Just to illustrate my theory:
This is Shizune healing Raidou. My guess is that she is transfering some of her chakra to him.http://www.angelfire.com/bug/quexbot/chakra.jpg
For obvious reasons, I couldn't state the fact that supports my theory there.
BTW, I think its strange that Tsunade didn't send a medical ninja with Shikamaru's mission. She was so adamant about it it the past... go figure.