Asynchrony and Cyclic Variability in Pressure Support Ventilation

Abstract

Adaptation between the patient and the ventilator has always been the first goal of the physician facing with a patient treated by mechanical ventilation. Sedation is commonly used under invasive ventilation to facilitate it, especially in difficult-to-ventilate patients with acute respiratory Asynchrony and Cyclic Variability in Pressure Support VentilationA. Cuvelier and J.-F. Muirdistress syndrome (ARDS). Adaptation to noninvasive ventilation (NIV) is often difficult to obtain in the acute phase as this mode of ventilation is a “leaky” ventilation, and spontaneous ventilation has to be respected, with contraindication of significant sedation. Thus, specific attention has been brought to this phenomenon called synchrony, which may be defined as the agreement between the patient respiratory efforts and the inspiratory and expiratory time of the ventilator. So, asynchrony may be explained by the inspiratory drive and the airways pressurization, which is secondary to the mechanical and technical characteristics of the machine and the interface, the ventilatory settings, and the pathophysiological abnormalities linked to the etiology of the respiratory failure [1]. This dyssynchrony is the mismatch between patient and ventilator inspiratory time and secondary wasted or ineffective efforts.