Pressure-controlled ventilation (PCV) has which key advantage over volume-controlled ventilation (VCV) in a patient with acute lung injury?

• A Ensures delivery of a precise tidal volume regardless of lung compliance changes
• B Eliminates auto-PEEP in patients with obstructive airway disease
• C Guarantees higher mean airway pressure to prevent atelectasis
• D Provides a decelerating inspiratory flow waveform, improving gas distribution and reducing peak airway pressures ✓

Explanation

In PCV, inspiratory pressure is preset and flow is variable — beginning high then decelerating as alveolar pressure equilibrates with set pressure. This decelerating flow waveform distributes gas more homogeneously across alveoli with different time constants (compared to the square-wave flow of VCV), reduces peak airway pressure, and may improve oxygenation. The limitation of PCV is that tidal volume varies with changes in lung compliance and resistance — worsening compliance reduces tidal volume, requiring close monitoring. In ALI/ARDS, the lung-protective ventilation strategy (6 mL/kg ideal body weight, Pplateau <30 cmH2O) can be achieved with either mode.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.