Synchronized Intermittent Mandatory Ventilation

In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan.


Synchronized intermittent mandatory ventilation (SIMV) is a type of volume control mode of ventilation. With this mode, the ventilator will deliver a mandatory (set) number of breaths with a set volume while at the same time allowing spontaneous breaths. Spontaneous breaths are delivered when the airway pressure drops below the end-expiratory pressure (trigger). The ventilator attempts to synchronize the delivery of mandatory breaths with the spontaneous efforts of the patient. In contrast, to assist control ventilation (ACV), SIMV will deliver spontaneous volumes that are 100% driven by patient effort. Pressure support (PS) may be added to enhance the volumes of spontaneous breaths. SIMV was initially developed in the 1970s as a method to wean patients who are dependent on mechanical ventilation. SIMV gained popularity and was the most widely used ventilatory mode for weaning, with 90.2% of hospitals preferring SIMV in a survey conducted in the 1980s.

Publication types

  • Study Guide