Draco sent his patronus after the one coming toward him. He was more worried about the ones going after Remus. Draco shouted Remus's name in an attempt to distract the dementors. Hopefully it would give him strength enough to get away.

The fox then went charging after the ones that sought Remus. He wasn't going to let them get him. His own heart pounded and fear gripped his heart, but his determination to save the older man kept him where he was.