Which therapy should be expected to best respond for a patient with an intrapulmonary shunt and low PaO2 levels?

For a patient with an intrapulmonary shunt and low PaO2 levels, positive pressure ventilation is the most effective therapy because it can help to recruit collapsed alveoli and improve ventilation-perfusion matching. In cases of intrapulmonary shunting, blood flows through the lungs without being adequately oxygenated, which results in hypoxemia that typically does not respond well to supplemental oxygen alone.

Positive pressure ventilation assists in overcoming the low pressures that may be present in the lungs due to mechanical ventilation. It increases lung volumes and can help to open areas of the lung that are not participating in gas exchange, thereby improving oxygenation. This method promotes better distribution of air, decreases work of breathing, and can enhance the removal of carbon dioxide.

While high concentrations of oxygen, such as administering 100% FiO2, may temporarily improve oxygen levels in some patients, it is insufficient for those with intrapulmonary shunting since the underlying issue is not the availability of oxygen but rather the inability of blood to adequately participate in gas exchange. Likewise, simply using oxygen via a nasal cannula or focusing on airway clearance may not rectify the significant shunting impact on oxygenation. Thus, positive pressure ventilation directly addresses the needs related to mechanical ventilation in