What is indicated by decreased values of FEF 200 - 1200?

Decreased values of FEF 200 - 1200 indicate issues primarily associated with large airway obstruction. The Forced Expiratory Flow (FEF) between 200 and 1200 milliseconds specifically measures the flow of air during the early part of the forced expiratory maneuver, relating to larger airways. When these values are diminished, it suggests that there is an obstruction in the flow of air through these larger airways, which can occur in conditions such as asthma or chronic bronchitis, where airflow is hindered.

This is significant because normal airway function would show no decrease in the airflow rates, while restrictive diseases are characterized more by a reduction in lung volumes rather than just decreased flow rates in larger airways. Similarly, decreased lung compliance is related to stiff lungs rather than flow rates, which would be seen more in restrictive lung diseases, not specifically indicated by FEF 200 - 1200 numbers. Thus, the identification of large airway obstruction as indicated by decreased FEF values is crucial for understanding respiratory conditions and their implications.