164 THE HEAD AND NECK 



vigorously, he may slit the posterior wall and open into the 

 subjacent oesophagus. 



The operation of High Tracheotomy is performed through 

 the interval between the cricoid cartilage and the isthmus of the 

 thyreoid gland. It is usually carried out for some form of 

 laryngeal obstruction, and has been labelled an " emergency " 

 operation. There is, however, no necessity for excessive hurry, 

 because, provided that the patient is not further embarrassed 

 by the administration of a totally unnecessary anaesthetic, 

 respiration can always be restarted after the trachea is opened. 

 During the operation the neck is well extended over a small 

 sandbag or cushion, and is held in position in the middle line 

 by an assistant until the tracheotomy tube has been inserted. 

 In this way the trachea is steadied and drawn tight, for its 

 rounded shape renders it liable to be pushed aside, especially 

 if the head is not held absolutely in the middle line, in which 

 event the oesophagus may be opened by mistake. The incision 

 may be either vertical or horizontal as it divides the skin and 

 superficial fascia, but it should pass vertically between the two 

 anterior jugular veins. On account of the obstruction to 

 respiration these veins are engorged and may almost touch one 

 another. The investing layer of the deep fascia is incised vertic- 

 ally, and if the subjacent sterno-hyoids are close together they 

 must be retracted. The surgeon now feels for the cricoid 

 cartilage and the isthmus of the thyreoid gland, and when these 

 guides have been identified he makes a transverse cut through 

 the pretracheal fascia just below the cricoid cartilage. The 

 isthmus of the thyreoid gland, with its fascial sheath derived 

 from the pretracheal fascia, can now be retracted downwards, 

 exposing the upper rings of the trachea. A vertical incision is 

 then made in the exposed part of the trachea from below up- 

 wards, the back of the knife being directed to the isthmus of the 

 thyreoid gland to avoid injuring the anastomosing terminal 

 branches of the superior thyreoid arteries on its upper border. 

 If sufficient room is not obtained by this method, the cricoid 

 cartilage may be divided, or the isthmus of the thyreoid gland 

 may be cut through. It is said (Treves) that there is no danger 

 of thyreoidism by absorption from the unligated portions of 

 the gland. When the tube is inserted care must be taken not 

 to pass it down the outside of the trachea amongst the depressor 

 muscles nor between the fibro -elastic membrane, in which the 

 cartilaginous rings are embedded, and the mucous lining. 



