How Often Does Patient-Ventilator Asynchrony Occur and What Are the Consequences?

Abstract

Mechanical ventilation can be life-saving for patients with acute respiratory failure. In between the 2 extremes of complete and no ventilatory support, both patient and machine contribute to ventilatory work. Ideally, ventilator gas delivery would perfectly match patient demand. This patientventilator interaction depends on how the ventilator responds to patient respiratory effort and, in turn, how the patient responds to the breath delivered by the ventilator. It is now evident that the interaction between patient and ventilator is frequently suboptimal and that patient-ventilator asynchrony is common. Its prevalence depends on numerous factors, including timing and duration of observation, technique used for detection, patient population, type of asynchrony, ventilation mode and settings (eg, trigger, flow, and cycle criteria), and confounding factors (eg, state of wakefulness, sedation). Patient-ventilator asynchrony is associated with adverse effects, including higher/wasted work of breathing, patient discomfort, increased need for sedation, confusion during the weaning process, prolonged mechanical ventilation, longer stay, and possibly higher mortality. Whether asynchrony is a marker of poor prognosis or causes these adverse outcomes remains to be determined.

Proportional Assist Ventilation and Neurally Adjusted Ventilatory Assist

“…That's why when Amal Jubran published her data 1,2 showing where end-expiratory P es is going, it's extremely likely that some of that is dynamic hyperinflation. But there was an initial instantaneous momentary drop in P es in the first minute, and that was different between weaning failures and weaning successes.…”

“…1 As discussed in other papers from this conference, patient-ventilator asynchrony is a very common problem. 2,3 Ventilator manufacturers have developed new ventilation modes that target both pressure and volume and have added adjuncts to pressure-targeted ventilation that are designed to improve synchrony: rise time and breath-termination (ie, cycle) criteria. 4 Some ventilator manufacturers have tried to automate these functions to ensure that gas delivery changes as patient demand changes, 4 but despite these new options, asynchrony is still a major problem.…”

Identifying Patient-Ventilator Asynchrony Using Waveform Analysis

“…Mechanical ventilation is used in intensive care units (ICUs) in order to decrease the work of breathing, maintain the adequate gas exchange, and unloading the respiratory muscles [1][2][3]. However, these goals can be difficult to achieve if there is not an adequate interaction between patient and ventilator, which is known as patient-ventilator asynchrony (PVA)3.…”

Early Paralysis for the Management of ARDS

“…27 Epstein 28 reported that only 30% of ARDS subjects suffered from ineffective ventilator triggering compared with subjects with respiratory failure from other mechanisms. 27,28 If the incidence of asynchrony is low, then intervention with NMBAs may not be advantageous. If asynchrony is problematic in a patient with ARDS, then other non-pharmacologic interventions might effectively improve patient-ventilator dynamics.…”