Im not really sure, It sounds like a lot of work for a certain type of result.
Is it a result set your refreshing? it sounds like you would be much better using something like AJAX, which im not really fond of but in this situation is probably good.
Instead of triggering from the database you could periodically contact your server to check if what ever it is thats supposed to have happened has happened, and then just use client side script to refresh the page.
Does it have to have a response time better than a minute or something like that? Checking every 10-20 minutes if the action has happened would be fairly easy to do with an ajax framework.
I think your going to have trouble actually sending a response to the client if you already have sent a response... http is a stateless protocol, im not even sure of where to start on that. A problem like yours is probably where all this AJAX stuff started.
Oh, and on a side note the Google Web Toolkit has a framework for running client side applications that do asychronous loading of pages, might be worth having a look at it.