Chapter 96

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1642 PART 5 ■ Anesthetic, Surgical, and Interventional Procedures: Considerations Thoracoscopic Mediastinal Biopsies In the pediatric patients of various studies, thoracoscopic biopsy of mediastinal masses has been demonstrated to be safe and effective. 4,9 Thoracoscopic mediastinal biopsy is contraindicated, however, in children in whom carinal and subcarinal compression from the anterior mediastinal mass can be demonstrated. For these situations, percutaneous biopsy with local anesthesia only or 24 hours of intravenous steroids are recommended. 10–13 Alternatively, a Chamberlain procedure in a semiupright position under local anesthesia, with spontaneous ventilation, can be helpful in patients in whom a needle diagnosis of Hodgkin disease (HD) is unable to be obtained. 12 A single case has been reported in which radiation was administered to a limited area of the tumor before the initial biopsy was performed. A diagnosis was established based on tissue from the shielded area after the main mass had decreased in size. 14 To minimize morbidity and mortality in those children undergoing a biopsy of a mediastinal mass the following have been recommended: a tracheal diameter of at least 50% of normal and a peak expiratory flow rates of at least 50% of predicted value. 12 Deviation from these standards may result in loss of the airway or hemodynamic collapse while undergoing induction for a general anesthetic with subsequent mortality. Thoracoscopic Tumor Resections of the Mediastinum Thoracoscopic resection of mediastinal masses in children has been limited. There have been reports of resection of benign neurogenic tumors of the posterior mediastinum in adults and a few children. 15–16 In a more recent study by Lacreuse et al., the authors examined the role of thoracoscopy in the resection of posterior mediastinal tumors that were neurogenic in origin: ganglioneuroma, ganglioneuroblastoma, and neuroblastoma. 17 The procedures had minimal complications, including two chylothoraces that improved with conservative management and one conversion to an open thoracotomy. The authors felt thoracoscopic resection is a feasible, safe, and efficient procedure, as it allows for improved visualization of the tumor and its anatomic connections and resection can be as complete as an open procedure without having to complicate the operative technique in the same operating time. Mediastinal Neoplasms In general, these malignancies are separated into groups on the basis of location within the mediastinum, including the anterior, middle, and posterior regions of the mediastinum; for purposes of this discussion, the superior region of the mediastinum is grouped with the anterior region (Table 96–1). The relative incidence of the common mediastinal neoplasms is given in Table 96–2. Although lymphangiomas are not mediastinal neoplasms per se, they have important clinical issues as masses in the mediastinum and will be discussed in this section. Hodgkin Disease Lymphoid tumors which include HD and non-Hodgkin lymphoma (NHL) account for the highest percentage of mediastinal masses in children. 18 The majority of patients with Hodgkin disease will be older than 17 years; 11% are 11 to 16 years and 4% are younger than 10 years. Children who are diagnosed at TABLE 96-1. Different Types of Mediastinal Neoplasms, by Region Within the Mediastinum Anterior a Middle Posterior Thymoma Non-Hodgkin Ganglioneuroma lymphoma Thymic carcinoma Hodgkin Ganglioneuroblastoma lymphoma Non-Hodgkin Pericardial Neuroblastoma lymphoma teratoma Hodgkin lymphoma Cardiac rhab- Pheochromocytoma domyoma Teratoma Lipoblastoma PNET Germ cell tumor Lipoblastoma Lipoblastoma PNET = primitive neuroectodermal tumor. a Anterior includes the anterior and superior regions. an age of less than 16 years have the best prognosis. Clinically, cervical, mediastinal, axillary, and inguinal lymphadenopathy are noted in 80%, 50%, 33% and 5% of the patients, respectively; some children will also have symptoms of weight loss, fever, and night sweats, which portend a worse prognosis. The treatment of this disease is nonsurgical, consisting of chemotherapy and radiotherapy. The challenge posed to the surgical and anesthesia teams is how to safely obtain pathologic tissue to confirm the diagnosis and determine the histologic subtype of HD. As a high percentage of patients will have a concurrent mediastinal mass, the risk of a major intraoperative complication of cardiorespiratory collapse is potentially very high. To avert this risk, a series of preoperative tests can be performed: echocardiography, chest CT scan, and pulmonary function tests. Shamberger et al. used the cross-sectional area of the trachea on CT scan scanning to predict anesthetic complications and used it to determine who would be a candidate for local anesthesia versus general anesthesia. 19 Hack et al. found that a tracheal crosssectional area of
CHAPTER 96 ■ Thoracic Surgery: Surgical Considerations 1643 Figure 96-1. Computed tomography scan (axial) of the chest of a patient with an anterior mediastinal mass related to Hodgkin disease. The mass is projecting in the left hemithorax and is shifting the mediastinal structures into the contralateral chest. In addition, there is extension of the mass into the soft tissues of the anterior chest and sternum. The most significant predictor of anesthetic complications appears to be a clinical finding of stridor and/or positional dyspnea; in these patients, general anesthesia should be avoided and a peripheral lymph node which can be biopsied under local anesthesia should be sought. 20–21 Non-Hodgkin Lymphoma NHL is the third most common malignancy in childhood. There are three types of NHL that occur in children, making up >90% of diagnoses: lymphoblastic lymphoma, small–noncleaved-cell (Burkitt and non-Burkitt) lymphoma and large-cell lymphoma. Various immunodeficiency states are associated with NHL: human immunodeficiency virus, Wiskott-Aldrich syndrome, Bloom syndrome, ataxia telangiectasia, severe combined immunodeficiency disease, X-linked lymphoproliferative syndrome, and organ transplantation. Clinically, NHL presents abruptly and can progresses rapidly, having wide spread lymph node and extralymphoid involvement. Mediastinal involvement is predicted by the type of NHL with lymphoblastic lymphoma presenting most commonly in the anterior mediastinum in 50 to 75% of cases. In addition, some types of NHL, such as small–noncleavedcell (Burkitt’s and non-Burkitt’s) lymphoma, can have a tumor doubling time of 24 hours, making rapid diagnosis of paramount importance to avoid the complication of tumor lysis syndrome (hyperuricemia related to rapid cell death). The approach to the management of an anterior mediastinal mass in NHL is similar to HD; however, there are often other options to safely obtain a tissue diagnosis with NHL using local anesthesia which should be considered. These include bone marrow biopsy, aspiration of thoracic effusions, and aspiration of ascites. Neurogenic Tumors Neurogenic tumors, which include ganglioneuroma, ganglioneuroblastoma, and neuroblastoma, are the second most common mediastinal neoplasm in children; the vast majority of these are located in the posterior mediastinum. From a thoracic Figure 96-2. Thoracoscopic view of a neuroblastoma arising from a stellate ganglion in the apex of the right hemithorax in a patient who presented with a Horner syndrome. presentation perspective, these children may present with respiratory distress or a Horner syndrome (ipsilateral ptosis, myosis, anhydrosis, and heterochromia). Figure 96–2 demonstrates a thoracoscopic view of a neuroblastoma arising from a stellate ganglion in the right chest in a patient who presented with Horner syndrome; figure 96–3 illustrates this same right-sided thoracic tumor on a coronal view of a magnetic resonance image. These patients may also present with neurologic symptoms related to a dumbbell-shaped tumor involving the chest and spinal canal simultaneously; the latter may have cauda equina syndrome or paraplegia. 23 Figure 96-3. Magnetic resonance image (coronal) of a patient with clinical features of a Horner syndrome and a right-sided thoracic tumor in the apex of the chest, likely arising from the ipsilateral stellate ganglion.
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Chapter 96

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