What occurs to perfusion due to collapsed alveoli during a pneumothorax?

During a pneumothorax, the presence of collapsed alveoli leads to a significant mismatch between ventilation and perfusion, often referred to as a V/Q mismatch. This occurs because the collapsed sections of the lung are not participating in gas exchange due to their inability to be ventilated properly. As a result, even if blood flow (perfusion) is still occurring through the pulmonary capillaries, the lack of effective ventilation in the affected alveoli means that oxygen cannot be adequately delivered to the blood.

This mismatch can result in hypoxemia and decreased oxygen levels in the bloodstream because the areas of the lung that are still functioning are unable to compensate for those that are collapsed. In severe cases, this disruption in the balance of ventilation and perfusion can lead to significant physiological distress and require medical intervention to restore normal lung function and oxygenation.