Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Mediastinal Mass and Superior Vena Cava Syndrome
Introduction
An anterior mediastinal mass is one of the most challenging pathologies an anesthesiologist may face during his or her career. To safely care for these patients, it is imperative to know the relevant anatomy of the mediastinum, understand how mediastinal pathology can compromise a patient’s respiratory and cardiovascular systems, and recognize how to prepare for and quickly intervene to treat these potentially life-threatening complications. In this chapter, we will present a case of an anterior mediastinal mass with superior vena cava syndrome (SVCS). We will discuss the important preoperative testing, preanesthetic considerations, risk stratification, and intraoperative anesthetic management. We will also present a flowchart with potential management strategies to assist in safely caring for the majority of these patients.
Case Presentation
A 30-year-old female with no significant past medical history presents to the emergency department with dyspnea, inability to lie flat, cough, and chest discomfort that has progressively worsened over the past few weeks. Clinical examination findings are notable for engorged neck veins with head and upper extremity swelling. Following admission to the hospital, a subsequent workup reveals a very large anterior mediastinal mass associated with both tracheal and great vessel compression. A malignancy is suspected, and the plan is to obtain a tissue sample for histologic diagnosis followed by surgical resection by a multidisciplinary team.
Review of the Literature
Anatomy and Pathophysiology
The mediastinum is the area within the chest bounded anteriorly by the sternum, posteriorly by the vertebral column, laterally by the two parietal pleura, inferiorly by the diaphragm, and superiorly by the thoracic inlet. Some authors divide it into four compartments: the superior, anterior, middle, and posterior compartments. The superior compartment is bound superiorly by the thoracic inlet and inferiorly by the plane extending from the sternal angle anteriorly to the lower border of the fourth thoracic vertebrae posteriorly. The anterior, middle, and posterior compartments are bound superiorly by this plane, inferiorly by the diaphragm, and are divided in the anterior to posterior direction based on the pericardium , ( Fig. 34.1 ). Others argue that because there is no true anatomic boundary separating the superior and anterior compartments, it is considered one compartment, the anterosuperior compartment, and that the mediastinum is made up of three distinct compartments: the anterosuperior, middle, and posterior compartments , ( Fig. 34.2 ).
Regardless of whether there are three or four mediastinal compartments, it is important to realize that these compartments cannot be treated as separate entities. Masses in one compartment often extend and affect structures in other compartments. Anterior masses often invade the middle compartment, and masses in the anterior and middle compartments may have similar effects. Furthermore, many of the lesions in the superior compartment originate from or extend into the anterior compartment. In addition, although the majority of complications are described for anterior mediastinal masses, masses in the middle and posterior mediastinum have also been associated with hemodynamic and respiratory collapse with induction of general anesthesia.
There are many vital structures within the mediastinum that can be affected by the presence of masses ( Fig. 34.3 ). The anterosuperior compartment contains the lower trachea, the aortic arch and its branches, the super vena cava, and the azygous vein. The middle compartment contains the heart, the carina and mainstem bronchi, the pulmonary hila, and the terminal portion of the superior vena cava. The posterior compartment contains various nerves and nerve roots, the sympathetic chain, the descending aorta, the esophagus, and the azygous vein.
Mediastinal masses can be primary or metastatic tumors , ( Fig. 34.4 ; Table 34.1 ). Metastatic tumors are relatively common, whereas primary tumors are quite rare and are often benign. The most common anatomic location and histologic type of mediastinal tumor differs by age. In children, there is an increased incidence of neurogenic tumors, particularly neuroblastomas, and masses are predominantly found in the posterior mediastinum. , In adolescents, lymphomas in the anterior mediastinum are the most common. In adults, masses are seen most frequently in the anterosuperior compartment, and are most often thymomas and lymphomas.
Table34.1
Malignant and Benign Mediastinal Tumors by Location
| Compartment | Malignant Tumors | Benign Tumors |
| Anterior | Lymphoma Mixed germ cell Seminoma Thymic carcinoma Thymic carcinoid Thyroid carcinoma |
Cystic hygroma Foramen of Morgagni hernia Parathyroid adenoma Thymic cyst Thymic hyperplasia Thymolipoma Thymoma Thyroid |
| Middle | Esophageal cancer Lymphoma Metastases Thyroid carcinoma |
Benign adenopathy Cardiac and vascular structures Cardiophrenic fat pad Cysts Ectopic thyroid Esophageal mass Foramen of Morgagni hernia Hiatal hernia Lipomatosis |
| Posterior | Neuroblastoma | Neurofibroma Schwannoma Chemodectoma Foramen of Bochdalek hernia Meningocele |
Modified from Yoneda KY, Louie S, Shelton DK. Mediastinal tumors. Curr Opin Pulm Med . 2001;7(4):226–233.
A growing mass in the mediastinum has the potential to interfere with many of the important structures contained within it and cause a variety of symptoms. When adding the physiologic changes seen under general anesthesia, even an asymptomatic patient can develop severe, and potentially fatal, complications.
Preanesthetic Assessment
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here