Identifying asynchronies: work shifting and double triggering

Mechanical ventilation supports the work of breathing, improves gas exchange, and unloads the respiratory muscles, all of which require good synchronization between the patient and the ventilator. Asynchronies occur when the ventilator’s breath delivery does not match the patient’s neural ventilatory pattern or is inadequate to meet the patient’s flow demand. Patient–ventilator asynchrony can be easily detected by observing the patients in those extreme situations in which they fight the ventilator; nevertheless, the vast majority of asynchronies occur without major clinical signs and go undetected or corrected without measuring patient's respiratory effort (either esophageal pressure or electrical activity of the diaphragm). Synchrony problems are common, occurring in perhaps as many as 25% of patients receiving invasive ventilation and up to 80% of patients receiving noninvasive ventilation. In this concise review, we describe work shifting and double triggering asynchronies. Keywords: Patient-ventilator asynchronies, work shifting, double triggering