Pulmonary Function Testing & Interpretation Flashcards
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On a flow-volume loop, a concave (scooped-out) appearance of the expiratory limb is characteristic of which condition?
Answer: Obstructive lung disease
Obstructive lung disease produces a concave expiratory limb on the flow-volume loop because airflow becomes progressively reduced as lung volumes decrease.
A methacholine challenge (bronchoprovocation) test is primarily used to evaluate for which condition?
Answer: Bronchial hyperresponsiveness consistent with asthma
Methacholine challenge testing measures bronchial hyperresponsiveness; a positive test (PC20 ≤8 mg/mL) supports a diagnosis of asthma.
Maximum Voluntary Ventilation (MVV) measures which respiratory parameter?
Answer: The maximum volume breathed in and out over 12-15 seconds extrapolated to one minute
MVV is measured by having the patient breathe as rapidly and deeply as possible for 12-15 seconds; the result is extrapolated to L/min and reflects respiratory muscle endurance and airway function.
Peak expiratory flow (PEF) monitoring is most commonly used to assess which chronic respiratory condition?
Answer: Asthma
PEF monitoring is integral to asthma action plans, allowing patients to detect airflow changes and adjust therapy based on their personal best values.
Body plethysmography is required to accurately measure which lung volume that cannot be measured by spirometry alone?
Answer: Functional Residual Capacity (FRC)
Body plethysmography uses Boyle's Law to measure FRC (the volume of gas remaining in the lungs at the end of a normal exhalation), which includes residual volume not accessible to spirometry.
The multiple-breath nitrogen washout test is used to measure which lung parameter?
Answer: Functional Residual Capacity (FRC)
The nitrogen washout technique measures FRC by having the patient breathe 100% oxygen until exhaled nitrogen concentration approaches zero, allowing calculation of the starting gas volume.
When interpreting spirometry, percent predicted values are derived by comparing patient results to which reference standard?
Answer: Age-, height-, sex-, and ethnicity-matched reference population data
Predicted values are calculated from regression equations derived from healthy nonsmoking reference populations, accounting for age, height, sex, and ethnicity.