In Aruba we work a code alone in the back quite often, when back-up is unavailable or more than 20 minutes away.
We focus on good BLS, intubation and defib, leaving the meds for the ER. In 90% of the cases wo don't know it's a code untill we get there, so back-up won't be on the way untill we get on scene. Sometimes I even take un-trained people on-board to do chest-compressions, by showing them first how to do it, and giving them instructions on the way. It's not that we have a choice.