Which feature describes how two-level CPAP (IPAP/EPAP) supports ventilation?

• A. Bilevel Ventilation
• B. Pressure Support Ventilation
• C. Assist-Control
• D. SIMV

Answer: (A)

Two-level CPAP uses two distinct pressures: a higher inspiratory pressure (IPAP) to augment ventilation during inspiration, and a lower expiratory pressure (EPAP) to keep the airways open during expiration. This setup is exactly what bilevel ventilation describes, often called BiPAP. It directly provides inspiratory support at IPAP while maintaining a baseline pressure with EPAP, helping reduce the work of breathing and improve tidal volume.

Pressure Support Ventilation, while it assists inspiration, typically involves a single pressure boost above baseline and doesn’t inherently use two separate pressures for inspiration and expiration. Assist-Control delivers breaths at a set rate with full support on every breath, not defined by two pressure levels. SIMV alternates between mandatory breaths and spontaneous breaths without inherently specifying two pressure levels.