In order to explore the application ideas of classical prescription Sini Decoction（四逆汤） and its series decoctions in the original work

expand the modern application scope of the prescription

the "typical-atypicalchange"model was cited for analysis. The typical application of Sini Decoction is the cold syndrome of Shaoyin disease

which was seen in the syndrome of deadly cold four limbs with yang deficiency due to yin excess. It was hypovolemic shock in the modern medicine. Atypical application was not seen in deadly cold

but seen "diarrhea with undigested food in the stool"for prevention with Sini Decoction

or seen the "deep pulse"need warmth. Baitong Decoction（白通汤）

Tongmai Sini Decoction（通脉四逆汤）

Fuling Sini Decoction（茯苓四逆汤）

Zhenwu Decoction（真武汤）

etc. were the modified application of Sini Decoction.