1. Introduction

    Masses in the mediastinum can compress vital structures and cause changes in cardiac output, obstruction to air flow, atelectasis, or central nervous system changes. Masses can include benign or cancerous tumors, thymomas, substernal thyroid masses, vascular aneurysms, lymphomas, and neuromas. Surgical procedures for diagnosis or treatment of these masses may include thoracotomy, thoracoscopy, and mediastinoscopy.

    Tumors within the anterior mediastinum can cause compression of the trachea or bronchi, increasing resistance to air flow. Changes in airway dynamics with supine positioning, induction of anesthesia, and positive-pressure ventilation can cause collapse of the airway with total obstruction to flow. Manipulation of tissue intraoperatively, edema, and bleeding into masses can increase their size and effects on airways or vasculature. As a result, total airway obstruction can occur at any phase of anesthesia, including during positioning, induction, intubation, emergence, or recovery. Positive pressure ventilation may be impossible even with a properly placed ETT if the mass encroaches on the airway distal to the ETT. Localization of the mass by computed tomography (CT) or bronchoscopy may facilitate placement of the ETT distal to the mass. Maintenance of spontaneous ventilation retains normal airway-distending pressure gradients and can maintain airway patency when positive pressure will not. Maintenance of spontaneous ventilation is the goal when managing these patients.

2. Clinical manifestations