Trachea emergency situation, and this is a cricothyrotomy. Tracheal agenesis, is a rare birth defect in which the trachea fails to develop. The defect is usually fatal though sometimes surgical intervention has been successful. A tracheoesophageal fistula is a congenital defect in which the trachea and esophagus are abnormally connected. Sometimes as an anatomical variation one or more of the tracheal rings are completely formed. These "O" rings are smaller than the normal C-shaped and can cause narrowing of the trachea resulting in breathing difficulties. An operation called a "slide tracheoplasty" can be performed which opens up the rings and rejoins
Traditional Chinese medicines derived from the human body were successfully making quasi-empirical preparations of active substances with androgens and estrogens, a technique that modern biochemists did not develop until the early 20th century. The physician William C. Cooper and the sinologist Nathan Sivin (1973) chose what the Chinese call "rényào" 人藥 "human drugs" as a pilot experiment sample for pharmacologically analyzing the efficacy of drugs used in TCM. In contrast to many traditional Chinese plant, animal, and mineral pharmaceuticals with uncertain active constituents, the chemical composition of the human body and parts is well known, and "their therapeutic effectiveness, or lack of it, can be objectively, if approximately,