Respiratory Rate as a Factor in Lung Injury—Not Just What You Set, but How You Set

Respiratory support with mechanical ventilation is crucial for critically ill patients with diseases such as acute respiratory distress syndrome (ARDS), in which the pulmonary gas exchange capacity is impaired. However, ventilation itself exposes the lungs to a nonphysiologic environment, which in itself injures the lungs. Reports on ventilator settings that have been shown to affect patient outcomes have focused on low tidal volume (V_T)¹  and adequate driving pressure.²  Additionally, the concepts of pressure (barotrauma), V_T (volutrauma), and cyclic opening–closing of the lung units (atelectrauma) have been proposed as mechanisms of ventilation-induced lung injury. Ventilator settings that minimize each of these factors were subsequently studied and discussed. Although the respiratory rate is an essential item in the ventilator setting, it has received little attention because it is passively adjusted after the V_T setting. Animal studies have shown that increasing the respiratory rate exacerbates ventilation-induced lung...