Asynchrony: Clinical Relevance, Detection, and Resolution

Patient-ventilator asynchrony is defined as a mismatch between the patient's intrinsic timing of inspiratory and expiratory efforts and the ventilator's insufflation and exhalation, reflecting a discrepancy between the patient's needs and the support delivered by the ventilator. Although asynchrony is frequently observed in mechanically ventilated patients, it remains unclear whether patient-ventilator asynchrony directly contributes to adverse outcomes, under what conditions some degree of asynchrony may be tolerated or beneficial, and how this knowledge should guide clinical management. The relationship between asynchronies and clinical outcomes is complex, influenced by multiple factors that may act as mechanisms of harm or benefit. These include the timing of asynchrony (<i>ie,</i> during inspiration or expiration), the magnitude of patient effort, ventilator mode or settings, and patient-specific factors such as lung compliance. Importantly, patient-ventilator asynchrony can also serve as a marker of a patient's underlying clinical condition, offering insight into the patient's respiratory drive. Some forms of asynchrony are associated with high respiratory drive, whereas others occur in the context of low drive or overassistance. This review outlines the underlying mechanisms and clinical implications of patient-ventilator asynchronies. It also offers practical strategies for bedside detection and management and highlights future directions to improve recognition and resolution of patient-ventilator asynchrony in clinical practice.