I work in this industry (sad to say), but you should be able to call your insurance provider to see what it is. Basically he is saying that if you meet that out of pocket that is as much as they can hit you for since you have valid insurance; well insurance companies are crooked so they will try to deny services so they get around this, but there is a max. At that point you have to appeal the payment and usually if you fight them enough they will pay. You should also look into setting up a flex spending account too because then medical expenses are not taxed and can save you a lot of money if the surgery is huge. Normally though you should only have to pay that $2500 deductible if you stay in network so the surgery is probably going to be covered more than you think if it is not a pre-existing condition that your insurance has flagged you with or non-covered!
Last you may want to see if your daughter would qualify for Medicare if this is a life disability. Most people think Medicare is only for people over 65 years old, but it is also for disability and ESRD (end stage renal disorder; kidney failure). May be worth applying...