Heart Surgery Scheduled

My Fd has her heart surgery scheduled for the middle of April. But 2 weeks ago, she came down with pneumonia and was hospitalized for 4 days. During that time they found out her blood oxygen levels are alot lower than they should be, even with her heart defect. So now she is on oxygen 24/7, as well as lasix to make sure there is no fluid build up, potassuim solution because the lasix can cause potassium depletion (I guess this is bad), albuteral (breathing treatments) and respiratory therapy. All of this because of a little bit of pneumonia. Its been an interesting couple of weeks. But we got home from the hospital and she started sleeping through the night consistantly (9 or 10 pm til 8 or 9 am), as well as eating more. She ended up loosing weight when she was sick (dropped from 10 pounds, 13 oz to 9 pounds 13 ounces within a month), but put it back on in the week since she's been out of the hospital. But still, there is something severly wrong with a 5 1/2 month old who only weighs 10p13oz. But just as long as she keeps putting on weight before the surgery, I'm not going to worry too much. I understand that it is hard for her to gain weight with this heart condition, so I try to use that as my reason not to worry (but I'm a big worrier, so its hard). Well thanks for listening. Any help anyone has with the AV Canal defect surgery would be very useful. Thanks. AmyGarner