72 OPERATIVE TECHNIQUE. 



shielding the injured tissues by thick layers of cotton wool. Lister, on 

 the other hand; sought to destroy microbes present in the wound or 

 introduced during operation, by means of chemical substances. Lister 

 first rendered the wound aseptic and afterwards protected it by a 

 germicidal barrier. 



Let us consider the surgical dressing. At lirst Guerin did not 

 seek primary union of the wound, only attempting to reduce the 

 discharges and to avoid infection. Bleeding having ceased, he washed 

 the wound with tepid water, afterwards with a mixture of water and 

 camphorated alcohol. In some cases he sutured the wound and cut 

 the threads short, covering the parts with several layers of wadding. 

 In extensive operations on the limbs the region was enveloped in many 

 layers of wadding suitably affixed. The outer bandages were applied 

 tightly, and if during the next few days the degree of compression was 

 considered insufficient, or if the discharges penetrated the whole thick- 

 ness of the wadding, fresh bandaging was resorted to. At first the 

 dressing was left in position for twenty to twenty-five days, later it was 

 replaced at the end of twelve to fifteen days. As a rule on removing 

 the first dressing the wound was found to be granulating throughout. 

 With a second dressing left in position for eight to ten days cicatrisa- 

 tion was complete. 



To obtain primary union various modifications were made in this 

 method. Thus bleeding was more thoroughly checked, and the lips 

 of the wound carefully closed with deep sutures of some material 

 like catgut, which would gradually disappear. Despite its many 

 advantages this dressing of cotton wool concealed the state of the 

 wound. The thermometer certainly gave indications of unfavourable 

 changes, but as considerable fever sometimes occurs even when wounds 

 are doing well, time was lost, and it was not infrequently necessary to 

 remove the dressings, thus exposing the patient to danger. Further, 

 although atmospheric germs could not enter the wound through the 

 layers of cotton wool, those already there or introduced during opera- 

 tion were not destroyed, and frequently multiplied with great rapidity. 



Compared with the older dressings that of cotton wool constituted 

 an immense stride in the surgical art, but, nevertheless, its use did not 

 become general. The greatest success was reserved for Lister's 

 dressing, which was more practical and also more certain in its 

 results. 



To prevent infection Lister sought to destroy all infectious materials 

 in and around the wound as well as in the neighbouring air. Com- 

 pleting this process, he took care that the hands of the surgeon and his 

 assistants, the instruments, sponges, compresses, and all materials used 



