Effective alveolar recruitment will be manifested by which of the following clinical outcomes?

Effective alveolar recruitment aims to improve ventilation and oxygenation in the lungs by opening collapsed or underperfused alveoli. The correct answer indicates a combination of clinical outcomes that demonstrate improved gas exchange and pulmonary function.

A decrease in the A-a (alveolar-arterial) gradient suggests that there is better matching of ventilation and perfusion, resulting in more efficient gas exchange. An increase in the PF (PaO2/FiO2) ratio indicates improved oxygenation, reflecting a positive response to recruitment maneuvers by enhancing the areas of the lung that are participating in gas exchange. Additionally, a decrease in Qs/Qt (shunt fraction) signifies that there is less blood flow going through non-ventilated or poorly ventilated areas, which also aligns with improved recruitment of alveoli and overall better oxygen delivery to the blood.

These outcomes together affirm that alveolar recruitment has taken effect, leading to improved ventilation-perfusion matching, enhanced oxygenation, and reduced shunting. This is why option A is considered the correct choice, as it encapsulates the key physiological responses associated with effective alveolar recruitment.