The Thoracic Window

Abstract

Direct observations of activity in the lungs and heart have always been complicated by the fact that artificial respiration has been required to keep the animal alive. The results of the observations were often vitiated by the lung movements and consequent difficulty of maintaining a focus when microscopic observations were made.

Hall 1 described a method in which the isolated lung was studied by transillumination. The method was complicated and observations were limited to a rather short survival period. Later, Wearn 2 developed a much simpler method in which the animal was not exposed to excessive surgery. The tip of a lower lobe of the lung was used. Illumination was secured by a light directed through the diaphragm. Observations were made through the thinned thoracic wall. Intratracheal insufflation was used. The field for observation was definitely limited to a small area in the lowest portion of the lung.

The thoracic window is another method of making direct observations not only of the lungs and heart grossly, but also microscopically. Artificial respiration is not needed. The animal (cat or rabbit) is thoroughly anesthetized. An oval section of skin is removed from the anterior aspect of the chest. The skin remaining on the thorax −is separated from the underlying muscles. Artificial respiration is begun when the chest is opened. Several ribs are resected on each side at a point about midway between the sternum and vertebral column. After removal of the ribs and sternum a hole is punched through the chest wall out through the skin. A catheter is then drawn through this opening, the end resting inside the chest cavity.