If you will be placing an IV during the procedure you will want to make sure you select that when you initially start your case. If you are in the patients anesthesia record you will go to "case info" and under "will you be using an IV on this case" select "yes." See image below.

Also, if you originally thought you would not need to use an IV on your sedation case and during the procedure you end up placing one you can go back and follow the above steps to add it into your final record.