A surgeon's approach to thoracic disease

摘要

Thoracic surgery differs significantly from abdominal surgery for several reasons but foremost is the pleural space and ventilation. The thoracic wall, diaphragm, and respiratory muscles are responsible for creating pressure changes in an awake or anesthetized animal that cause passive movement of air in and out of the lungs. When we open the pleural space to environmental pressure by thoracotomy no passive movement of air in and out of the lung will occur, therefore the anesthetic management mustinclude assisted ventilation. Once surgery with the thorax is complete, a chest drain (thoracostomy tube) is placed to allow evacuation.of air and fluid from the pleural space so respiratory muscle can intermittently create subatmospheric intrathoracic pressure allowing the animal to breath on its own. Chest drains are tunneled a short distance under the skin (one or two intercostal spaces), and then "punched" into the pleural space while guarding thoracic structures from the tip of the drain. The drainis generally directed to lay anterior and toward the ventral aspect of the thoracic cavity but this may vary depending on the nature of the thoracic disease. Usually only one chest drain is placed but one on each side may be used for thoracic diseases such as pyothorax. Chest drains remain in place after surgery for 12 to 24 hours (sometimes longer) so that control of the pleural space is maintained should air, fluid, or hemorrhage accumulate. Occasionally, iatrogenic injury to the lung parenchyma mayoccur and be unrecognized prior to closing a thoracotomy, the chest drain with allow earlier recognition of such a problem. Prior to closure warmed sterile saline is place in the pleural space to check for air leakage during lung inflation. A Pleurivac system may be used to simultaneously evacuate air and fluid from the pleural space. This system and similar systems will quantitate fluid obtained from the pleural space but cannot quantitate air evacuated. Chest drains are removed when air no longer escapes into the pleural space and the production of fluid decreases.