This one can be complicated. But, generally speaking, if the person who has received the chart, it will be in their deleted items until the deleted items is emptied. And, once they delete it and it is in their deleted items, then the sender can't retrieve it. It won't be in their outbox. Unless, the recipient retrieves it, then it will. You can either memorize all this complete with when changes will be kept or lost or kinda do what Wendell is suggesting. Which in this situation, stop, take a deep breath, check his inbox, outbox, deleted items (where it should be). And, check the sender's (your) outbox and deleted items.
I am not quite sure how this happened, but when you pull a chart from your inbox, you have the option of deleteing it from your inbox then so when you sign it off, it is no longer in your inbox (which is what I do) or you can choose to not delete it so that after you sign it off or forward or whatever, it is in your inbox. I NEVER let a medical student or resident select "delete from inbox," then everything is pristine and safe and just like it was when it was forwarded to me. Sure, I have to go back and delete it, but I would rather do that.
Note: In version nine, you will have the option of one of these being set by default or at least having delete from inbox being set by default. This, I believe, will be at the user level.