The feat Medical Expert says (in part)
You can use the Medicine skill in conjunction with a medpatch or sprayflesh to treat deadly wounds as a full action.
The Treat Deadly Wounds use of Medicine Skill says
You can use Medicine to restore Hit Points to a living, wounded creature. This takes 1 minute, and the DC is based on the medical equipment used.
The Basic and Advanced Medkits both explicitly list the ability to use them to Treat Deadly Wounds, and lists a DC of 20 and 25, respectively. A Medpatch cannot normally Treat Deadly Wounds, and so does not list a DC. Sprayflesh allows the treatment of Deadly Wounds an extra time a day, and lists DC25 for that.
Can a Medpatch alone, without a Medical Kit, be used to Treat Deadly Wounds by a character with the Medical Expert feat? If so, what is the DC? How about Sprayflesh?
Best Answer
Yes, it does require a medkit (or medlab)
Here is what Medical Expert says:
What this feat does is to allow you to make a Treat Deadly Wounds action (from Medicine skill) as a full-round action instead of taking 10 rounds (1 minute), as it normally would. The medpatch or sprayflesh is not being used here for their original purpose, they are accelerating the process instead. The reason for this is not because the Medicine skill requires a medkit, but that it requires a tool that allows you to Treat Deadly Wounds, which neither the medpatch nor sprayflesh do.
The proper tool is still required and you still use the tool's DC for this check. Example: For a Basic Medkit (DC 25), and for an Advanced Medkit (DC 20). While both Medical Lab and Medical Bay function as an Advanced Medkit and thus have the same DC.
Do note that the original effect of the medpatch/sprayflesh will not work when using the item to enhance the time, which means you do not gain the +10 to Medicine checks from a medpatch. If you have the time for it, it is better to use the medpatch to gain the +10 bonus and take a minute using a medkit.
But this doesn't mean you cannot use an extra medpatch to gain that +10 bonus on your Medicine check, effectively using two medpatches if that's the case. Or use a sprayflesh to gain the benefits of Medical Expert and a medpatch to gain +10 on the check.
The feat also allows you to make a Long-Term Care action (also from Medicine) simply with a medkit (instead of a medical lab or medical bay), simply by taking a DC 30 check. Here you could also use a medpatch to obtain it's +10 bonus on the check though, as this is a separate effect.
One thing to consider is the fact that if they did say "with a medkit, medilab or medical bay", then they would be backfiring themselves on future suplements, they would have to add a note about medical expert every time they write up a new feat, tool or ability that allows you to Treat Deadly Wounds using the Medicine skill, like what happened to Haste in Pathfinder (every new ability that works like haste has to mention it doesn't stack with haste). By leaving it blank (medicine DC is based on the tool used) they are "futureproofing" the rules against that and are free to add new types of medikit-like tools (like a bacta tank or healing bots) without being limited to what is already written on the core rulebook.