152 OPERATH'E TECHNIQUE. 



be grasped with the fingers, drawn forward, freed from the nerves 

 which accompany it, and, on account of the collateral circulation, 

 doubl}- ligated. To prevent the \essel tearing through at the seat of 

 ligation in consequence of continued tension it is divided between the 

 ligature, and the ends allowed to retract. Care must be taken in 

 separating the recurrent nerve and in cleansing the wound, as 

 mechanical injury to the nerve or irritation produced b}' local suppura- 

 tion may be followed b}- paralysis and "roaring." Other methods like 

 continued compression of the artery and closure of the skin with 

 sutures have been recommended. Compression might in isolated cases 

 be followed by haemostasis, but closure of the skin wound is dangerous. 

 Experiment shows that a large hasmatoma usuall}' develops, and 

 pressure on the trachea may become so severe as to cause suffocation. 

 Should the carotid be damaged the patient should be kept under 

 observation. The accident, however, is rare. 



Sometimes a small artery in the region of operation is divided, and 

 gives the impression of the carotid having been injured. Injury of 

 the vagus or sympathetic nerve seldom occurs. Perforation of the 

 trachea can only be caused by gross carelessness, but if opened suffi- 

 ciently for blood to enter the lungs, it might give rise to troublesome 

 symptoms. 



The low or even negative blood-pressure in the jugular vein 

 renders that vessel specially convenient to bleed from, but at the 

 same time entails a certain danger of air being aspirated into it, 

 with suddenly fatal result. As a rule, even if the vessel be not 

 compressed below the incision, sufficient blood flows from above to 

 preserve a slight positive pressure. Should this pressure from above 

 fail, however, as would happen were the vessel compressed . above 

 the wound, the down-rushing column of blood would aspirate air into 

 the vessel, and a gurgling or bubbling sound be heard, indicating 

 to an experienced operator the serious character of the accident. 

 A deep inspiration is also followed b}' so rapid a rush of blood 

 towards the heart as to dangerously favour the in-draught of air 

 through the wound. Such accidents cannot well occur while the 

 escaping stream of blood is well marked ; they onl}- happen after 

 it slackens or ceases. Immediately the sound is heard the vein 

 should be compressed as low down in the neck as possible, and 

 attempts made to expel the air by strokmg the vein from below 

 upwards. After operation animals not infrequentl}' lean against the 

 manger or on the head-collar rope, and ma}- thus compress the 

 vein above the wound, with the result that air obtains entrance. 

 For this reason the wound should alwavs be sutured. 



