Urgent considerations
See Differentials for more details
Superior vena cava syndrome
Superior vena cava (SVC) syndrome occurs when the SVC is occluded or compressed by a mediastinal mass. Malignant tumours are commonly associated with SVC syndrome. In most cases, SVC syndrome is not a medical emergency unless neurological symptoms are present.[28] A biopsy should be obtained prior to the initiation of therapy. Biopsies can often be obtained from percutaneous biopsy, sampling of more accessible synchronous lesions, or via mediastinoscopy. Treatment is directed at the underlying disease process, with consideration of endovascular SVC stent placement for acute severe symptoms until the primary tumour has sufficiently shrunk to relieve compressive symptoms.
Tracheal obstruction
Tracheal obstruction may occur from primary endoluminal tumour growth or from extrinsic compression. The majority of tracheal tumours are malignant, with squamous cell carcinoma and adenoid cystic carcinoma being the most common histologies.[23] Extrinsic tracheal compression can occur from tumours of surrounding tissues such as thyroid, oesophagus, lymph nodes, and lung.[29][30] These malignancies may also directly invade the trachea through local extension.
Symptoms of progressive or dynamic tracheal obstruction include dyspnoea, cough, haemoptysis, and stridor. Acute respiratory distress may not be present until the trachea is almost completely occluded, and may prove lethal without immediate intervention. Standard chest radiography is insensitive for the detection of tracheal tumours.[31] Computed tomography (CT) scan is the imaging modality of choice, including both inspiratory and expiratory imaging. Bronchoscopy, whether flexible or rigid, is the best way to visualise the degree of tracheal obstruction, with the ability to concomitantly debulk the tumour through rigid bronchoscopy. Rapid recognition and surgical intervention is required for near complete tracheal obstruction.[32]
Bronchial obstruction
Bronchial obstruction could occur from intrinsic or extrinsic tumour compression. Intraluminal bronchial tumours are often malignant, with small cell carcinoma and squamous cell carcinoma being the most common histologies. Extrinsic bronchial compression can occur from tumours of surrounding tissues, such as lymph nodes and lung, or occasionally from an aneurysm. Symptoms include dyspnoea, cough, haemoptysis, and wheezing.
Standard chest radiograph may identify a mass lesion with associated unilateral lung collapse. CT scan is the imaging modality of choice.[31] Bronchial obstruction may be addressed surgically or with radiotherapy after the underlying tumour is diagnosed.[33]
Thoracic aortic aneurysm rupture
The natural history of thoracic aortic aneurysms involves gradual expansion and eventual rupture if untreated.[8][9] When a thoracic aortic aneurysm ruptures, sudden death may ensue. Patients may present with sudden-onset severe chest pain that may have a tearing character and radiate to the back. Syncope, light-headedness, and a feeling of impending doom may be present. Presenting signs include tachycardia, hypotension, and shock.
Chest x-ray may show widened mediastinum.[34] CT angiogram of the chest is the test of choice to diagnose a suspected rupture.[35] Emergent vascular or cardiothoracic surgery referral should be made if the diagnosis is suspected on clinical grounds, and critical care maintained until surgery.[36]
Aortic dissection
Aortic dissection occurs when an intimal tear causes blood to enter into the intima-media space of the aorta, resulting in a false lumen. The false lumen may extend in an antegrade (towards the descending aorta) or retrograde (towards the aortic valve) direction. The most common causes of aortic dissection are hypertension, congenital bicuspid aortic valve, and collagen vascular disorder.[37][38]
Frequency by location of dissection has been reported as: ascending aorta 65%, descending aorta 20%, aortic arch 10%, and abdominal aorta 5%.[39] Signs and symptoms depend on the location of dissection, vascular branch involvement, and presence of rupture. Pain is almost universal and often described as tearing or shearing with radiation to the back or neck.[40][41] Regional ischaemia may occur from branch vessel involvement.
Chest x-ray may show widened mediastinum and/or displacement of aortic intimal calcification, but a normal chest x-ray does not exclude the diagnosis. ECG is useful to exclude concomitant myocardial infarction. Trans-oesophageal echocardiography, magnetic resonance imaging (MRI), and contrast-enhanced CT scan are the diagnostic modalities of choice.[42] In unstable patients who cannot be taken to the scanner, trans-oesophageal echocardiography can rapidly make the diagnosis. In more stable patients, a CT scan or MRI can make the diagnosis as well as give more information regarding extent of dissection and arch involvement, which is critical in operative planning.[43]
Once an aortic dissection is suspected, critical care and cardiothoracic surgery services should be activated.[36]
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