Abstract
The following experiments furnish a striking illustration, suitable for classroom demonstration, of the influence of temporary ischemia on the local resistance to infection:
Two or three slight cuts are made on the upper or middle third of each ear of a rabbit, by closely clipping the hair from the dorsal surface of the ear; lifting with forceps a small fold of the skin, and snipping this fold away with scissors. This makes small wounds of about 4 by 7 mm., usually without hemorrhage. The wounds may then be smeared with active agarcultures of staphylococcus or pyocyaneus; or they may be left without artificial infection. Within a few minutes after making the wounds, 1 c.c. of epinephrin, 1 : 1000, is injected into the root of one ear, close to the entrance of the vessels. This produces an intense ischemia of the entire ear, persisting for several hours. 1
From the following day, the two ears present a striking difference in appearance: The wounds on the normal ear show signs of healing, even if they were severely infected. The wounds on the ear that had been rendered anemic appear much more inflamed, and may be covered with pus, and a perforating ulcer may have started. This is shown in the adjoining photograph, taken 24 hours after inoculation with a virulent staphylococcus culture, recently prepared from a human throat: The epinephrin ear (the right) shows the perforation of the ear by the infection; whilst in the left ear, no inflammation is visible on the inner side, although the ear had been equally wounded and inoculated, but not treated with epinephrin. These differences persist in the further course; the ear that had received epinephrin healing more slowly than the other ear.
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