The structures which compose the chest cage —i.e., skin, fat, bones, and muscles—may be affected with the same diseases which can occur to such tissues anywhere else in the body. For example, infections or tumors may involve any of these parts. The treatment is the same as for similar diseases elsewhere.
However, when a surgical procedure involves opening into the lung cavities, this is of major import. Here the vacuum in the cavity around the lung is lost, and the lung collapses by its own elasticity. The pleural “space” is then a real space, filled with air. When the lung collapses it no longer performs its respiratory function; the other lung must acquire all the oxygen the body needs.
When the lung collapses and air fills the pleural space, the condition is known as pneumothorax (air-thorax). When this occurs with operation it may be called surgical pneumothorax. The same may occur with injuries to the chest wall, known as traumatic pneumothorax. With certain diseases, such as air blebs on the lung, there may be spontaneous rupture of the lung and a communication established between the respiratory tree and the pleural space which fills the space with air; this is spontaneous pneumothorax. In the treatment of tuberculosis, air is sometimes injected into the pleural space to collapse the lung and place it at rest; this is artificial or induced pneumothorax. In such case, the pneumothorax is maintained by regular repeated injections of air.
After operations on the chest where a pneumothorax results, drainage and/or suction tubes are left in place through the chest wall incision to re-expand the lung and assure drainage of any serum or blood which collects in the pleural cavity. Commonly this is by underwater suction, where the aspirated air passes through water to preclude germs from ascending through the tubes, and to obviate any loss in the constant vacuum.
Incisions through the chest wall are calculated according to the underlying organ to be approached. Figure shows the commoner incisions on the chest wall. Most often the incision will be between two ribs. In some instances a rib is partially removed to gain entrance into the chest; its outer covering, the periosteum, is left, from which new bone regenerates. Any operation involving entry into the chest cavity is known as thoracotomy. Sometimes the chest incision is combined with an abdominal incision to approach structures of the lower chest, such as the lower section of the esophagus.
Some infectious diseases may proceed unhalted in their course to pus formation in the pleural cavity. This is known as empyema. Similarly, abscesses may develop within the lung tissues, called pulmonary abscess. In certain diseases fluid may collect in the pleural space and between the lobes of the lungs, which is called pleural effusion, or interlobar effusion, or hydrothorax. Likewise, blood may collect in these spaces after injuries (hemothorax). Any of these conditions may demand drainage. This is accomplished occasionally by an open incision, but more often the simpler procedure of introducing the drain through a puncturing instrument which is inserted through the chest wall is employed. Usually local anesthesia is adequate.
Pneumothorax in treatment of tuberculosis to place the lung at rest has been mentioned. However, in many cases, complete collapse does not occur due to adhesions between the inner chest wall and the lung covering. These bands, the result of the disease or previous thoracotomy, prevent the lung from contracting by its own elasticity. To allow complete collapse, these bands have to be severed, the procedure known as pneumolysis. This is done by inserting a lighted instrument, the thoracoscope, through the chest wall, through which the adhesive bands may be directly visualized and cut with cautery current. This is done under local anesthesia.
Another means of setting the lung partially at rest for the treatment of tuberculosis is by paralyzing the diaphragm on the affected side. This is done by disrupting the nerve supply which comes through the phrenic nerve. The nerve is dissected out through a small incision at the lower neck on the diseased side. The nerve may be severed or partially removed for permanent paralysis of half the diaphragm, but more often it is just crushed, which temporarily accomplishes the same purpose. With the crushing procedure, after several months the nerve will regenerate and the diaphragm will again function. If continued partial collapse is desired, the procedure may be repeated. This operation is called phrenic crush or phrenoneurolysis.
Another operative procedure used in the treatment of tuberculosis is thoracoplasty. Here the lung is set at rest by producing partial collapse by removing a portion of the supporting framework of the chest wall. The ribs are removed over the diseased portion of lung so that the chest wall collapses. As many as seven or eight ribs may be removed, but the procedure is done in stages, usually with removal of three or four at each operation. The outer covering of the rib is left so that the bone will regenerate in the collapsed position. This procedure is indicated when it is evident that there is little hope of controlling the disease without a permanent collapse. The chest, of course, remains deformed, but often this is a life-saving procedure. Formerly this was a common procedure in tuberculosis treatment but now is less commonly necessary.
Needless to say, when a lung or a part of the lung is collapsed, the remaining normal lung has to perform the entire respiratory function and its work load is increased.
Congenital anomalies of the chest wall are not common. Asymmetry of the chest and various deformities of the ribs may occur but usually they are not of significance. One fairly common and significant abnormality is funnel chest or pectus excavatum. In this condition there is a marked depression in the middle front of the chest. The normal slight depression over the breast bone (sternum) is exaggerated. All degrees of this condition may occur, even to an extent where the sternum almost touches the backbone. The usual concern is over the unsightly deformity, but in severe cases the heart may be displaced to the left and respiration and circulation impaired. This condition is amenable to operation, wherein the sternum is detached from the cartilage joining it to the ribs and elevated to a normal position. Cartilage and bone transplants, or grafts, may be utilized.