Chylothorax: A review of current management strategies

The most common causes of chylothorax are neoplasmparticularly lymphoma-and trauma. The usual presenting symptom is dyspnea resulting from the accumulation of pleural fluid. The diagnosis of chylothorax is established by measuring triglyceride levels in the pleural fluid; a triglyceride level of greater than 110 mg/dL supports the diagnosis. The initial approach to management involves chest tube drainage of the pleural space. The administration of medium-chain triglycerides as a source of fat is often useful. If drainage remains unchanged, parenteral alimentation should be started. Surgical intervention is indicated if conservative management is not successful or if nutritional deterioration is imminent. If chylothorax persists after ligation of the thoracic duct, options may include percutaneous embolization, pleuroperitoneal shunt, and pleurodesis. (J Respir Dis. 2008;29(8):325-333) ABSTRACT: The most common causes of chylothorax are neoplasm—particularly lymphoma—and The most common causes of chylothorax are neoplasm—particularly lymphoma—and trauma. The usual presenting symptom is dyspnea resulting from the accumulation of pleural fluid. The diagnosis of chylothorax is established by measuring triglyceride levels in the pleural fluid; a triglyceride level of greater than 110 mg/dL supports the diagnosis. The initial approach to management involves chest tube drainage of the pleural space. The administration of medium-chain triglycerides as a source of fat is often useful. If drainage remains unchanged, parenteral alimentation should be started. Surgical intervention is indicated if conservative management is not successful or if nutritional deterioration is imminent. If chylothorax persists after ligation of the thoracic duct, options may include percutaneous embolization, pleuroperitoneal shunt, and pleurodesis. (J Respir Dis. 2008;29(8):325-333) Chyle in the pleural space was first described by Bartolet in 1633, and since that time, numerous causes have been well described.1 The pleural fluid in chylothorax consists of chylomicrons and very-low-density lipoproteins. It results from an anatomical disruption of the thoracic duct or a major lymphatic contributory or both. In 1948, Lampson2 reported the first successful treatment of chylothorax by supradiaphragmatic ligation of the thoracic duct. Although chylothorax accounts for a small proportion of pleural effusions, prompt recognition is needed to avoid malnutrition and to prevent immunodeficiency. In this article, we will review the various causes of chylothorax, the diagnostic workup, and management options. ANATOMY Chyle passes from the intestinal lymphatics to the cisterna chyli and through the thoracic duct to empty into the venous system. The thoracic duct begins at the cisterna chyli near the T12 vertebra and ascends through the aortic hiatus of the diaphragm on the anterior surface of the vertebral body between the aorta and azygos vein into the posterior mediastinum. At the level of the T5 vertebra, the duct crosses to the left of the vertebral column and ascends behind the aortic arch to the left of the subclavian artery adjacent to the mediastinal pleura. At the level of the transverse process of the C7 vertebra, the thoracic duct turns laterally and runs anterior to the vertebral and thyrocervical arteries and the sympathetic trunk. Passing behind the carotid sheath, the duct descends anterior to the origin of the left subclavian artery and terminates near the junction of the internal jugular and subclavian veins. A bicuspid valve at the lymphovenous junction prevents the reflux of blood into the duct. The duct has numerous valves throughout its length. However, in up to 50% of persons, the route of the thoracic duct is anomalous and unpredictable, making it more susceptible to damage during surgical procedures. 3 This duct carries lymph from the entire body except from the right side of the head, neck, and chest; both lungs; and the right upper extremity. The lymph from the right side of the neck