A pulmonary embolism primarily affects lung function by:

A pulmonary embolism primarily affects lung function by creating dead space. In the context of a pulmonary embolism, a blood clot or obstruction in the pulmonary vasculature leads to a region of the lung being ventilated but not adequately perfused. This mismatch results in "dead space," where the areas of the lung receive air but do not participate in gas exchange because the blood flow is obstructed.

When a section of the lung is ventilated without corresponding perfusion, the efficiency of oxygenation and carbon dioxide removal is compromised, which can lead to hypoxemia and other respiratory complications. Dead space can be categorized into anatomical dead space, which is always present in the conducting airways, and physiological dead space, which increases when regions of the lung receive air without blood flow, as seen in pulmonary embolism.

Recognition of dead space as a cornerstone of the pathophysiology of pulmonary embolism is essential for understanding the impact on gas exchange and overall lung function. The other options, while relevant to lung function, do not directly describe the primary mechanical alteration caused by a pulmonary embolism as affecting ventilation and perfusion synchrony in this specific manner.