Final answer:
Spirometry measures lung volumes to diagnose lung diseases. In restrictive lung diseases like pulmonary fibrosis, FVC is reduced but the FEV1/FVC ratio remains normal or elevated. This contrasts with obstructive diseases, where the FEV1/FVC ratio is typically low due to airway obstruction.
Step-by-step explanation:
Spirometry Findings for Restrictive Lung Disease
Spirometry is an essential diagnostic tool that measures lung volumes to differentiate between types of lung diseases, such as restrictive and obstructive lung diseases. Restrictive lung disease is characterized by a reduced force vital capacity (FVC), indicating a lower amount of air that can be forcibly exhaled after taking the deepest breath possible. It is also marked by a normal or high FEV1/FVC ratio, typically between 88 to 90 percent. This is because, despite the reduction in lung volume, the airways are not obstructed, allowing air to be expelled quickly. Restrictive lung diseases include conditions such as respiratory distress syndrome and pulmonary fibrosis, where lung tissue becomes less compliant and more fibrotic, making it difficult for the lungs to expand properly. As a result, FVC is much lower than normal, and breathing becomes difficult due to the stiffness of lung tissues.
In contrast, obstructive lung diseases such as asthma exhibit a lower FEV1/FVC ratio, typically less than 69 percent, due to airway obstruction that slows down exhalation. Here, the lungs may be more compliant, but the resistance in airways makes it hard to expel air, thus taking a longer time to exhale fully.
Total lung capacity (TLC) is another important measure that can be affected in restrictive diseases. TLC may also be reduced in restrictive lung diseases due to the limited expansion of lung tissues. Altogether, spirometry provides vital information on lung function that can lead to the diagnosis and differentiation of lung diseases.