Thoracic surgery is being performed on patients with more severe pulmonary disease than in earlier years. Previous exclusion criteria for undergoing general anesthesia now are considered overly conservative.
Because the mortality rate of untreated lung cancer approaches 100%, it is difficult to assign definitive exclusion criteria for lung resection. Parameters used to predict patients at increased risk for postoperative complications include forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), split lung functions, and exercise tolerance.
Patients undergoing thoracic surgical procedures often have preexisting pulmonary and cardiac disease.
The preoperative symptoms of dyspnea, shortness of breath, and hoarseness of voice may be related to thoracic tumor pathology. Possible etiologies include superior vena cava obstruction, mediastinal mass, tracheal compression, tracheomalacia, and malignancy. Anesthetic management should include an adequate preoperative evaluation to assess extent of disease, severity of symptoms, and effects of supine positioning on respiratory and cardiac function.
One goal of preoperative preparation is to improve pulmonary function by use of bronchodilators for reactive airway disease, antibiotics for infection, and education to promote the cessation of smoking. Smoking should stop at least 4 to 8 weeks preoperatively.
Routine diagnostic procedures that are performed to confirm and evaluate the extent of pulmonary and thoracic disease include bronchoscopy, mediastinoscopy, and video-assisted thoracoscopic surgery (VATS).
The anesthetic plan should be coordinated with the surgeon and support staff to limit perioperative risk. In high-risk patients, anesthesia may proceed with a slow, controlled, and staged induction to cease if respiratory difficulties ensue.
Lateral decubitus position has a negative impact on the physiology of ventilation and circulation and is associated with position-related injuries.
Fiberoptic bronchoscopy is the most reliable method for ascertaining correct positioning of the double-lumen endotracheal tube and assuring pulmonary toilet.
When using single-lung ventilation, the anesthesiologist should be especially alert to problems with ventilation or oxygenation. Most problems are related to malposition of the double-lumen tube. Once proper position of the tube is confirmed, management strategies include (1) increased oxygenation to dependent lung (positive end-expiratory pressure [PEEP], increased tidal volume [VT], increased Fio2), (2) increased oxygenation of blood flowing to the nondependent lung (continuous positive airway pressure [CPAP], intermittent ventilation), (3) decreased blood perfusion to nondependent lung (discontinue drugs that inhibit hypoxic pulmonary vasoconstriction [HPV], ligature to pulmonary artery [PA]), increased oxygen content of blood (transfusion, improve Svo2), and (4) increased perfusion of the dependent lung (increased cardiac output and administer a pulmonary vasodilator).
Hypoxic pulmonary vasoconstriction (HPV) is a homeostatic mechanism that limits perfusion of unventilated nonoxygenated atelectatic alveoli, thereby decreasing the shunt admixture. HPV is activated by decreased alveolar oxygen tension, but is inhibited by certain anesthetic agents and vasodilators.
Volume reduction surgery and other sophisticated intrathoracic operations require extraordinarily careful and complex planning and constant vigilance to maintain adequate ventilation, oxygenation, and hemodynamic stability.
Postoperative management after thoracotomy or thoracoscopy is directed to the delicate balance between pain relief and respiratory depression associated with opioids. Epidural analgesia represents ...
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