Which statement regarding positive-pressure ventilation is correct?

• A. With positive-pressure ventilation, more volume is required to have the same effects as normal breathing.
• B. Unlike negative-pressure ventilation, positive-pressure ventilation does not affect the esophageal opening pressure.
• C. To prevent hypotension, the EMT should increase the rate and force of positive-pressure ventilation.
• D. Positive-pressure ventilation allows blood to naturally be pulled back to the heart from the body.

Answer: (A)

Positive-pressure ventilation changes the way air gets into the lungs by pushing it in under pressure during inspiration, which raises intrathoracic pressure. That higher pressure in the chest makes it harder for blood to return to the heart, reducing preload and potentially lowering cardiac output. Because of this, the same breath delivered under positive pressure often doesn’t produce the same level of ventilation and oxygenation as spontaneous, negative-pressure breathing. To achieve the same effect, you typically need a larger tidal volume (more air per breath) when using positive-pressure ventilation. That’s why this statement is the best choice.

The other options conflict with how positive-pressure ventilation interacts with both the cardiovascular system and chest pressures. Increasing rate and force to prevent hypotension can actually worsen hypotension by further decreasing venous return. Positive pressure does affect venous return rather than simply “pulling” blood back to the heart, and it does influence intrathoracic pressures that affect structures in the chest, including how air moves and how blood returns to the heart.