胸外气道包括鼻、咽、口、喉及气管上段部份。由于这些部位构造解剖形状极不规則,在各种内外环境因素影响下,例如气压、温度、药物、急慢性炎症、过敏、淋巴组织增生、情绪变化等,都使这些部份容积经常变化,空气流通量因受到不同之气流阻力而时刻不同,故目前尚无 Thoracic airways include the nose, pharynx, mouth, throat and upper trachea. Due to the extremely irregular anatomical shape of these parts, the volume of these parts often changes under the influence of various internal and external environmental factors such as air pressure, temperature, drugs, acute and chronic inflammation, allergies, lymphoid hyperplasia and mood changes. The air Circulation due to different airflow resistance at different moments, so there is no