74 METHODS OF ESTABLISHING GASTRIC FISTULAE. [BOOK II' 



of digestion might not be lost during the intervals between his observa- 

 tions. 



" This method, as improved by Bernard, is the one usually employed. 

 Bernard's cannula consists of two tubes, each of which has at one end 

 a broad flange. One tube screws into the other, so that the distance 

 between the two flanges can be altered at will. This is effected by 

 means of a key which fits on two projecting points in the inner tube and 

 turns it round, while the outer one is held fast by the fingers. The 

 advantage of this form over a simple tube with a shield at each end is, 

 that the cicatrix of the wound often thickens in healing, and if the tube 

 is not proportionately lengthened the outer plate presses on the skin and 

 causes ulceration. The disadvantage of Bernard's cannula is, that it is 

 too small to allow the interior of the stomach to be conveniently observed, 

 and also, I think, that the edge of the wound comes into contact with 

 the screw of the inner tube, and not with a smooth surface. These 

 disadvantages may be readily obviated by increasing the diameter of the 

 tube and the width of the flange, and adapting a key to the projecting 

 points, by which the outer tube may be placed in the stomach and turned 

 round as necessary. Such a cannula is represented in Fig. 6. 



FIG. 6. CANNULA FOE GASTRIC FISTULA. 



Operation 



" Give the dog a hearty meal, so as to distend its stomach 

 for "gastric com pl ete ty an( * ma ^e it lie close against the intestinal walls 1 , 

 fistula Anaesthetize the animal by chloroform 2 , taking care that 



the vapour is mixed with a sufficient proportion of air. 

 Lay it on its back on the table, shave off the hair from the epigastric and 

 hypochondriac regions, and remove the hairs carefully by a sponge, so as 

 to prevent the risk of their getting into the peritoneal cavity. Make a 

 vertical incision about an inch and a half to one side of the tinea alba, 

 preferably to the left, and parallel to it, extending downwards from the 

 lower edge of the costal cartilages to a distance somewhat less than the 



1 Heidenhain, who has had great experience in the establishment of gastric fistulae, 

 prefers to operate upon fasting animals; his advice appears to the author to be un- 

 questionably sound. 



2 It is preferable to anaesthetize the animal by a subcutaneous, or still better by an 

 intravenous injection of morphia. Heidenhain, who adopts the latter plan, finds that a 

 medium sized dog requires the injection of 4 c.c. of a 2 per cent, solution of morphia 

 (=0*08 grm. of morphia). 



