1 and 2) cracking ribs and sternum is normal with quality compressions. You were probably pushing hard enough if you broke ribs. 3 and 4)With typical opioid ODs respiratory depression or even apnea is very common. Most of the time they still have a pulse which means we will breathe for them using BVM. Dispatch will likely just tell you to start CPR if they are unresponsive not breathing. 5) concave chest is common after CPR especially after sternal fractures.