A 28-year-old male with ARDS is on mechanical ventilation. The respiratory therapist adjusts the ventilator settings. Which feature best distinguishes Pressure Control Ventilation (PCV) from Volume Control Ventilation (VCV)?

Explanation

## Distinguishing Feature: Pressure vs. Volume Control ### Pressure Control Ventilation (PCV) **Key Point:** In PCV, the ventilator delivers a **preset inspiratory pressure** for a fixed time period. The **tidal volume varies** depending on lung compliance and airway resistance. ### Volume Control Ventilation (VCV) **Key Point:** In VCV, the ventilator delivers a **preset tidal volume** regardless of changes in lung compliance or resistance. The **peak inspiratory pressure varies** to achieve that volume. ### Critical Discriminator | Feature | PCV | VCV | |---------|-----|-----| | **Set parameter** | Inspiratory pressure (fixed) | Tidal volume (fixed) | | **Variable parameter** | Tidal volume | Peak inspiratory pressure | | **Effect of compliance ↓** | Tidal volume decreases | Peak pressure increases | | **Effect of resistance ↑** | Tidal volume decreases | Peak pressure increases | **High-Yield:** The **best discriminator** is that PCV has a **fixed pressure with variable volume**, while VCV has a **fixed volume with variable pressure**. ### Clinical Pearl - PCV is preferred in patients with **poor lung compliance** (ARDS, pulmonary fibrosis) because it limits peak pressures and reduces barotrauma risk. - VCV is preferred when **minute ventilation must be guaranteed** (e.g., neuromuscular disease, apnea). ### Why This Matters **Tip:** Remember the acronym: **PCV = Pressure set, Volume varies** | **VCV = Volume set, Pressure varies**.