Airway pressure release ventilation

Airway pressure release ventilation (APRV) is a pressure control mode of mechanical ventilation using  an inverse ratio ventilation strategy.

APRV is an applied continuous positive airway pressure (CPAP) that at a set timed interval releases the applied pressure. 

It may be referred to as BiVent.

APRV is a time-cycled alternant between two levels of positive airway pressure, with the main time on the high level and a brief expiratory release to facilitate ventilation.

APRV is indicated in patients with acute lung injury, acute respiratory distress syndrome and atelectasis after major surgery.

Advantages to APRV ventilation include: decreased airway pressures, decreased minute ventilation, decreased dead-space ventilation, promotion of spontaneous breathing, almost 24-hour-a-day alveolar recruitment, decreased use of sedation, near elimination of neuromuscular blockade, optimized arterial blood gas results, mechanical restoration of FRC (functional residual capacity), a positive effect on cardiac output, due to the negative inflection from the elevated baseline with each spontaneous breath, increased organ and tissue perfusion and potential for increased urine output secondary to increased kidney perfusion.

APRV is a type of inverse ratio ventilation: exhalation time is shortened to usually less than one second to maintain alveoli inflation. 

It is basically a continuous pressure with a brief release. 

APRV is the most efficient, conventional mode for lung protective ventilation.

A very similar mode is biphasic positive airway pressure (BIPAP).

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