Intermittent Mandatory Ventilation: What's in a Name?

Hence, there is a need for the ventilator, in general, to provide for both spontaneous and mandatory breaths on an intermittent basis. This was the motivation for inventing IMV in the first place, as Kacmarek and Branson mentioned in their paper.1 How does recognition of only type 1 IMV (as in the article by Kacmarek and Branson1) impair our understanding of modes? There are only 3 basic goals of mechanical ventilation (safety, comfort, and liberation),7,8 and the unique benefit of IMV is that can serve all three. All forms of IMV allow presetting of a minimum minute ventilation, serving the goal of safety. Allowing spontaneous breaths to suppress mandatory breaths serves the goal of comfort because spontaneous breaths are invariably more synchronous with patient breathing efforts than mandatory breaths (ie, allowing the patient to control the timing of breaths is better than imposing arbitrary values for frequency and inspiratory time). Finally, elimination of mandatory breaths (through automatic suppression) and automatic reduction in ventilatory support is a safe and effective approach to serving the goal of liberation.9,10 But if we only perceive the existence of type 1 IMV and its service of the goal of safety, then we fail to recognize how IMV can effectively serve the all 3 goals of ventilation. Furthermore, perceiving only type 1 IMV, we fail to observe that type 3 IMV is the new paradigm for advanced modes of ventilation (with adaptive, optimal, or intelligent targeting schemes8) that will likely become more common in the future11: Over the last 30 years or so, we have seen modes of ventilation evolve from simple volume assist/control, serving only the goal of safety,7 to complex modes like IntelliventASV12 that use artificial intelligence tools to serve all 3 goals.7 This makes sense in light of the levels of mandatory breath dependence as mentioned above. And if you accept that those levels may occur in any patient at any time, then it follows that the “ultimate mode” of ventilation (yet to be invented) would be able to provide all levels: full support with all mandatory breaths, partial support with IMV, or some level of assistance with all spontaneous breaths, switching between levels automatically according to patient need. It does not take much imagination to see that this ultimate mode of ventilation would be, by definition, some sort of IMV. What remains to be developed are the ultimate targeting schemes8 for controlling and coordinating the mandatory and spontaneous breaths. Other modes will not be needed except (perhaps) in rare specialty applications. Hence, I assert that in the not too distant future, virtually all modes will be some form of IMV.