Intermittent mandatory ventilation

IMV Intermittent mandatory ventilation a mode of ventilation designed to deliver a preset inspiratory rate ... 

SIMV Synchronized intermittent mandatory ventilation a ventilator breath "synchronized" with patient s inspiratory effort. 

INTERMITTENT MANDATORY VENTILATION (IMV)/ SYNCHRONIZED INTERMITTENT MANDATORY VENTILATION (SIMV)... 

FIGURE 2 Nitric oxide (NO) synthase inhibition with nitro-L-arginine (L-NA) increases basal total pulmonary resistance per kilogram (TPR/KG) and attenuates the decline in TPR during ventilation with and without hyperoxia in the premature lamb. As shown, the immature lung is responsive to inhaled NO (20 ppm). IMV, intermittent mandatory ventilation BL, baseline. [From Kinsella et al. (35).]... 

FIGURE 4 Inhaled nitric oxide (NO) lowers pulmonary vascular resistance (PVR) and improves gas exchange during prolonged ventilation of premature lambs with severe experimental respiratory distress syndrome. IMV, Intermittent mandatory ventilation Fi02, inspired O2 fraction. [From Kinsella et at. (34).]... 

Synchronized intermittent mandatory ventilation A mandatory mode of ventilation that is combined with a spontaneous mode and allows the patient to initiate and breathe spontaneously while monitoring the total volume of spontaneously delivered breaths and supplementing with mandatory breaths as needed. 

Synchronous intermittent mandatory ventilation (SIMV)—this mode permits the patient to breathe on their own (spontaneous ventilation), but supplements the volume that the patient breathes according to a set breathing rate. For example, the SIMV rate may be set to 4 breaths per minute while the patient is breathing low volumes at a rate of 20 breaths/min. Every 12 s, the ventilator will assist a patient-triggered breath and deliver an adequate tidal volume. If the patient stops breathing, then the ventilator will deliver a set volume of gas 4 times/min. 

Abbreviations VC, volume control VA, volume assist PC, pressure control PA, pressure assist PS, pressure support PR, pressure release Sp, spontaneous unassisted SIMV, synchronized intermittent mandatory ventilation. 

Weaning can be assisted with stable support techniques, which include multiple daily T-piece trials alternating with periods of ventilatory support, and techniques of progressively reducing ventilatory support such as synchronized intermittent mandatory ventilation (SIMV) and PSV. Prospective randomized trials of daily T-piece trials, PSV, or SIMV among intubated patients (39) favor T-piece and PSV approaches over SIMV. There is no evidence that more recent modes of ventilation further improve weaning outcomes (40). 

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