Anterior Mediastinal Mass (AMM)

Preoperative imaging - Contrast-enhanced chest CT with multiplanar reconstruction is the study that matters: it shows mass size, degree of tracheal compression, involvement of the great vessels, and the collateral circulation when the SVC is compressed or invaded.

Flow-volume loops - PFTs give a dynamic read on the obstruction. An inspiratory plateau means variable extrathoracic obstruction, an expiratory plateau with normal inspiratory flow means intrathoracic, and flattening of both means a fixed lesion. Routine upright-and-supine spirometry has not predicted complications any better than symptoms plus chest CT, so don't order it reflexively.

Look for compression symptoms - Cough, chest pain, dyspnea, hoarseness, and dysphagia are the localizing complaints. Facial and periorbital edema, proptosis, facial plethora, and upper-extremity swelling mean SVC syndrome. Hoarseness earns a laryngoscopic look at the cords.

Awake intubation when the airway is compromised - If the preoperative workup shows major airway compromise, intubate awake with minimal sedation and keep spontaneous ventilation. A rigid bronchoscope and a bronchoscopist who can use it must be in the room before anyone touches the airway; the rigid scope bypasses the obstruction and gives a ventilation path if the airway collapses completely.

Tube choice follows the incision - Sternotomy takes a single-lumen ETT, and an armored single-lumen tube resists compression by the mass. Thoracotomy needs lung isolation: secure the airway with a single-lumen tube, then add a bronchial blocker, which can be pulled while leaving the ETT in place if postoperative ventilation is needed. A distal extrathoracic lesion compressing a bronchus favors a double-lumen tube for its extra length past the obstruction and independent lung ventilation.

Know about any stent - A tracheal or bronchial stent can be dislodged while placing the ETT.

Access and monitoring - Two large-bore IVs plus an arterial line for a large mass. If the SVC is involved, place a large catheter in the femoral vein or another lower-extremity vessel so volume doesn't have to cross the obstruction. Add central venous pressure monitoring where major hemorrhage is plausible; these tumors are fed by internal mammary, bronchial, intercostal, pulmonary, and even coronary branches.

Thymoma means think myasthenia - 30% to 50% of thymoma patients have myasthenia gravis (MG). Continue anticholinesterase and steroid therapy through the day of surgery. Nondepolarizing agents are unpredictable in MG, so use a quantitative neuromuscular monitor both to dose and to prove full reversal; rocuronium reversed with sugammadex has allowed successful extubation. Succinylcholine is acceptable for intubation when the mass is not compressing the airway.

Mediastinoscopy hazards - Major hemorrhage is the worst complication and may force an emergent thoracotomy. Also watch for airway obstruction, innominate artery compression, pneumothorax, recurrent laryngeal and phrenic nerve injury, esophageal injury, chylothorax, and air embolism. Morbidity runs 2% to 8%.

Extubation is not the finish line - Tracheomalacia after removal of a large mass can force continued intubation. More than 50% tracheal compression on the preoperative CT plus a mixed obstructive-restrictive PFT pattern predicts a high likelihood of reintubation. Keep a videolaryngoscope, supraglottic airways, and a flexible fiberoptic bronchoscope at the bedside.

An anterior mediastinal mass sits in the compartment that holds the thymus, fat, and lymph nodes, so the usual culprits are thymoma, lymphoma, thyroid goiter, and germ cell tumors. About 59% of anterior compartment masses are malignant, and 60% of patients are symptomatic at presentation, cough being the most common complaint.

The perioperative problem is mechanical. The mass compresses the lower third of the trachea and the main bronchi, and it compresses the superior vena cava, pulmonary vessels, and adjacent organs. That compression can declare itself when the patient is placed supine, at induction, intraoperatively, at extubation, or in the postoperative period. Large masses produce severe hypoxemia from total left main bronchus obstruction combined with pulmonary artery compression, and severe airway obstruction before or after surgery can generate noncardiogenic pulmonary edema.