Vent Modes Explained Like You're Five

Ventilators are scary. They've got more buttons than a cockpit, alarms that never stop, and modes with names like "SIMV + PS" that sound like someone just keyboard-smashed when their phone dropped on it.

Let me help translate ventilator modes into a language that won't make your brain hurt.

Volume Control (VC or AC-VC)

You tell the vent: "Deliver THIS MUCH air, every time, no matter what." The vent delivers that exact tidal volume (like 450 mL) whether the lungs like it or not (bloop).

Good for: Consistent, reliable breaths. Completely controlling ventilation.

Bad for: High pressures if lungs are stiff. Not comfortable for awake patients.

Kid version: It's like a mom who says "You WILL eat these 10 bites" regardless if you like asparagus or not.

Pressure Control (PC or AC-PC)

You tell the vent: "Push air in at THIS PRESSURE, and whatever volume gets in, gets in." The vent hits a pressure target, and stops.

Good for: Lung protection. Lower risk of barotrauma. More comfortable for patients.

Bad for: Volume can vary. If lungs get stiffer, less air gets in.

Kid version: Mom says "Eat until you're full" but controls how much force she uses to convince you.

SIMV (Synchronized Intermittent Mandatory Ventilation)

You set a rate (like 16 breaths/min). The vent delivers those. If the patient wants MORE breaths, they can take them on their own, and that’s okay!

It's a hybrid. Some mandatory breaths, some spontaneous.

Kid version: "I'll make you 3 meals a day, but if you want snacks in between, help yourself to the pantry."

Pressure Support (PS)

Patient does ALL the work of triggering breaths. The vent just gives them a boost when they inhale.

Good for: Weaning, awake, spontaneously breathing patients.

Bad for: Doesn't work if patient stops breathing (hello apnea).

Kid version: You're riding a bike and dad is giving you a little push each take off, but YOU'RE doing the pedaling and steering.

CPAP (on a vent)

Just positive pressure. No breaths delivered. Patient breathes entirely on their own against resistance.

Kid version: You're swimming in a pool with floaties. The floaties hold you up but YOU'RE the one kicking your feet and moving your arms.

The Reality

Most patients are on some combination. SIMV + PS. AC + PEEP. It gets complex. But the basics? They're not that bad once you stop letting the acronyms intimidate you. You're not expected to know everything right now. You'll learn by seeing it, adjusting it, and understanding WHY we choose certain modes for certain patients.

Start with the foundations. The rest will come <3