RESUMEN
This article highlighted the invaluable expertise of Academician TONG Xiaolin in managing severe cases of COVID-19， thereby providing ideas for the treatment of severe and critically ill patients with SARS-CoV-2 infection by integrating traditional Chinese and western medicine. It is believed that COVID-19 belongs to the “cold dampness epidemic” in traditional Chinese medicine， which is caused by pathogenic qi of cold and dampness. The course of the disease can be divided into four stages： constraint， block， collapse， and deficiency， and the severe cases are mainly in the block and collapse stages. The pathogenesis at the block stage is described as epidemic toxins blocking the lung， which should be treated by diffusing the lung and unblocking the bowels， resolving phlegm and unblocking collaterals. The primary formula used is Zilong Xuanbai Chengqi Decoction （子龙宣白承气汤） with modifications based on individual condition. The pathogenesis at the collapse stage is described as internal block and external collapse， which should be treated by restoring yang to save from collapse， boosting qi to relieve collapse， diffusing the lung and unblocking the bowels， resolving phlegm and unblocking collaterals， usually with the formula Poge Zilong Xuanbai Chengqi Decoction （破格子龙宣白承气汤） with modifications.