6After all thymic veins are divided, the dissection is carried along the anterior pericardial surface into the mediastinum. The thymus generally remains encapsulated and is separated without difficulty from the pericardium. If necessary because of adhesions, a portion of pericardium can be removed along with the gland at the site of the adhesion. As the dissection continues deeper into the mediastinum, the bulging pleura on either side commonly obstruct the surgeon's view. With some coordination, the anesthesiologist can intermittently suspend ventilation for a reasonable period to allow better visualization deep into the mediastinum. Using a Kitner dissector or a larger sponge dissector, the surgeon can easily depress the great vessels and allow direct visualization into the aorto-pulmonary window for complete removal of the thymus in this vicinity. Some direct contributing blood vessels can be identified in the form of veins draining into the superior vena cava on the right or small branches of the internal mammary veins from the left or right. These can be dealt with using electrocautery, although care should be taken to avoid injury to the phrenic nerves. Because patients with myasthenia gravis are generally not given a paralytic agent during the course of anesthesia, the proximity of the phrenic nerves will be apparent when electrocautery is used in the mediastinum. Injury to the nerves is exceedingly rare as long as the electrocautery is on a low setting and the point of application is always adjacent to the thymus and not wide in the mediastinum. In most cases, the thymus gland is removed as a complete gland with both upper poles and both lower poles intact. In these circumstances, careful inspection of the remaining tissue in the mediastinum is performed to identify any possible congenital thymus tissue remaining after the removal of the gland. Any suspicious bits of fat in the mediastinum are removed and, if necessary, sent for frozen section to ascertain whether or not they contain thymic tissue. This verification is advised in the surgeon's early experiences, but becomes less important as the techniques become more familiar. A red rubber catheter is placed into the mediastinum, and the deep layers of the incision are closed around it. The catheter is pulled out slowly during a sustained positive-pressure breath, and the skin closure is completed. If either pleural space was entered, the entry should be enlarged to allow evacuation of the pleural space with the red rubber catheter. The skin is closed with a subcuticular suture of absorbable material and Steri-strips. The patient is then extubated and taken to the recovery room for a follow-up upright chest x-ray. The presence of a small pneumothorax does not require remedial action, because the air will be absorbed within a few days.