This slide discusses the concept of positive pressure ventilation and its contrast to normal respirations.
Normal Ventilation
With Normal Respirations, the pressure in the chest becomes negative when the diaphragm contracts and pulls down.
The negative pressure in the chest now does 2 things:
1. Draws air into the lungs.
2. Draws venous blood into the inferior and superior vena cava increasing the priming pressure for the heart.
The priming effect is lost with artificial Positive Ventilation. This loss of venous priming changes we deliver CPR.