VCV-A — Assisted Volume Controlled Ventilation
Volume-controlled breaths the patient can trigger. A set tidal volume is delivered on every triggered or timed breath; inspiratory pressure varies with compliance and resistance.
Waveforms
Physiological basis
VCV-A uses the same assist-control logic as PCV-A, but the controlled variable is volume, not pressure: the set tidal volume is delivered precisely with every patient effort. Guaranteed volume is a major advantage where CO₂ control is critical.
Because pressure changes with compliance and the fixed device flow may not match patient demand, patient–device asynchrony (especially flow starvation) is more common than in pressure modes.
Adjustable parameters 9
End-expiratory pressure; for alveolar patency and triggering.
The precise tidal volume delivered with each breath.
Minimum required respiratory rate; the patient may exceed it.
Tidal volume delivery time.
Barotrauma protection against compliance changes.
Lower limit for a low-compliance or leakage warning.
Spontaneous effort detection threshold.
Early re-triggering prevention period.
Atelectasis prevention: a periodic deep breath.