I've never used oxygen. I've nebulized my guys with medication, which is different, but the "oxygen cage" I made would be the same for giving oxygen or nebulizing.
I took a carrier, covered all the windows with plastic wrap, put tape around where the carrier connects top to bottom, put plastic wrap around the front cage door, put weather stripping around the inside of the front door (I used plain white paper towels and taped it to the carrier). I left a little hole in the front of the cate for the end of the nebulizer mouthpiece to poke through after the door gets closed.
What you want is an entrance for the oxygen tube and an exit hole somewhere in the back end of the cage, so I left a little hole in the plastic wrap on the back windows for my exit hole.
You MUST get information from the vet on how much oxygen to give and what the mixture is. I think the oxygen tanks can be adjusted as to what the "potency" of the oxygen is... please, those of you who have used oxygen, post what you know about that. I'm not up on all the ins and outs of using oxygen.
When my Puddy was in the hospital in 2003 they had him in the oxygen tank for 3 days, and they regulated how much oxygen and how potent it is. I know I'm not using the right words to describe that. I now the word isn't potent, but I can't remember what they said. Sorry!
Right now... give Emily ANYTHING she wants to eat. She needs the nutrition to get stronger. The heart can't work properly without the nutrition to "feed" it. Will she eat the dry Friskies if you add some water to it? She might like licking up the juice from the dry food being in it.
If Emily will drink chicken broth, that would be a good thing. Just put a piece of chicken (breast or thigh, no skin - too much fat), in a pot of water and bring it to a boil, then reduce the heat and simmer it till the meat falls off the bones. Use that broth for her, and if she'll eat the meat, that's good too. After it cools you can skim off any fat that collects on the top. Don't add anything, just the chicken and water.
If she won't drink at all, you can syringe water into her, but be very careful with water syringing. Only give her about 1/2cc at a time. Any more than that might make her gag or it might go down the wrong way and into her trachea instead of her esophagus. You don't want her to inhale water into her lungs, so you syringe to the side of her mouth, not down the middle and tiny bits at a time. I do this with my guys, and take a 1cc syringe. The little syringe works for us best with their little mouths. You can get it in the side of their mouths much easier than a 3cc or bigger syringe that they have to open their mouths so wide for. You'll be syringing more, but it's safer. You don't want to use a baby bottle or anything that you have to squeeze to get the water out of, because you can't control how much is coming out and there's too much a chance of them inhaling the fluid.
5cc's equals 1 teaspoon, so if you want to give her 30cc's of water a day, that comes to 6 teaspoons. Don't give her more by mouth than you would if she was getting subQ fluids. You don't want to over hydrate her either. 30 to 50cc's of water a day is a good amount. If she's eating wet food, there's water in the food too, so she'll get some from that. Now, this is just what I've done with my guys, so please ask your vet about how much for Emily. When I was syringing our angel Chris, I gave him 45cc's of food twice a day via syringe and because there was a lot of water in his food, I only syringed an extra a 20cc's of water per day.
For his food, I took a 3oz can of Wellness, added 1 tablespoon of water and mixed it up in my little mini food processor to make it completely smooth enough to syringe. I used one can per day, so I knew he was getting at least 3 oz of food that way, and we also left food out for him in case he wanted to eat on his own. I used Wellness, because it's not the worst food, and it smooshed up really good in the food processor without any lumps.
Please call the vet about how much and how long for the oxygen and what the concentration/potency of the oxygen is supposed to be set at.
I put photos of my "chamber" and SweetPete's oxygen chamber in the groups' photos section. http://groups.yahoo.com/group/feline-heart/photos/album/0/list
Click on the folder "01 Oxygen Chambers"
The one I made is really not pretty, lots of tape all over it, but it works, so I didn't care what it looked like. The one Gina made for SweetPete looks really nice.
I hope this helps. Please let us know how Emily is doing. I'm saying prayers for her today and lighting my healing candle for her.
Carol and Snowball and the gang
Snowball in the garden