14 Anesthesia for Patients with Mediastinal Masses Chih Min Ku Introduction .................................................................................................................. 201 Anatomy and Pathology ............................................................................................... 202 Clinical Presentation .................................................................................................... 202 Preoperative Evaluation ............................................................................................... 203 Surgical Approaches .................................................................................................... 203 Preoperative Treatment ................................................................................................ 203 Anesthetic Management ............................................................................................... 203 Complications and Risk Factors .................................................................................. 205 Anesthesia for Mediastinoscopy .................................................................................. 205 Summary ...................................................................................................................... 206 Clinical Case Discussion .............................................................................................. 207 Key Points • A careful anesthetic plan that is not irreversible is likely to result in a good outcome. • Patients with anterior mediastinal masses can develop major airway and cardiovascular compression under gen- eral anesthesia, which can be fatal. Introduction • Patients who are symptomatic or have significant compres- sion of these vital structures on CT scans are likely at high Mediastinal masses are an uncommon entity. They constitute risk. a heterogeneous group of benign and malignant tumors. The • Where possible, diagnostic procedures should be under- anesthesiologist may provide perioperative care to patients taken under local anesthesia. undergoing diagnostic and therapeutic procedures. They can • Understanding the relation of the mediastinal mass to present formidable challenges as mediastinal masses, espe- vital cardiorespiratory structures, careful preoperative cially those located in the anterior mediastinum, can cause assessment of the patient, discussion with the surgeon, perioperative morbidity and mortality by causing major air- meticulous planning, and preparation for possible peri- way and vascular compression, which may be exacerbated operative complications related to compression of the under general anesthesia. There are numerous case reports of major airways and vascular structures are key to success- fatal or near fatal complications associated with anesthesia for ful management. patients with anterior mediastinal masses [1–5]. Understand- • Useful strategies to consider include awake fiberoptic intu- ing the nature of the mediastinal mass in relation to vital struc- bation, maintenance of spontaneous ventilation, avoidance tures, its pathophysiology, careful preoperative assessment of of muscle relaxants, intubation distal to the airway com- the patient, discussion with the surgeon, and being prepared pression, positioning changes, immediate availability of for management of cardiorespiratory complications related to rigid bronchoscopy, and elective cardiopulmonary bypass compression of the trachea and vascular structures are key to in extreme cases. successful management. P. Slinger (ed.), Principles and Practice of Anesthesia for Thoracic Surgery, 201 DOI 10.1007/978-1-4419-0184-2_14, © Springer Science+Business Media, LLC 2011 202 C.M. Ku Anatomy and Pathology Table 14.1. Masses in the mediastinal compartments. Superior Retrosternal thyroid The mediastinum can be divided into four compartments: supe- Thymoma rior, anterior, middle, and posterior (Fig. 14.1). The mediasti- Anterior Thymoma Lymphoma num is bound by the thoracic inlet superiorly, the diaphragm Germ cell tumor inferiorly, mediastinal pleura laterally, sternum anteriorly, and Thymic cyst the vertebral column posteriorly. The superior mediastinum Parathyroid adenoma extends from the thoracic inlet to a plane extending from the Middle Bronchogenic cyst sternomanubrial junction to the inferior aspect of the fourth Cardiac/vascular structure Benign adenopathy thoracic vertebra. The anterior mediastinum is bound anteri- Lymphoma orly by the sternum and posteriorly by the pericardium. The Metastases middle compartment is bound anteriorly and posteriorly by Posterior Esophageal mass the pericardium. The posterior mediastinum extends from the Hiatal hernia posterior pericardium to the anterior longitudinal ligament Neurogenic tumor Spine lesions [6]. Some authors divide the mediastinum into three compart- ments [7, 8]. Table 14.1 shows the typical masses in the vari- ous mediastinal compartments [6, 8]. Most masses are located in the anterior mediastinum. In adults, the common patholo- gies include thymoma, lymphoma, and germ cell tumor. In the Clinical Presentation pediatric population, lymphoma, PNET, and neuroblastoma are more common [9]. Tracheobronchial obstruction, superior vena cava syndrome, Anterior mediastinal masses are more likely to cause right heart and pulmonary vascular compression, and sys- severe cardiorespiratory problems due to their proximity and temic syndromes, e.g., myasthenia gravis and thyroid disease relation to the major airway and cardiovascular structures. are some of the common presentations of mediastinal masses Any compressive effects can be exacerbated under general [10]. The patient can also be asymptomatic. anesthesia. Patients with tracheobronchial obstruction may complain of dyspnea, noisy breathing, nonspecific cough, and chest discomfort. These symptoms may be worse in certain posi- tions, especially the supine position. They may find lying in certain positions more uncomfortable. Signs may include tachypnea, stridor, rhonchi, and decreased breath sounds, which may also be positional in nature. Physical examina- tion is usually unremarkable. The severity of a patient’s respiratory symptoms may not correlate with the degree of airway obstruction. Patients with severe respiratory symp- toms may have significant decreases in tracheal cross-sec- tional area [11]. However, asymptomatic pediatric patients have developed airway obstruction during anesthesia [12– 14]. Children may present with symptoms of airway obstruc- tion earlier than adults because they have a smaller tracheal diameter and small decreases in tracheal diameter result in large decreases in cross-sectional area and increases in air- way resistance [10]. Superior vena cava syndrome, due to obstruction of venous drainage in the upper thorax, may present as dyspnea, CNS symptoms like headache, visual disturbance, altered menta- tion, dilated collateral veins in the upper body and edema of the face, neck, and arms. Right heart and pulmonary vascular compression can present as dyspnea, syncope during a forced Valsalva maneuver [15], arrhythmias, and cardiac murmur. Symptoms may mimic those of tracheobronchial obstruction. Hence it is important to look for the relation of the mass to the Fig. 14.1. Anatomic location of the four compartments of the medi- tracheobronchial tree, right heart, and pulmonary vasculature astinum (reprinted from Warren [6] with permission). in the radiology scans. 14. Anesthesia for Patients with Mediastinal Masses 203 Preoperative Evaluation Preoperative Treatment The most important aim of preoperative investigation is to Patients with mediastinal masses causing significant respiratory identify the size, the relations of the mediastinal mass to the or cardiovascular compression are at high risk of cardiopul- tracheobronchial tree and vital vascular structures, and the monary collapse under general anesthesia. They may benefit location and extent of any compressive effects. from preoperative treatment of the mediastinal mass with ste- This is best done by radiological studies, mainly chest roids, chemotherapy, or radiotherapy, in order to shrink the radiographs and CT scans. CT scans of the thorax provide tumor and alleviate the obstruction [11, 27–30]. Preoperative accurate assessment of the tumor, its nature, size, extent, radiation therapy due to severe clinical or radiological find- location, relations to the tracheobronchial tree and major ings has been associated with a decrease in postoperative cardiovascular structures, and airway diameters [16]. respiratory complications [31]. However, tumor shrinkage They are most useful for determining the precise level and can affect the accuracy of a histological diagnosis and cause extent of tracheobronchial or cardiovascular compression, diagnostic confusion. There is considerable controversy over and this information is essential for formulating the anes- the role of pretreatment. It has been reported that tissue diag- thetic plan. nosis was not affected if biopsies were taken within 72 h of MR imaging is not used routinely. However, it is useful in starting treatment [28]. Hack et al. found that a clear diagno- the diagnosis of neurogenic and vascular lesions, especially sis was made in 95% of children considered high risk who when the use of contrast material is contraindicated. were given steroids prior to diagnosis [29]. Ferrari et al. Transthoracic echocardiography can be considered if there believe that pretreatment affects accuracy of histological is any suspicion