Identifying asynchronies: Reverse trigger

Abstract

A variety of asynchronies between the patient’s respiratory efforts and the programed ventilatory settings have been categorized. Reverse trigger is described as an inspiratory effort occurring after a ventilator-initiated breath and may represent a form of respiratory entrainment. In other words, the ventilator triggers muscular efforts. It often appears in a repetitive, stereotyped pattern. It occurs often in mechanically ventilated patients at risk of injury, might be underrecognized at the bedside and may has adverse effects on oxygenation and ventilation, as well as potentially increasing lung injury. We can phenotype these events using the Campbell diagram (pressure–volume loop) by differentiating their occurrence during inspiration and expiration. Reverse trigger with sufficient inspiratory effort and duration can result in an additional ventilator-delivered stacked breath, which can cause large tidal volumes and increased transpulmonary pressure. Keywords: Asynchrony, ventilator, reverse trigger, entrainment, lung injury, phenotype.