I analyzed the free-text field on hospital surveys. A simple keyword search gave me very reliable results on what the patients were complaining about -- they fell into the categories of bad food (food, cafeteria, diet, tasted, stale), dirty rooms (dirty, rat, blood, bathroom), rude staff (rude, ignore, curt), noise (noise, loud, echo, hallway), TV broken (TV, Television, "can't see"). So if the context is narrow enough, even simple searches work.
I agree that more broadly worded questions require more sophistication. I've looked at word combinations and so forth, though I haven't really needed to use them yet in analyzing health care data. We would not trust a computer to parse a full doctor's report, no matter how sophisticated the software; that will require manual inspection, often by multiple people to agree on a consensus interpretation.