Which parameters cannot be directly obtained from spirometry?

The correct answer is A, as Functional Residual Capacity (FRC) and Total Lung Capacity (TLC) cannot be directly measured using standard spirometry techniques. Spirometry primarily measures the volume of air that can be inhaled and exhaled, focusing on parameters like tidal volume, expiratory reserve volume, inspiratory capacity, and vital capacity.

To understand why FRC and TLC cannot be directly measured, it's important to consider their definitions:

• FRC is the volume of air remaining in the lungs after a normal exhalation.

• TLC is the total volume of air in the lungs after a maximal inhalation.

Measuring these volumes would require techniques that assess the air remaining in the lungs after normal exhalation or after complete inhalation, respectively, which are not functions of standard spirometric tests.

Other options include measurements that can be derived from spirometry. For instance, Inspiratory Capacity can be calculated as the sum of tidal volume and inspiratory reserve volume (both measured during spirometry), and Vital Capacity can be determined by using the forced vital capacity obtained from the test. Thus, while FRC and TLC require additional methods or equipment such as body plethysmography or gas dilution techniques for direct measurement