The Embase database has a powerful tool that allows you to build a search using keywords from a PICO question.
To set up a search using your PICO question, click on the PICO link under Quick Search.
You will have the option of typing in keywords that represent your population, intervention, comparison, and outcome. When you type in these keywords into each box, Embase will suggest the standard Emtree term (Embase's equivalent of a MeSH Heading) and will automatically generate related keywords and synonyms to help you maximize your search results.
This can be a particularly useful tool if you are doing research for a systematic review.