Identifying asynchronies: Delayed triggering

Patient-ventilator asynchronies can occur at any phase throughout the respiratory cycle. Because it has been associated with patient outcomes, it is important to recognize and address these asynchronies. Bedside interpretation of air flow and airway pressure waveforms are helpful for recognizing patient–ventilator asynchronies and optimizing ventilator settings. Patient effort is sensed by either a drop in circuit pressure (pressure trigger) or circuit bias flow (flow trigger). Triggering delay is the time interval between the start of the neural and mechanical inspiration. Triggers must be sensitive enough to recognize patient effort to avoid imposing an additional load but not too sensitive to avoid auto-triggering. Despite improvements in triggering technology, triggering asynchronies continue to occur and are manifest, among others, by delayed triggering. Keywords: asynchrony, patient effort, trigger, delayed triggering