Which ventilation mechanism mimics natural breathing by transmitting negative pressure from the chest surface to the pleural and alveolar spaces?

• A. Negative Pressure Ventilation
• B. Positive Pressure Ventilation
• C. Baseline Pressure
• D. Fluidic Circuit

Answer: (A)

Mimicking natural breathing involves creating negative pressure around the chest so the pleural and alveolar spaces become more negative than the outside air, pulling air into the lungs. That’s exactly what negative pressure ventilation does: it surrounds the chest with sub-atmospheric pressure, allowing the chest wall to expand, the lungs to fill, and air to flow in as in spontaneous inspiration. In contrast, positive pressure ventilation delivers breaths by increasing pressure inside the airways to push air into the lungs, rather than pulling air in with chest wall negative pressure. The terms baseline pressure and fluidic circuit refer to different concepts or technologies and do not describe the chest-pressure transmission that characterizes negative pressure ventilation.