What is the most common reason for the chest not rising with each breath during CPR?

The most common reason for the chest not rising with each breath during CPR is that the airway is not clear. When performing CPR, particularly when providing rescue breaths, it is crucial that the airway is unobstructed so that air can enter the lungs effectively. If the airway is blocked—due to tongue obstruction, foreign bodies, or other issues—air cannot flow into the thoracic cavity, leading to ineffective ventilation and the chest not rising.

Ensuring that the airway is patent involves proper positioning, such as tilting the head and lifting the chin to help open the airway. This is a key step in the CPR process, as effective ventilation requires an unobstructed pathway to deliver air to the lungs. Without a clear airway, the positive pressure generated during rescue breathing will not result in proper chest rise and adequate ventilation, which are critical for oxygenation during cardiac arrest situations.