Final answer:
The FEV1/FVC ratio is used to diagnose lung diseases, with a low ratio indicating obstructive lung disease and a high ratio indicating restrictive lung disease. Spirometry is the technique used to measure these ratios and diagnose the conditions.
Step-by-step explanation:
The student's question revolves around spirometry findings for obstructive lung disease and what changes in the FEV1/FVC ratio may indicate about lung health. Spirometry is a key measurement technique in diagnosing respiratory conditions.
A decrease in the FEV1/FVC ratio (forced expiratory volume in one second to forced vital capacity) indicates obstructive lung disease, such as asthma, where airway obstruction causes slow exhalation and reduced FVC. When the ratio is low (< 69 percent), it denotes that the person has difficulty exhaling air due to this obstruction.
Conversely, an increase in the FEV1/FVC ratio indicates restrictive lung disease, such as pulmonary fibrosis or respiratory distress syndrome, where the lungs become less pliable or stiff.
This results in a high ratio (88 to 90 percent), reflecting that the patient can exhale air quickly, but the total volume is less due to decreased lung compliance. These conditions can be diagnosed with spirometry, which measures both FEV1 and FVC.