who invented the use of medical abbreviations?

Theresa, no one person invented the medical abbreviations. They just happened as a particular term or name came to be used often. The abbreviation was easier to write than the entire procedure or medicine.

Example: We use TGIF to say Thank God for Friday. It is quicker and everyone knows what it means.

Here is an interesting site.
http://news.bbc.co.uk/1/hi/health/3159813.stm