ture of the ribs with injury to the lung, air might be present in the tissues and in contact with effused blood, without any inflammation or suppuration taking place. Lister was unable to afford any full explanation of the facts until his attention was directed in 1865 by his colleague, Dr. Thomas Anderson, professor of chemistry in the university, to the researches of Louis Pasteur, who had proved that putrefaction, like fermentation, was dependent upon the presence in the air of living germs, or vibrios as they were called at first. Lister saw at once the explanation that he had been seeking. Again to quote his own words: ‘When it had been shown by the researches of Pasteur that the septic property of the atmosphere depended, not on the oxygen or any gaseous constituent, but on minute organisms suspended in it, which owed their energy to their vitality, it occurred to me that decomposition in the injured part might be avoided without excluding the air, by applying as a dressing some material capable of destroying the life of the floating particles.’ Three methods are available for depriving the air of its germs: filtration, heat, and chemical agents; Lister selected the third as the one most obviously practicable. Prior to becoming acquainted with Pasteur's work, he had practised various methods to secure cleanliness in the routine treatment of wounds, but with no great success. So soon as he determined, in the light of Pasteur's work, to attempt to destroy germs in contact with the wound, by means of a chemical agent, he selected carbolic acid for this purpose. This choice was due to his knowledge of the striking results that had been obtained at Carlisle in the treatment of sewage by this substance when used as a disinfectant. Lister's first attempts were made in the treatment of serious injuries, such as compound fractures. This class of case was at that date a peculiarly serious one, with a very high mortality due to septic infection. Lister, from an early stage of his work, realized that the causes or agents of putrefaction might be present in the injured part before the surgeon intervened, as in the case of a compound fracture, or that they might be introduced at the time of operation, as when an incision is made through unbroken skin. The successful treatment of the former class of case is necessarily much more difficult, and it is striking that he should have selected cases of compound fracture for his first attempts in the new treatment. He first used carbolic acid in the treatment of a compound fracture in March 1865; and in the following spring treated a very severe case of compound fracture in the leg with such complete success that the case practically followed the usual course seen in instances of simple fracture, i.e. there was no general illness and no suppuration. This case formed the basis of his paper in the Lancet, 1867, describing the new method of treatment of compound fracture.
Lister, in his earliest cases, used liquefied German creosote, an impure carbolic acid; this he introduced into the wound and then covered the part with a layer of lint soaked in carbolic acid. After the success obtained in the treatment of compound fractures, he used a similar method in the treatment of abscess. From this time onward he constantly extended the scope of his method and the field of his operations; but he devoted himself more especially to improving the method itself, so as to avoid the irritation produced by the crude carbolic acid. Thus he introduced carbolic oil and carbolized putty, and later he employed carbolized shellac and watery solutions of carbolic acid. From the first he insisted on the necessity of disinfecting instruments and everything else that came in contact with the wound, and he also carried out a thorough disinfection of the patient's skin in the vicinity of the wound. Further, he devoted much time and thought to devising suitable dressings, such as the well-known gauze impregnated with resin and paraffin and then dipped in a watery solution of carbolic acid. He also introduced the carbolic spray apparatus for disinfecting the air in the field of the operation, being at that time impressed with the belief that the air was a most important factor in the causation of sepsis, owing to the presence of germs in its dust. Later, the spray was dispensed with, as it was recognized that the air did not play such an important part as infection derived from the skin, instruments, dressings, &c. Nevertheless the introduction of the spray showed the extreme care which he took in devising all possible means to prevent contamination of the wound.
Lister also greatly improved the technique of operations by inventing new methods of treatment, which likewise had a profound influence in preventing septic infection. Thus he introduced the use of absorbable ligatures and of drainage tubes in the treatment of wounds. Surgeons hitherto had been in the habit of arresting haemorrhage by tying the
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