Flow-volume loops that are narrowed due to diminished lung volumes are characteristic of which condition?

The narrowing of flow-volume loops as a result of diminished lung volumes is indeed characteristic of kyphoscoliosis. In this condition, the structural abnormalities of the spine lead to a restrictive pattern of lung function. This structural distortion reduces the capacity of the lungs to expand fully, resulting in lower lung volumes.

The flow-volume loop reflects these changes by showing a smaller overall volume capacity, which appears as a narrowing in the loop. In kyphoscoliosis, the restrictive nature of the pulmonary mechanics is due to the thoracic deformities that can impact diaphragm movement and overall lung expansion. As a result, patients experience limitations in airflow during both inhalation and exhalation phases.

In contrast, conditions like asthma and COPD are characterized by obstructive patterns in the flow-volume loop, where there is usually a more significant discrepancy between the forced expiratory flow and the volume curve, rather than a narrowing due to reduced lung volumes. Pneumonia can also cause lung volume changes but typically does not result in the same kind of consistent narrowing seen in kyphoscoliosis.