Airway pressure release ventilation (APRV). A human trial

Area of Science:

• Critical Care Medicine
• Respiratory Physiology
• Anesthesiology

Background:

• Post-operative management following coronary revascularization often requires mechanical ventilation.
• Conventional positive pressure ventilation (PPV) can lead to high peak airway pressures, potentially exacerbating lung injury.
• Alternative ventilation strategies are needed to optimize gas exchange while minimizing ventilator-induced lung injury.

Purpose of the Study:

• To compare the efficacy of Airway Pressure Release Ventilation (APRV) with conventional Positive Pressure Ventilation (PPV) in patients recovering from coronary revascularization.
• To evaluate gas exchange and hemodynamic stability during APRV and PPV.
• To assess the feasibility of weaning from APRV in this patient population.

Main Methods:

• 14 adult patients undergoing operative coronary revascularization were studied.
• Data were collected during conventional PPV and subsequently during APRV.
• APRV settings were adjusted to maintain normal PaCO2, with a gradual decrease in spontaneous breathing frequency until patients were on Continuous Positive Airway Pressure (CPAP).

Main Results:

• Gas exchange (pHa, PaO2/FIO2) and hemodynamic variables were comparable between PPV and APRV.
• All patients were successfully weaned from APRV without complications.
• APRV resulted in significantly lower peak airway pressures compared to PPV.

Conclusions:

• APRV effectively supports oxygenation and ventilation in patients with mild acute lung injury, such as those recovering from coronary revascularization.
• APRV demonstrates a potential advantage over PPV by utilizing lower peak airway pressures.
• Optimal ventilator design should prioritize CPAP as a primary intervention, with secondary augmentation of alveolar ventilation, aligning with APRV's capabilities.