What external manifestations does impaired lung qi diffusion have on the body surface?

The lung governs diffusion and dispersion, which is a concept in traditional Chinese medicine. In ancient Chinese medicine, it is said to distribute qi throughout the body, and also to transport the essence of water and grain transmitted from the spleen to the lung throughout the body, distributing defensive qi, reaching outward to the skin and hair, in order to warm and nourish the interstitial muscles, fill and nourish the skin, and regulate the interstices. As stated in Yi Xue Shi Zai Yi: "All qi of the viscera, meridians and collaterals is diffused by lung qi." In Western medicine terms, this means distributing throughout the body the nutrients necessary for human metabolism and maintaining clear airways.

So when external pathogens such as wind-cold or wind-heat are abundant and block the lung passages, lung qi fails to diffuse, meaning it cannot disperse, and respiratory symptoms appear, which also affect the delivery and coverage of qi and blood throughout the body. Therefore, after catching a cold, systemic symptoms such as fever and fatigue and weakness also occur. In a broad sense, lung qi diffusion in traditional Chinese medicine also includes areas such as the nasal cavity and throat. In ancient medical texts, impaired lung qi diffusion also mostly refers to externally contracted diseases.

Therefore, in ancient medical texts it is said: the lung governs respiration and opens into the nose, and externally corresponds to the skin and hair. Externally corresponding to the skin and hair means the lung governs the skin and hair, covering the body surface with defensive qi. When external pathogens such as cold, heat or dryness invade the human body, they first cause the skin and hair to close, resulting in body-surface lung qi being unable to diffuse. In fact, this is still because a person's lung qi is insufficient and lacks the strength to strongly resist external pathogens. Traditional Chinese medicine places the greatest emphasis on a person's vital qi and innate constitution, with the exception, of course, of pestilential diseases.

This also explains why, under the same external factors such as cold, heat, summerheat, dampness and dryness, the effects on each person differ: some people do not fall ill while others do, and among those who do fall ill, the incubation period and the severity of the condition also vary. Ancient Chinese medicine also has the concept of unfavorable lung qi, which refers to internal injury diseases causing lung qi deficiency and weak diffusion, such as lung distension and so on.