Pneumatic pulse oscillation expectoration instrument is a medical instrument, which is used to help patients with respiratory diseases to expectorate. It stimulates the patient's respiratory tract by generating air pulse oscillation, which makes the sputum loose and excreted, thus improving the patency of the respiratory tract. This kind of equipment usually consists of a main machine and corresponding accessories, such as endotracheal tube, mask, etc. It is a medical tool, not a book.