Anterior Mediastinal Mass (AMM) 

 

 

Background 

 

  • The anterior mediastinal space is bordered by the sternum anteriorly, the middle mediastinum comprising the heart & great vessels posteriorly, the thoracic inlet superiorly, & the diaphragm inferiorly

  • The most frequent causes of AMMs are:

    • Lymphoma

    • Thymoma

    • Germ cell tumours

    • Metastatic lesions

    • Bronchogenic masses

    • Thyroid mass

 

 

Considerations

 

  • Risk of cardiopulmonary collapse upon induction of anesthesia:

    • Tracheobronchial obstruction, dynamic hyperinflation

    • RVOT obstruction, cardiac chamber compression 

  • Possible SVC syndrome:

    • Airway edema & potential for difficult intubation

    • ↑ intracranial pressure

    • Unreliable upper extremity IVs

  • Underlying etiology & comorbid disease:

    • Cancer 4 M’s (mass effects, metastases, medications, metabolic abnormalities)

    • Myasthenia gravis, Eaton-Lambert, thyroid, lymphoma

    • Pericardial/pleural effusions

  • Need for preoperative risk stratification based on symptoms & CT findings:

    • ​Low risk: asymptomatic or mildly symptomatic, without postural symptoms or radiographic evidence of significant compression of structures

    • Intermediate risk: mild to moderate postural symptoms, tracheal compression < 50%

    • High risk: severe postural symptoms, stridor, cyanosis, tracheal compression > 50% or tracheal compression with associated bronchial compression, pericardial effusion or SVC syndrome

  • Considerations of surgical procedures (e.g., mediastinoscopy) & feasibility of performance under local/sedation

 

 

Goals & Conflicts

 

  • Multidisciplinary optimization & planning:

    • Optimize medically prior to procedure (steroids, radiation, chemotherapy)

    • Perform procedures/biopsies under local if possible

    • Guide approach by CT findings (> 50% tracheobronchial obstruction) & positional symptoms (supine dyspnea, pre-syncope)

  • Cautious approach to general anesthesia, if it is necessary:

    • Maintain spontaneous ventilation & awake during ETT placement distal to obstruction

    • Avoid positive pressure ventilation & muscle paralysis if possible

  • Planning for intraoperative crisis:

    • Preoperative cardiopulmonary bypass

    • Invasive monitors & lines, lower extremity IVs

    • Rigid bronchoscopy & thoracic surgeon immediately available during anesthetic induction

    • Stretcher immediately available for repositioning: prone, decubitus

  • Complications: complete airway obstruction with dynamic hyperinflation, cardiac arrest from obstructive shock, hemorrhage from SVC syndrome, cardiac tamponade