up (nose tube) and your chest expansion ceases or decreases dramaticly.
Good luck and breath and sleep well. 
That would be expansion of and there should be a break after “respiration”
Sorry about all the typos, I’m going to sleep now too.
I didn’t sleep very well last night with all the junk taped and strapped on. I felt like a Borg drone or something. Hopefully the recorder got enough good data so I don’t have to do the damn test again.
Enjoy this modern technology. When I got my apnea test done, I had to sleep at the hospital, with electrodes GLUED to my SCALP. I would have killed to get bands around my chest instead, especially after the tech started pulling the damn things off the next morning. OUCH!
The take-home apnea test is just a preliminary. If it shows signs of apnea, they’ll have you into the sleep lab overnight. If that shows signs of apnea, they’ll probably fit you with a CPAP. If that doesn’t work, they might recommend surgery.