VCV — Volume Controlled Ventilation
A set tidal volume is delivered precisely every cycle; ventilation is device-controlled and inspiratory pressure varies with compliance and resistance.
Waveforms
Physiological basis
VCV dynamically adjusts the pressure needed to deliver the set tidal volume. Classic VCV uses a constant (square) flow: a steady flow runs through inspiration, which ends when the volume target is met. This gives predictable minute ventilation and CO₂ control, but peak pressure is uncontrolled, so compliance changes can raise barotrauma risk.
VCV is the most widely used mode worldwide — global studies show it is chosen for roughly 60% of total ventilation time — mainly because of its predictable control of minute ventilation and CO₂ removal.
Adjustable parameters 7
Affects oxygenation; prevents alveolar collapse.
Precise tidal volume delivered with each breath. Target 6–8 ml/kg IBW.
Directly determines CO₂ removal and minute ventilation.
Constant-volume delivery time; affects the I:E ratio.
Safety limit against barotrauma; an alarm is raised if exceeded.
Lower limit for detecting circuit leakage or abnormally low compliance.
1.5× volume every 20 breaths; atelectasis prevention.