6.8 Volume Assured Pressure Support/Pressure Augmentation
Volume Assured Pressure Support
Volume Assured Pressure Support (VAPS) is described as a dual control mode within a breath, and may also be called Pressure Augmentation depending on the ventilator. We are discussing this mode under spontaneous modes, as a key component of using it in practice, as the patient has the ability to trigger breaths and has a consistent drive to breathe.
Ventilation starts with a patient-triggered pressure support breath, but volume is targeted, so pressure will be adjusted to achieve the target volume. Breaths are patient-triggered, volume targeted, pressure supported and flow cycled. The difference between this mode and other volume targeted dual modes, is that the ventilator makes adjustments within the same breath, as follows: the clinician typically sets a [latex]V_T[/latex] target, a minimum [latex]RR[/latex], set pressure support, inspiratory flow and sensitivity.
If [latex]V_T[/latex] is met before inspiratory flow drops to the preset level for cycle, then the breath is simply a PSV breath. If monitored [latex]V_T[/latex] is less than the target volume, the ventilator maintains the set flow until the volume is delivered and the ventilator switches from flow cycle to volume cycle.
