Push hard at a rate of 100 to 120 compressions a minute. If you haven't been trained in CPR, continue chest compressions until there are signs of movement or until emergency medical personnel take over. If you have been trained in CPR, go on to opening the airway and rescue breathing.

If there is a pulse but no breathing, begin rescue breathing- 1 breath every 5 seconds for adults or every 3 seconds for an infant or child ● Recheck pulse after every minute of rescue breathing ● If you are sure there is no pulse, begin CPR if you are trained. If there is a pulse, DO NOT use CPR.

Final answer: Between giving the first and second breath while performing CPR, it's important to allow the chest to fall and the air to exit. This ensures proper deflation of the lungs and circulation of air, displacing carbon dioxide with oxygen.