Does doing cpr require that you do mouth to mouth?

No: Most cardiac arrests occur as a result of a rhythm disturbance that prevents the heart from adequately pumping blood. Chest compressions (in the form of cpr) help circulate blood to the lungs and the rest of the body. Because the lungs hold a natural reserve of oxygen, mouth to mouth breathing is not nearly as important as good chest compressions. In adults, effective CPR = push hard & push fast.

In children, cardiac arrests almost always occur as a result of an airway obstruction (i.e. Choking on a piece of food). The heart stops beating specifically because it is not getting enough oxygen from the lungs (because of the airway obstruction). In this case, clearing the airway and providing mouth to mouth breathing is an essential part of cpr.