Which method can help reinflate the lungs after a pneumothorax?

• A. Increase PA (force air in)
• B. Decrease atmospheric pressure
• C. Decrease lung volume
• D. Increase external pressure

Answer: (A)

Reinflating the lungs after a pneumothorax involves the need to overcome the pressure in the pleural space that has developed due to the presence of air outside the lung tissue. Increasing the pressure within the lungs (PA) is an effective method to overcome the negative pressure created by the pneumothorax.

When air is forced into the lungs, it creates an increased pressure internally which can help push the lung tissue back against the thoracic wall, allowing the lung to re-expand and reinflate. This method directly addresses the physics of how pressures interact during ventilation, using the principles of gas exchange and lung mechanics.

In contrast, decreasing atmospheric pressure or lung volume would not provide the necessary forces needed for lung inflation, and while increasing external pressure might seem plausible, it typically would not create the needed conditions for lung reinflation effectively in the case of pneumothorax. Thus, increasing the internal pressure by forcing air in is the most relevant and effective method among the choices.