Explain whether the ventilation–perfusion mismatch in this patient is due to alveolar hypoventilation, intrapulmonary shunting, dead-space ventilation or a combination of these factors

Question

What will be an ideal response?

Answer 1

Suggested response: The patient's CXR was reported to show alveolar infiltrate involving the right middle and lower lobes. A combination of factors relating to the immune response of the lungs result in the presence of infiltrates: alteration in alveolar capillary permeability that leads to an increase in protein-rich fluid in the alveoli; increase in mucus production; and consolidation in the alveoli caused by accumulation of debris from the large number of white blood cells involved in the immune response. This results in intrapulmonary shunting where blood is ‘shunted' through areas of the lung without gas exchange occurring, resulting in hypoxaemia. The elevated respiratory rate associated with the patient's presentation may also impact on ventilation–perfusion mismatch due to alveolar hypoventilation. Rapid, shallow breathing can result in under-ventilation of the alveoli, further compromising gas exchange, resulting in hypercapnoea.