Which of the following statement is true about physiological dead space?
The PCO2 is used for measuring physiological dead space and not the PO2. Second choice is incorrect because the physiological dead space contains the anatomic dead space, and may be substantially larger if there is inequality of ventilation and blood flow within the lung. This is the reason why the physiological dead space is frequently increased in lung disease. Ref: Levitzky M.G. (2007). Chapter 5. Ventilation-Perfusion Relationships. In M.G. Levitzky (Ed), Pulmonary Physiology, 7e.
It is sometimes measured using the aerial PO2
It is generally smaller than the anatomic dead space
It is often increased in lung disease
It is determined primarily by the geometry of the branching airways