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# Airway Pressure Release Ventilation (APRV) Airway pressure release ventilation (APRV) is a form of continuous positive airway pressure (CPAP) with two distinct pressure levels. APRV maintains spontaneous breathing throughout the ventilatory cycle at both pressure levels (Figure 3-16). It is a t...

# Airway Pressure Release Ventilation (APRV) Airway pressure release ventilation (APRV) is a form of continuous positive airway pressure (CPAP) with two distinct pressure levels. APRV maintains spontaneous breathing throughout the ventilatory cycle at both pressure levels (Figure 3-16). It is a time-triggered, pressure-limited, and time-cycled mode. **Key Features:** * **Time-triggered:** The clinician sets the high and low pressures, and the inspiratory times for each pressure level. * **Pressure-limited:** The higher pressure helps keep the alveoli inflated and enhances recruitment. * **Time-cycled:** The time interval at the higher pressure (Thigh) is longer than the time spent at the lower pressure (Tlow). * **Pressure release:** Release of pressure from the higher to lower pressure setting helps remove CO2. Time triggering is established using set time intervals for Thigh and Tlow. * **Patient triggering:** Most ventilators allow patient triggering of a breath (either pressure or flow). **Figure 3-16 Details (scalar presentation of APRV mode):** The figure displayed a scalar presentation of the APRV mode. * **Phigh**: Upper airway pressure (15 cm H2O) * **Plow**: Lower airway pressure (PEEP of 5 cm H2O) * **R**: Pressure release (10 cm H2O) * **5**: Beginning of spontaneous breaths at Phigh **Clinical Significance**: * **Inflated alveoli**: Initial setting of higher pressure maintains inflated alveoli and enhances recruitment. * **CO2 removal**: Release of the pressure between a higher to lower pressure setting helps in removal of CO2, as the lower pressure interval is established using the time triggering method. * **Mean airway pressure**: The higher pressure is typically set above the lower inflection point of the lung's pressure-volume curve, close to the mean airway pressure during pressure-controlled ventilation. * **Spontaneous breaths**: The patient may or may not receive pressure support while in spontaneous breath portion depending on the ventilator settings. **ADDITIONAL FEATURES**: Some manufacturers offer pressure support during the spontaneous portion at the higher CPAP level.