Improvement in cardiac output during airway pressure release ventilation

Positive-pressure ventilation is known to affect cardiac output and hemodynamic stability (1). Minimizing the number of positive-pressure breaths and allowing more spontaneous ventilation increase cardiac output by augmenting venous return (2, 3). Airway pressure release ventilation (APRV) is different from other positive-pressure modes of mechanical ventilation. It allows spontaneous ventilation and, by alternating between high and low continuous positive airway pressure levels, causes changes in the functional residual capacity, which augments CO2 elimination (4). This method of ventilation results in lower peak airway pressures and has a minimal effect on cardiac output in animal studies (5). We present a case in which a change in the mode of mechanical ventilation from intermittent mandatory ventilation (IMV) with continuous positive airway pressure to APRV resulted in improvement in the cardiac output of a patient requiring mechanical ventilatory support.