SummaryA patient with a large anterior mediastinal mass with minimal respiratory symptoms presented for a diagnostic biopsy of the mass. A pre-operative thoracic computed tomographic scan demonstrated narrowing of the distal trachea, and right and left main stem bronchi. An awake intubation was done. Thiopentone and muscle relaxant were given and surgery commenced. High airway pressure developed and ventilation became difficult, although oxygenation remained satisfactory throughout. Anaesthetic implications are discussed. We recommend that patients with more than 50% obstruction of the airway at the level of the lower trachea and main bronchi have their femoral vessels cannulated in readiness for cardiopulmonary bypass. Anterior mediastinal masses are uncommon, but when they present at surgery for diagnostic or for definitive procedures, they pose serious challenges for the anaesthetist. By nature of their anatomical location, they produce three problems: compression of the heart, compression of the large vessels (principally the superior vena cava) and compression of the trachea and main bronchi. Compression of the airway can be insidious when it is intrathoracic and at the bronchial level. Thus, a patient can be asymptomatic and yet have airway compression which only manifests at induction of anaesthesia when voluntary control of the airway is lost. The anaesthetist who is unprepared will face a catastrophic situation of total obstruction of the airway leading to death of the patient.We report a case of a massive anterior mediastinal mass causing intrathoracic airway obstruction during which some anaesthetic problems arose. We also reviewed the literature and, in the light of this, present our recommendations for the management of patients with such masses. Case historyA 20-year-old Malay woman presented for a diagnostic biopsy of an anterior mediastinal mass. She had a history of a cough for one month. There was no history of dyspnoea, stridor or noisy breathing. Chest X-ray showed a massive mediastinal mass filling more than two-thirds of the chest (Figs 1 and 2) and a computed tomographic scan confirmed this finding as well as compression of both main bronchi (Figs 3 and 4).An awake intubation was done with fentanyl 100 mg, and topical anaesthesia of the oropharynx. A size 7 tracheal tube was inserted easily past the cords. Bilateral breath sounds were ascertained and the tracheal tube secured. Initial manual ventilation showed no increase in peak airway pressures. Thiopentone and atracurium were administered, anaesthesia was maintained with isoflurane and surgery commenced. It was then noticed that the peak airway pressure had increased to 50 cmH 2 O. Auscultation of the lungs revealed coarse rhonchi in both inspiration and expiration. Treatment was instituted for what was diagnosed as bronchospasm, with salbutamol given through the breathing system. There was no change in the lung sounds. Paper 961 670ᮊ 1999 Blackwell Science Ltd biopsy. A frozen section revealed a lymphoma and surgery was terminated. Mu...