Abstract
The most commonly accepted explanation for the production of post-operative pulmonary atelectasis is bronchial obstruction, either by a mucous plug or by bronchial secretion. The obstruction of the bronchus or bronchi must be complete so that air can not enter the lung distal to the obstruction. The trapped air or gas in this obstructed part of the lung is then absorbed by the blood and so the lung collapses or becomes atelectatic.
To study this mechanism, a large variety of foreign bodies have been used to plug the bronchi in dogs such as shot, paper balls, gum arabic, 1 sponges, 2 peas, 3 ligation of a bronchus, 4 rubber balloons, 5 corks, 6 etc. Some investigators 7 have even used tenacious secretions removed from the bronchial tree of a patient with massive atelectasis. It seemed to us that, rather than introduce foreign bodies into the bronchi of dogs, the condition in the human would be simulated more nearly if a mucous plug or tenacious secretion could be produced in the bronchi by irritation. It was found that mustard oil 8 was admirably suited for this purpose.
The dogs were first anesthetized, usually with sodium amytal. Bronchoscopy was performed and the bronchial tree examined to make certain it was normal. A small cotton pledget moistened with mustard oil was then introduced through the bronchoscope into the desired bronchus and held there for 2 or 3 minutes. This area was examined subsequently at frequent intervals through the bronchoscope.
It was found that a bronchial plug of the type shown in the illustration was formed usually in about 24 hours. With one exception there was little reaction in the rest of the bronchial tree. This type of plug was found to extend deep into the finer ramifications and was frequently over an inch in length.
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