Consequences of Patient-Ventilator Discordance

The impact of patient-ventilator asynchrony is still unclear. Initial studies in patients with asynchrony showed that it is associated with negative physiologic and clinical outcomes. However, these studies were narrowly focused in many different ways, including the duration of observation and the types of asynchronies included in the study. Research has since not only identified a newly described asynchrony, reverse triggering, but also identified potentially important modifiers of clinical outcomes such as asynchronies occurring in clusters. Our understanding of the magnitude of the patient's inspiratory effort in relation to the degree of support the ventilator is providing to the patient has expanded the potential role asynchrony plays in negative outcomes. More recent studies have identified the implications of overassistance and underassistance on the structure and function of the diaphragm, which is a potential mediator in clinical outcomes. In some cases, the presence of asynchrony is associated with positive clinical outcomes. This review focuses on the clinical outcomes of patient-ventilator asynchrony as well as overassistance and underassistance.