578931 research-article2015

SCVXXX10.1177/1089253215578931Seminars in Cardiothoracic and Vascular AnesthesiaPearson and Tan

Reviews

Pediatric Anterior Mediastinal Mass: A Review Article

Seminars in Cardiothoracic and Vascular Anesthesia 1­–7 © The Author(s) 2015 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1089253215578931 scv.sagepub.com

Jared Kevin Pearson, MD1 and Gee Mei Tan, MD2

Abstract One of the more challenging cases facing a pediatric anesthesiologist is the management of patients presenting with an anterior mediastinal mass (AMM). Patients with an AMM may have severe cardiopulmonary compromise that can be exacerbated when undergoing general anesthesia. Several case reports have documented cardiopulmonary collapse during induction or maintenance of general anesthesia and even for procedures done without anesthesia. Despite increased understanding and management of these patients, perioperative complications, defined as anything from transient decreases in blood pressure correcting with fluids or mild airway obstruction requiring no intervention, to complete cardiopulmonary collapse, are still estimated to occur during 9% to 20% of anesthetic procedures. The purpose of this review article is to provide foundational knowledge of the anatomy and physiology of a patient with an AMM, with particular emphasis on the pediatric patient. It will assist in recognizing presenting signs and symptoms and discuss the appropriate preoperative testing, which together can help assess perioperative risk and determine the appropriate anesthetic management plan for the patient’s safety and comfort. Keywords children, circulatory arrest pediatric, critical care, heart, intraoperative assessment, monitoring, pediatric intensive care, risk management, thoracic surgery

Introduction

Anatomy

One of the more challenging cases facing a pediatric anesthesiologist is the management of patients presenting with an anterior mediastinal mass (AMM). Patients with an AMM may have severe cardiopulmonary compromise that can be exacerbated when undergoing general anesthesia. Several case reports have documented cardiopulmonary collapse during induction or maintenance of general anesthesia and even for procedures done without anesthesia.1-3 Despite increased understanding and management of these patients, perioperative complications, defined as anything from transient decreases in blood pressure correcting with fluids or mild airway obstruction requiring no intervention, to complete cardiopulmonary collapse, are still estimated to occur during 9% to 20% of anesthetic prcedures.4-6 The purpose of this review article is to provide foundational knowledge of the anatomy and physiology of a patient with an AMM, with particular emphasis on the pediatric patient. It will assist in recognizing presenting signs and symptoms and discuss the appropriate preoperative testing, which together can help assess perioperative risk and determine the appropriate anesthetic management plan for the patient’s safety and comfort.

The mediastinum can be divided into 3 compartments: anterior (superior and inferior segments), middle, and posterior. Although these anatomical compartments can be easily delineated on chest radiograph (Figure 1), it is important to note that there are no anatomical or fascial planes that separate them. Masses originating in one compartment may frequently cross over to another. The location of the mass is important because masses that occupy the anterior mediastinum are far more commonly associated with increased perioperative risks, and in the pediatric population, most masses are found here.4,7,8 In a retrospective study of perioperative complications in 117 pediatric patients, it was found that all who experienced perioperative complications (9.5% of the total) had masses in the anterior mediastinum, whereas patients with masses isolated to the middle or posterior compartments experienced 1

Utah Valley Regional Medical Center, Provo, UT, USA Children’s Hospital Colorado, Aurora, CO, USA

2

Corresponding Author: Jared Kevin Pearson, MD, Utah Valley Regional Medical Center, 1034 N 500 W, Provo, UT 84604, USA. Email: [email protected]

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Seminars in Cardiothoracic and Vascular Anesthesia 

Figure 1.  Chest radiograph indicating the anterior, middle, and posterior mediastinal compartments. Table 1.  Diagnosis by Percentage of Anterior Mediastinal Mass Comparing Children With Adults.

Lymphomas Germ cell tumors Thymomas Others

Children (%)

Adults (%)

45 24 16 15

23 14 47 16

no complications.4 These findings are similar to those of an earlier retrospective study, in which, of the 15% of patients who experienced perioperative complications, 85% had an AMM.9 Given the variety of tissue types from which a mass may arise, attempts have been made to determine anesthetic risk depending on tissue diagnosis. Although it appears that there is no correlation between tissue diagnosis and anesthetic risk in adults,5 T-cell lymphoblastic leukemia and nonHodgkins lymphoma have both been reported to increase the risk of perioperative complications in children.4,10 However, different pathological masses have a predilection for different compartments,11 and both these tissue types arise from the anterior mediastinum. Thus, the apparent association may be explained by the fact that lymphomas are more frequently the cause of AMM in children (Table 1).

Physiology A patient’s anesthetic risk can be best appreciated by understanding the physiological perturbations that can

occur in patients with an AMM. Patients with an AMM can experience cardiopulmonary symptoms as a result of airway, cardiac, or major vessel compression. Hemodynamic compromise can occur when the mass compresses the right cardiac chambers, superior vena cava (SVC), pulmonary arteries, or pulmonary veins, resulting in decreased left-ventricular preload and cardiac output. Compression of the pulmonary arteries not only decreases pulmonary perfusion, resulting in hypoxemia and hypoventilation, but can also lead to right-ventricular failure. Pulmonary vein compression can lead to decreased cardiac output, hypoxemia, and pulmonary edema. Respiratory compromise can occur from tracheal or bronchial compression manifested by symptoms of shortness of breath, cough, or stridor.12 Cardiopulmonary effects of AMM compression can worsen V/Q mismatch, depending on patient position and depth of anesthesia. When patients are supine, gravitational effects on the chest wall and mediastinal mass together with a cephalad movement of the diaphragm increases intrathoracic pressure and may worsen external compression of the major vessels and airways. These effects are magnified under general anesthesia with bronchial and tracheal smooth muscle relaxation, especially in pediatric patients with more collapsible airway tissue. In many patients, maintaining spontaneous ventilation can be critical because the decrease in intrathoracic pressure during inspiration may reduce the compressive effect of the AMM and help maintain airway patency. In contrast, positive pressure ventilation increases intrathoracic pressure, which may cause complete collapse of the trachea, bronchi, or major vessels. Neuromuscular blockade may also enhance collapse of these structures because of loss of tone of the supporting musculature of the chest wall, neck, and supraglottic airway. If the AMM sits at or below the level of the carina, inability to ventilate or oxygenate may persist despite endotracheal intubation.

Signs and Symptoms Predictive of Perioperative Complications Patients with AMM present with a myriad cardiopulmonary and constitutional signs and symptoms (Table 2) that are often dependent on mass size, position, and the rapidity of growth. Children, compared with adults, tend to experience more signs and symptoms for several reasons. First, these masses tend to be malignant and thus grow faster and may be infiltrative. Second, children have a smaller intrathoracic volume and may not accommodate these masses as easily as adults. Finally, AMM in children tends to be more central and thus more likely to compress on their softer airway and vascular structures. The task of the anesthesia consult is to determine which signs and symptoms can predict perioperative complications. Ng et al9 reviewed 63 pediatric cases with a mediastinal mass. The complication rate was 15%,

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Pearson and Tan Table 2.  Various Signs and Symptoms Associated With an Anterior Mediastinal Mass Organized by Airway or Cardiac Compression and Nonspecific Constitutional Symptoms. Airway Compression

Cardiac Compression

Constitutional Symptoms

Cough Chest fullness Dyspnea Hoarseness Stridor Orthopnea

Syncope Tachycardia Jugular venous distension SVC syndrome Cyanosis

Fevers Night sweats Weight loss      

Abbreviation: SVC, superior vena cava.

including problems with ventilation, intubation, and cardiovascular collapse, and resulted in 2 deaths and 1 tracheostomy. They reported that patients with evidence of tracheal or vascular compression, infection, and at least 3 respiratory symptoms are at increased risk under general anesthesia. All patients with complications had at least 3 respiratory signs and symptoms consisting of cough, shortness of breath, orthopnea, pleural effusion, accessory muscle use, stridor, or history of respiratory arrest. In contrast, 83% of the cohort with no perioperative complications had

Pediatric Anterior Mediastinal Mass: A Review Article.

One of the more challenging cases facing a pediatric anesthesiologist is the management of patients presenting with an anterior mediastinal mass (AMM)...
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