- Airway pressure release ventilation (APRV) is a pressure-controlled, time-cycled mode of intermittent mandatory ventilation.
- As well as mandatory breaths, spontaneous breaths can occur at any point throughout the respiratory cycle. These spontaneous breaths are advantageous as they provide more even ventilation throughout the lungs and augment cardiac filling.
- The mandatory breaths involve a long inspiratory time followed by a very short expiratory time. This effectively creates inverse I:E ratio ventilation. Air can be expelled during the expiratory phase when the pressure is ‘released’.
- The breaths are controlled by selecting an inspiratory time and pressure (the Phigh and T high) and an expiratory time (the Plow and T low). The ‘slope’ can also be set. This defines the duration of the pressure increase from lower to higher pressure levels and is measured in seconds
