Defense, qi, nutrient and blood are the component parts of normal structures and functions of the human body. After attack of a warm disease, there may successively appear relevant pathological changes, which are of certain laws. So, defense qi, nutrient and blood are borrowed to summarize syndrome types in the four different stages of a warm disease, expounding the depth of site, seriousness of condition, direction of trend in the course of the warm disease, and providing basis for treatment of the warm disease. For an acute pyogenic infection of joint, the syndromes may be differentiated according to the laws of defensive-qi-nutritive-blood phases. In the early stage of infection, there are fever and chills, headache, general pain, thin and white tongue coating, floating pulse, this indicates that the pathogen is in the defensive phase and the condition is mild.

The treatment should be clearing away heat and poison with the purgation and cool herbs as the subsidiary. As the infection develops, if there appear high fever, great thirst and profuse sweat, this indicates the pathogen is in the qi phase and the condition is severer. And if there appear abdominal distention, fullness and pain aggravated by pressure, dysphoria, delirious speech, constipation or the passage of yellow and fetid liquid feces, red tongue with yellow or gray-black coating and prickles, deep-rapid-and-forceful pulse, it is an excess-heat syndrome of the stomach and intestines in qi phases. Then the recipe with action of eliminating stasis by purging and retaining yin by urgent purgation should be taken.

If the fever gets higher, and accompanying symptoms are dysphoria, macule and papule, crimson tongue without coating, thready and rapid pulse, this indicates the pathogenic heat has been to the nutrient phase. Then, the treatment should be clearing the heat from the nutrient phase. If the condition further deteriorates, there appears disturbance of consciousness marked by indifferent expression, coma, delirious speech, carphology, this is a sign of heat invading the pericardium. Then, the drugs to clear the heart and open orifice should be added. If there are accompanying symptoms of spasm of limbs, stiff nape, convulsion, opisthotonos, trembling or deviated tongue, this is an evidence of heat engendering liver-wind. Then the drugs to soothe the liver to stop wind should be added.
   
Following the transmission of infection from the local to the whole body, there may appear symptoms of rigor, high fever, severe headache or general pain, dyspnea, delirium, madness, or even coma; hematemesis, hemoptysis, hematuria, hemafecia, ecchymosis; crimson or purplish tongue with burnt-yellow coating and prickles or without coating, rapid-surging pulse or rapid-deep-thready pulse. This indicates that the pathogenic heat has been to the blood phase, with excessive pathogen and insufficient healthy qi, and the disease is in a critical stage. Thus, the treatment should be cooling the blood to stop bleeding, and yet the herbs with the action to rescue the patient from collapse or to open the orifice should be urgently used.