## Volume-Controlled Ventilation (VCV) — Guaranteed Tidal Volume **Key Point:** VCV (also called volume-cycled or volume-limited ventilation) delivers a preset tidal volume to the patient with each breath, regardless of changes in lung compliance or airway resistance. ### Mechanism of VCV 1. Clinician sets **tidal volume (Vt)** — e.g., 6 mL/kg ideal body weight in ARDS 2. Ventilator delivers this volume at whatever **pressure is needed** 3. Inspiration ends when the preset volume is delivered (volume-cycled) 4. Peak inspiratory pressure (PIP) varies based on respiratory mechanics ### VCV vs. PCV Comparison | Parameter | VCV | PCV | |-----------|-----|-----| | **Controlled variable** | Tidal volume (fixed) | Inspiratory pressure (fixed) | | **Peak pressure** | Variable (increases with resistance/↓compliance) | Fixed (preset) | | **Tidal volume** | Guaranteed | Variable (depends on compliance) | | **Minute ventilation** | Guaranteed | Variable | | **Risk** | Barotrauma if PIP rises excessively | Hypoventilation if compliance worsens | | **Best use** | Stable lungs, need guaranteed minute ventilation | ARDS, severe lung injury, need low pressures | ### Clinical Advantages of VCV **High-Yield:** VCV ensures **guaranteed minute ventilation** — critical in patients with changing lung mechanics (e.g., during weaning, in sepsis with fluid shifts). **Clinical Pearl:** In VCV, if airway resistance suddenly increases (e.g., secretions, tube kink), peak pressure rises to maintain the preset tidal volume. Monitor PIP closely to prevent barotrauma. **Mnemonic:** **VCV = Volume Guaranteed** — the ventilator will generate whatever pressure is needed to deliver that volume. ### When VCV is Preferred - Neuromuscular paralysis (apneic patients) - Need for guaranteed minute ventilation - Stable lung compliance - Weaning phase (predictable minute ventilation) [cite:Gupta & Sharma Mechanical Ventilation Ch 3]
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