Volume Support or Assist-control Ventilation (VSV or ACV)
- Volume Controlled (but could be pressure controlled)
- Flow-Triggered (but could be anything-triggered)
..typically, there is a backup mode, which is time triggered. In case the patient forgets to breathe.
- Volume- limited, Flow-limited (but doesn't have to be flow-limited)
- Time-Cycled ((but it can be volume-cycled if you don’t want inspiratory pauses)
The volume-controlled ACV gives you limited control over your minute volume. The patient may take as many breaths as he damn well please. With volume-controlled ACV you can control the tidal volume, at least. There is also Pressure-controlled ACV, which is discussed later, and for some reason called PCV (Pressure Controlled Ventilation).
This is slightly better for the partially sedated patient; however, it is still uncomfortable to have the same volume of air rigidly pushed into you.
The workload of breathing is not reduced greatly especially if the flow limit is low. The respiratory muscles continue to contract throughout much of the breath. This was confirmed by an 1986 study which discovered that in some cases patient work-per-litre-of-tidal-volume (WP) was greater with mechanical ventilation than with spontaneous breathing!
In short, its possible that what you are doing is not helpful.