

Hypoxemia results from reduced PaO2 (Powers & Dharmoon, 2023).Ĭonditions that cause changes or collapse of the alveoli (e.g., atelectasis, pneumonia, pulmonary edema, and acute respiratory distress syndrome) impair ventilation. A dead space results in a high ventilation/perfusion (V/Q) ratio, decreasing alveolar ventilation and reducing PaO2 for functional alveoli. Dead space is the volume of a breath that does not participate in gas exchange.

These concentration differences must be maintained by ventilation (airflow) of the alveoli and perfusion ( blood flow) of the pulmonary capillaries.Ī balance between the two exists typically, but certain conditions can alter this balance causing gas exchange impairment. Diffusion of oxygen and carbon dioxide occurs passively, according to their concentration differences across the alveolar-capillary barrier. Gas is exchanged between the alveoli and the pulmonary capillaries via diffusion.
