Recognize Dynamic Hyperinflation (Air-Trapping) at the Bedside Using the Flow Curve

Dynamic hyperinflation (autoPEEP, air trapping, etc.) is a process leading to an increase in end-expiratory lung volumes and increased airway pressures. This process may occur secondary to obstructive lung pathology and/or an increase in minute-ventilation without sufficient time for expiration. The pathologic effects of dynamic hyperinflation include an increased work-of-breathing, barotrauma, pneumothorax, and an increase in intrathoracic pressure leading to a decrease in cardiac output and possible hemodynamic collapse. Rapid identification of this process is crucial for reversing it. One tool for identifying autoPEEP is using the flow curve on the mechanical ventilator at the patient's bedside. At the end of expiration, flow should be zero or near-zero. The presence of airflow at the end of expiration signifies a build up of end-expiratory lung volume and the presence of dynamic hyperinflation. See the graphic and videos below: