Final answer:
The description not characteristic of emphysema is 'rapid onset,' as emphysema progresses gradually due to factors such as smoking, leading to chronic respiratory symptoms and barrel chest, not weight gain.
Step-by-step explanation:
The description that is NOT characteristic of emphysema is rapid onset. Emphysema is a chronic lung disease that progresses gradually, typically due to cigarette smoking, leading to symptoms such as shortness of breath, chronic cough, and wheezing. Damage to the alveoli, decreased lung elasticity, and air trapping are hallmarks of this condition. Furthermore, over time patients may develop complications such as cor pulmonale (heart issues caused by lung disease) and a distinctly shaped barrel chest due to the chronic over-inflation of lungs. However, one would not associate weight gain with emphysema, as the exercise intolerance that comes with this disease tends to lead to weight loss rather than gain.