Anesthesia for Patients with Mediastinal Masses

Abstract

Patients with mediastinal masses can develop major airway and cardiovascular compression under general anesthesia, which could be fatal in nature. The key to management of these patients lies in early recognition of high-risk features and formulation of an anesthetic plan appropriate for the severity of symptoms. High-risk features include respiratory symptoms that are worsened in the supine position, such as orthopnea and increased cough, superior vena cava syndrome, pericardial effusion, and evidence of airway or cardiovascular compression on CT imaging. Knowledge of the anatomical location of the mass, as well as its relationship to vital cardiorespiratory structures, careful preoperative assessment, meticulous planning in conjunction with the surgeon, and preparation for possible perioperative complications are paramount in successful management of these patients. Diagnostic procedures should be performed under local anesthesia whenever feasible. If general anesthesia is required, induction should proceed in a stepwise fashion with confirmation of adequate ventilation and circulation before proceeding to the next step. Strategies for airway management include awake fiber-optic assessment of dynamic obstruction, intubation distal to airway compression, maintenance of spontaneous ventilation, and avoidance of muscle relaxation. Management of acute airway obstruction or cardiovascular collapse may include advancing tube beyond obstruction, repositioning patient, resumption of previously tolerated state, rigid bronchoscopy, and initiation of cardiopulmonary bypass (CPB) or extracorporeal membrane oxygenation (ECMO). Preinduction CPB and ECMO should be considered in extremely high-risk patients as rescue CPB may not be established rapidly enough in acute airway or cardiovascular collapse to prevent anoxic consequences.

Clinical Case Discussion

A 24-year-old female presented with a 1-week history of progression of dry cough and increased facial and neck swelling (especially in the morning on awakening). She also notes increasing shortness of breath, especially when lying flat. Chest X-ray (Fig. 14.4 a, b) demonstrates a large anterior mediastinal mass as well as a right pleural effusion. CT scan demonstrates a 6.3 x 8.7 x 8.0 cm soft tissues mediastinal mass that is encasing the superior vena cava, both brachiocephalic veins, and the right pulmonary artery (Fig. 14.5 a–d). The trachea and mainstem bronchi are compressed. Percutaneous CT-guided biopsy was nondiagnostic (Fig. 14.6 a–c).

Fig. 14.4

Chest X-ray of a 24-year-old female patient with a large anterior mediastinal mass presenting for biopsy of the mass under GA. (a) CXR shows presence of a right-sided pleural effusion. (b) Repeat CXR after pleural effusion was drained. Recent percutaneous CT-guided biopsies were nondiagnostic. She presented with symptoms of SVC obstruction. The trachea appears midline and patent on CXR

Fig. 14.5

(a–d) CT scan (sagittal views) of the same patient shows a large anterior mediastinal mass measuring 6.3 × 8.7 × 8.0 cm. There is encasement and compression of the SVC, both brachiocephalic veins, and the right pulmonary artery

Fig. 14.6

(a–c) CT scan (coronal views) of the same patient shows tracheal and bilateral mainstem bronchi compression by anterior mediastinal mass to almost a slit. The patient was intubated awake beyond the area of maximal tracheal compression

Question 1

Anterior mediastinoscopy is planned to obtain tissue biopsy samples. What are your options for induction of anesthesia?

Answer

This patient has several high-risk features (increased shortness of breath and cough when supine as well as SVC syndrome). Options include local anesthesia (if feasible), awake fiber-optic intubation, and inhalational induction with avoidance of muscle relaxation. Discussion with the surgical team should also include the possibility of preinduction CPB or ECMO with the encasement of SVC. If local anesthesia is not feasible, awake fiber-optic assessment of the airway, followed by passage of endotracheal tube distal to obstruction, may be the safest technique. This also allows for assessment of any dynamic airway obstruction during spontaneous ventilation, association with any positional changes, and identification of the least obstructed bronchus.

Question 2

You successfully performed an awake fiber-optic intubation of this patient. There is moderate mid-tracheal compression and mild compression of bilateral bronchi on examination. A long endotracheal tube (ETT) is placed beyond the area of tracheal compression. Soon after administration of a muscle relaxant, ventilation becomes more difficult, and patient begins to desaturate. BP is 60/42. What do you suspect?

Answer

The differential diagnosis includes acute airway obstruction as well as potential compression of major cardiovascular structures.

Increase in airway pressure may suggest obstruction distal to the ETT. A quick check with the bronchoscopy may help verify this, and the ETT can be advanced beyond the obstruction (endobronchial intubation may be required).

SVC compression will lead to decreased venous return and subsequent reduction in cardiac output. The cessation of spontaneous ventilation will also augment the decrease in venous return. Profound hypotension will lead to insufficient pulmonary perfusion and hypoxemia.

Cyanosis and hypoxemia can also occur with RVOT obstruction and should be considered in this patient.

Question 3

The patient begins to desaturate despite attempts at bronchoscopic adjustment of the endotracheal tube and adjustment of patient position from supine to upright. The surgeons are scrubbing. What should you do?

Answer

Immediately alert the surgeon. The plan may be to proceed immediately to sternotomy to lift the mediastinal mass to relieve its compressive effects. CPB and ECMO may be considered but may not be achieved quickly enough if preinduction cannulation of vessels was not performed.

The surgeons quickly perform a sternotomy, and upon lifting the mass off the trachea and right pulmonary artery, the airway pressure, saturation, and blood pressure improved dramatically.