A new study has shown an inclination by emergency medical services personnel to hyperventilate (providing too many breaths, and too deep) patients throughout CPR of out-of-hospital cardiac arrest. A follow-up animal study showed ventilation rates just like those in the field which resulted in higher accrued intrathoracic (chest) pressures, decreased coronary perfusion pressures, and reduced survival.
During the recoil phase in CPR, a vacuum is formed inside the chest, drawing blood back to the heart. excessive and deep ventilations mean that less blood returns to the heart between compressions, doubtless reducing the effectiveness of CPR.
At Carpenter CPR, we emphasize the importance of providing breaths at proper intervals, and ONLY providing breath until the chest just begins to rise.