**Volume:** Delivers a set tidal volume (VT) over a set inspiration time. The volume is fixed but the pressure will vary. Tidal volume is based on ideal body weight (IBW) which is based on height and gender. Normal VT is 6-8 mL/kg while 4-6 mL/kg is lung protective.

**Pressure:** Delivers a set pressure and maintains it over a set inspiration time. The pressure is fixed but the volume may vary with each breath. More comfortable physiologically vs. volume breaths. Usually set with volume setting first, then set to PIP – PEEP.

**PRVC (pressure regulated volume control):** Delivers a set tidal volume and continually adjusts the amount of pressure need to reach the set tidal volume . Inspiratory flow is variable and changes with patient effort and lung mechanics (airway resistance, lung compliance). Initially delivers a volume test breath upon starting PRVC (and at other times) to determine the pressure needed, then continues to calculate the pressure needed to deliver the set tidal volume. It never adjusts more than 3 cmH2O of pressure with each breath.