The fiberscope is a medical device used to examine and diagnose lung diseases, and by looking inside the airways, it can help doctors diagnose diseases such as pneumonia, lung cancer, and emphysema. It is inappropriate to use a fiberscope to remove sputum if the patient has no sputum. This is because fibrinoscopy is an invasive test that can cause damage to the airways, and there is no need for this invasive test if the patient has no sputum.