IPPB stands for intermittent positive pressure breathing and the ratio or relationship between inspiratory time and expiratory time is I:E. The normal inspiratory-to-expiratory ratio value is 1:2, it means if inspiration will occur in 1 second then expiration will take 2 seconds but it can be greater than this. If IPPB is administrated with an inspiratory-to-expiratory ratio of 1:2 or greater sufficient time will be available that allow the heart and vessels to fill with the blood.