Principles & Practice of Mechanical Ventilation, 2e >Neil MacIntyre,  Richard D. Branson

Conventional Positive-Pressure Breath-Delivery Strategies/Modes

"Positive-pressure breaths delivered by mechanical ventilators can be classified by the behavior of three variables: (1) the trigger variable (what initiates the breath), (2) the target or limit variable (what controls gas delivery during the breath), and (3) the cycle variable (what terminates the breath).^1–3 Trigger variables are either patient effort (detected by the ventilator as a pressure or flow change) or a set machine timer. Target or limit variables generally are either a set flow or a set inspiratory pressure. Cycle variables generally are a set volume, a set inspiratory time, or a set flow rate. Pressure is often a backup safety-cycle variable. Figure 16-1 uses this classification scheme to describe the five most common breath types available on the current generation of mechanical ventilators...."