Preoperative Evaluation and Questions: Indication for surgery? Bronchogenic CA? Concern for Airway compression? Mediastinal masses may compress upper airway after induction. If patient has large mass may need careful plan for induction and intubation.
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Open in new tab Thymic tumours are associated with myasthenia gravis that causes weakness and fatigability of voluntary muscles. Clinical manifestations range from isolated ocular symptoms to respiratory muscle involvement. Patients with myasthenia gravis are sensitive to non-depolarizing muscle relaxants and have a variable response to depolarizing agents.
Eaton—Lambert syndrome myasthenic syndrome is proximal myopathy associated with small cell carcinoma. Reduction in acetylcholine released from presynaptic motor nerve terminals in these patients causes increased sensitivity to all neuromuscular blocking drugs. In contrast to myasthenia gravis, the muscle weakness improves with exercise and is not reversed by acetyl cholinesterase inhibitor therapy.
Investigations In addition to routine haematology, biochemistry, and ECG, preoperative investigations should include chest X-ray, and CT scan aimed at evaluating the location of the tumour, its relation to adjoining structures, and the degree of tracheal compression.
Pulmonary function tests are useful in detecting the severity of pre-existing lung disease and effects of mediastinal mass. Flow—volume curves should be obtained in the upright and supine position to evaluate functional impairment and ascertain the presence of obstruction.
Both inspiratory and expiratory flows are usually reduced in the presence of an intrathoracic mass. A disproportionate decrease in maximal expiratory flow should raise suspicion of tracheomalacia.
Additional investigations e. Anaesthetic management Large bore intravenous cannulae should be inserted and cross-matched blood should be available because of the potential risk of haemorrhage.
If the patient is asymptomatic, preoxygenation followed by intravenous induction of anaesthesia can be performed. In the presence of respiratory obstruction, an awake intubation under local anaesthetic is the technique of choice. This allows the entire anaesthetic and surgical team to view the exact level of obstruction and the endotracheal tube is passed distal to obstruction. In case of a more distal obstruction carinal level , a rigid bronchoscope should be available for low-frequency jet ventilation.
Alternatively, an inhalation induction may be used, followed by intubation of the trachea under deep anaesthesia. Surgical access is improved by resting the shoulders on a sandbag and the head on a head ring. An intravenous anaesthetic agent, inhalational anaesthetic agent, or both, together with a neuromuscular blocking agent and a bolus or continuous infusion of a short-acting opioid will allow an adequate level of anaesthesia and rapid postoperative recovery.
Ventilation of both lungs through a single-lumen endotracheal tube is usually adequate. A reinforced tube is preferred to minimize the risk of the tube kinking during surgery. With a long-standing mass, fibreoptic endoscopy should be performed prior to extubation to rule out tracheomalacia. Ideally, muscle relaxants should be avoided in patients with clinical features suggestive of myaesthenic syndrome.
If used, doses should be carefully titrated to response as measured by neuromuscular monitoring. Patients should only be extubated after full recovery of reflexes and neuromuscular function; a short period of postoperative ventilation may be required.
Local anaesthetic infiltration of the wound, superficial cervical plexus and intercostal nerve blocks aid postoperative analgesia. Regular paracetamol and NSAIDs if not contraindicated could be prescribed as part of multimodal analgesia.
Postoperatively, a chest X-ray should be taken in all patients in the recovery room to exclude pneumothorax. Subsequently, patients can be cared for on the ward; they should be observed specifically for dyspnoea and stridor, which may be caused by injury to the recurrent laryngeal nerve or a paratracheal haematoma. Monitoring Invasive arterial blood pressure monitoring is preferred for the early detection of reflex arrhythmias and compression of major vessels with mediastinoscope.
This should preferably be sited in the right arm for detection of brachiocephalic compression, which results in reduction in blood flow to the right carotid artery and may cause ischaemia in the presence of inadequate collateral circulation. Alternatively, the pulse oximeter probe should be placed on the right hand. Neuromuscular monitoring is mandatory in patients with myasthenia gravis and Eaton—Lambert syndrome. The ventilator pressure gauge should also be observed to note any acute increase in airway pressure, which indicates tracheal or bronchial compression by the mediastinoscope.
The use of pressure-controlled ventilation helps in the early detection of a rise in airway pressure.
Mediastinoscopy: vascular compression
Personnel Mediastinoscopy is a surgical procedure that is performed in the operating room. The procedure also requires general anesthesia and thus requires an anesthesiologist and operating room support staff. Mediastinoscopy can be performed under local or general anesthesia. General anesthesia is the technique of choice at most institutions if the patient has no preoperative signs or symptoms of airway obstruction. An intravenous line must be in place before proceeding to the operating room. The general anesthetic technique can involve inhalational or intravenous agents, or most commonly, a combination of the two.