Basic and Clinical Sciences (BCSE) Practice Exam

What is the primary function of a volume displacement spirometer?

1. Measures lung compliance

2. Assesses blood oxygen levels

3. Measures FVC and FEV1

4. Evaluates airway resistance

The correct answer is: Measures FVC and FEV1

The primary function of a volume displacement spirometer is to measure important lung volumes and capacities, specifically the Forced Vital Capacity (FVC) and Forced Expiratory Volume in one second (FEV1). These measurements are vital for assessing lung function and identifying various respiratory conditions. When a person inhales and exhales into this device, it accurately records the amount of air they are able to expel forcefully after taking a deep breath (FVC) and the amount of air expelled in the first second of that effort (FEV1). The ratio of FEV1 to FVC is particularly valuable in differentiating between obstructive and restrictive airway diseases. Other functions, such as measuring lung compliance, assessing blood oxygen levels, or evaluating airway resistance, are not the primary functions of a volume displacement spirometer. Lung compliance assessment typically involves different methodologies that measure how easily the lungs expand. Blood oxygen levels are evaluated using pulse oximeters or arterial blood gas tests, and airway resistance assessment often requires specialized techniques like plethysmography.