A chest X-ray revealing a flattened diaphragm and decreased expiratory flow rate suggests what type of pulmonary disease?

A chest X-ray showing a flattened diaphragm and decreased expiratory flow rate indicates the presence of obstructive pulmonary disease. In obstructive pulmonary diseases, such as chronic obstructive pulmonary disease (COPD) or asthma, the airflow is impeded during expiration due to narrowed or obstructed airways. This leads to air trapping and hyperinflation of the lungs.

The flattened diaphragm is a common radiological finding in these conditions, as hyperinflation causes the diaphragm to become more horizontal rather than in its normal dome shape. The decreased expiratory flow rate is a direct consequence of the obstruction in the airways, making it harder for air to be exhaled effectively.

In contrast, restrictive pulmonary diseases often present with a reduction in lung volumes but not typically with a flattened diaphragm. They are characterized by a decreased total lung capacity and may show compliance issues on imaging. Interstitial lung disease is also not indicated by a flattened diaphragm; it typically affects the lung parenchyma and may show different patterns on imaging. Pneumonia would manifest with other characteristic signs, such as consolidation or infection-related changes in the lung fields, rather than a flattened diaphragm.

Thus, the combination of a flattened diaphragm and decreased expiratory flow rate is strongly indicative of obstruct