As health insurance companies shift more financial responsibility onto consumers through higher deductibles, co-payments and co-insurance rates, hospital executives are feeling pressure to reveal their most closely-held secret: prices. On Tuesday, Miami Children's Hospital became one of the first in South Florida to give consumers more information — but not exactly the prices — they need to estimate their out-of-pocket costs, an increasingly important factor when deciding where to seek medical care. Hospital executives reduced by 30 percent the theoretical prices on chargemasters, the pricing documents that detail all the related charges a patient runs up for services but not the amounts most people actually pay.