Basics of Ventilator Settings

Abstract

Modern microprocessor-controlled mechanical ventilators are equipped with multiple modes and have the ability to monitor flow, pressure, volume and various other lung parameters. Through this chapter we aim to provide the clinician a basic working knowledge of the commonly used modes of mechanical ventilation. The commonly used modes of ventilation are the controlled modes, assist control ventilation (ACV), synchronized intermittent ventilation (SIMV) and pressure support ventilation. The primary advantage of volume-controlled ventilation is that it guarantees tidal volume and minute ventilation, even if lung mechanics keep changing, while pressure-controlled ventilation offers the advantage of lung protection by reducing the risk of overdistension, by limiting inspiratory pressure to set values. ACV and SIMV are partial support modes and offer the advantage of patient participation in breath delivery, thus avoiding muscle atrophy. PSV is a fully spontaneous mode and mostly used for liberation from mechanical ventilation. Thus, mechanical ventilators offer a variety of modes, functions and alarms. A basic understanding of these is mandatory for clinicians to decide the mode and its various settings, once the need for mechanical ventilation has been established.