<unk><unk>  (usually simply referred to as<unk> , an invasive medical procedure, is the placement of a flexible plastic catheter into the<unk>  For millennia, tracheotomy was considered the most reliable (and most risky) method of<unk><unk> . By the late 19th century, advances in the sciences of anatomy and physiology, as well as the beginnings of an appreciation of the germ theory of disease, had reduced the morbidity and mortality of this operation to a more acceptable rate. Also in the late 19th century, advances in endoscopic instrumentation had improved to such a degree that direct laryngoscopy had finally become a viable means to secure the airway by the non-surgical orotracheal route. Nasotracheal<unk>  was not widely practiced until the early 20th century. The 20th century saw the transformation of the practices of tracheotomy, endoscopy and non-surgical<unk><unk>  from rarely employed procedures to essential components of the practices of anesthesia, critical care medicine, emergency medicine, gastroenterology, pulmonology and surgery.
History of tracheal intubation
History of cardiopulmonary resuscitation
History of general anesthesia
History of invasive and interventional cardiology
History of neuraxial anesthesia
History of chemical warfare
History of tuberculosis
History of aspirin