DON'T PANIC!!! She's obviously feeling good and healing well!
We've been monitoring Skyler's Coumadin levels for 13 years. You will do fine. From experience, the worst thing you can do is prevent your child from doing exercise.
I have a couple things to add to the conversation i terms of pointers:
1) metabolism DOES affect INR levels. Skyler's activity levels have increased drastically since having his valves replaced, and his coumadin levels have gone up (by 2mg/day). However, it's not a HUGE variation like with vitamin K, so as long as her activity level is relatively consistent, then don't worry about it. What I mean by this is that if she suddenly goes out and plays 5 soccer games in a tournament in one day, there may be a slight effect on INR. However, going to play one soccer game, or even two, will not make it fluctuate that much. If she consistently plays 5 soccer games each day, then there will likely be a change in her INR and therefore coumadin levels. Just like vitamin K, dose the activity level, not adjust the activity to fity the dose.
2) a level 1 on the "sticker" isn't enough at all. We use 3.5-4.5 for Skyler and still have to "milk" it. The location of the prick is also important. If you are pricking on the pad of the finger there will be a lot less blood because the skin is much thicker. You should be pricking on the side of the finger - halfway between the nail and the pad, and not on the finger tip either (does tha make sense?) It really helps us to prick, then start at the middle of the hand, and "milk" down the finger to get a good drop for our machine (Coaguchek XS). Consider getting capillary tubes and a tiny little squeegy to transfer the blood. It's much easier than maneuvering a child's finger.
3) Activity level for a 7yo post heart surgery is usually FINE. Hannah (hannahsmom ID here) was back swimming and doing gymnastics at 6 weeks. Skyler went swimming 7 weeks post surgery and swam better than he ever had in his life, with better breath control and circulation (yes, treading water and front crawl which is way more stress than playing catch). I would try not to limit her activity, just ensure she isn't over-doing it and that she is getting enough rest to heal. If she is really exhausted, then let her sleep in and miss the morning at school. I quizzed the physio person at the hospital about physio and exercise levels for Skyler and she was adamant that for kids, unless they are extremely strong willed, that letting them go to their limits is the best rehab. Kids naturally test boundaries and will stop if there is too much pain. Limits on how much she can lift make sense, but unlike adults, kids heal REALLY fast. In february (8wks post surgery), Skyler cardiologist gave him the go ahead to lift what he felt capable of, setting his own limits. So at 7 weeks, I woudn't worry too much.
4) We've found that a general vitamin supplement with vitamin K in it has actually helped maintain a consistent INR level. You can read various articles (thegymguy put a bunch together in a post) about taht and it really works. We have very little fluctuation in INR for Skyler unless something wacky is going on like he takes the wrong dose for a week at his mom's house!
5) we get that message on the Coaguchek monitor when you dno't put the chip in place, or you have the wrong chip for the strips. Double check that the chip (it comes in the bottle with the strips) is in the machine correctly, and try again.
6) Skyler's INR levels were very low for 3 months post surgery (in the 1.3-1.8 range) without any bridging. Although at higher risk, children are the most resilient at dealing with blood clots. Short term decreases should not be much of an issue (a couple days to a week). Has her INR stabilized post surgery? Have you maintained that dose?
Lastly, what has hindered Skyler the most has been being "babied", and forced to slow down. It hasn't helped his self confidence, his gumption, or his attitude. So, unless the cardiologist specifically said that she shouldn't do particular activities right now, then let her try things. She will stop if it becomes painful.
When's her next appointment? Please keep us updated on her progress. Have you noticed any improvement since her surgery?
If you have any questions feel free to PM me!
