I think it's sort of like an Ino thing with Perona. She can send her spirit out at will, and become more in touch with the ghosts she controls. The only downside is that her body's left out in the open, and any damage caused to it will obviously affect her when she returns her spirit back to her body. What will happen in the next chapter is that they'll show a bit of Usopp's fight against Perona, the outcome being pretty short since both of them are fairly weak fighters.

I think instead of going to Chopper and Robin's fight, they'll either go back to Sanji's situation with Absalom, to see if Nami wakes up or not, or it'll go to Zoro and Ryuma's fight.