Following multiple rib fractures with an ipsilateral pneumothorax, which pulmonary function test is MOST effective to measure improvement in ventilation?

• A. Alveolar ventilation
• B. Inspiratory capacity
• C. Minute ventilation
• D. Total lung capacity

Answer: (B)

When ventilation improves after chest trauma, the key signal is how much air you can draw into the lungs after a normal breath out. That is inspiratory capacity—the amount you can inhale after a typical exhalation, which equals tidal volume plus inspiratory reserve. After multiple rib fractures and a pneumothorax, deep breathing is limited by pain, chest wall stiffness, and air leakage. As healing occurs and those factors lessen, the ability to take a larger, deeper breath increases. Inspiratory capacity directly captures this improvement in the volume you can actively inspire, making it the most sensitive and relevant measure of improved ventilation in this setting.

Alveolar ventilation isn’t a standard pulmonary function test metric, and minute ventilation depends on both breathing rate and depth in a way that can vary with effort and metabolic need. Total lung capacity can improve as the patient recovers, but it’s influenced by multiple factors and is less immediately reflective of functional gains in deep breathing after trauma.