06 May, 2012

Chylothorax



The Management of Chylothorax 


Is controversial because no prospective studies exist to guide therapy [22]. Furthermore, variations on management approaches, such as thoracic duct ligation by thoracotomy or thoracoscopy and selection of different pleurodesis (ie, sclerosing) agents, may offer similar outcomes and allow clinicians to individualize therapy. Three principles, however, should be applied. Most patients benefit from a staged care plan that proceeds from initial conservative pleural space drainage with nutritional support to surgical intervention. • Patients with large volume drainage (>1L per day) of chylothoraces through chest tubes will most likely require early, aggressive surgical approaches. Overly prolonged drainage of a chylothorax should be avoided to prevent patients from becoming immunosuppressed and malnourished, which limits their tolerance of definitive surgical therapy.
Nontraumatic chylothorax — Patients with underlying lymphoma or metastatic cancer frequently respond to therapy directed at the primary tumor or metastatic sites. Older reports, for example, showed that 68 percent of patients with lymphoma and 50 percent with metastatic carcinoma had resolution of the chylothorax after radiation therapy. Failure of the chylothorax to resolve after radiation or chemotherapy generally requires instillation of a pleural sclerosing agent (such as talc) through a chest tube or a thoracoscope .
Malignant chylothorax does not usually benefit from surgical ligation of the thoracic duct [28]. However, some patients may be suitable candidates for pleuroperitoneal [29] or pleurovenous shunting . Two types of pleuroperitoneal shunts are available, an active version that requires frequent activation of a manual pump (Denver pleuroperitoneal shunt) or a passive version (LeVeen pleuroperitoneal shunt) . These procedures recycle the nutritionally important constituents of chyle and avoid surgery.A retrospective case control study of 10 patients with malignant chylothorax found a favorable response to outpatient use of an indwelling pleural catheter, compared to alternative strategies, such as repeated thoracenteses, a pleuroperitoneal shunt, and talc pleurodesis (one patient) .
Patients with symptomatic, idiopathic chylothoraces and a negative evaluation for malignancy can undergo "conservative" therapy with chest tube drainage and a regimen aimed at limiting the flow of chyle, consisting of a period of low fat, limited oral intake with or without parenteral nutrition. Some clinicians supplement the oral diet with medium chain triglycerides (MCT), which directly enter the portal system rather than the intestinal lymphatics . The MCT diet, however, is variably successful because thoracic duct flow is not lowered to the same degree as during a fasting state with total parenteral nutrition.Pleural drainage and diet therapy leads to resolution of an idiopathic chylothorax in 80 percent of cases, usually within 2 to 3 weeks, especially if the chylothorax was induced by unrecognized minor trauma . Prolonged chest tube placement presents a negligible risk for pleural space infection because of the bacteriostatic properties of chyle .More aggressive therapy is warranted if a symptomatic idiopathic chylothorax persists. The timing of therapy depends on the size of the effusion, the rate of pleural fluid drainage, and the severity of associated symptoms. Treatment options include pleurodesis [25,26,35], pleurectomy, oversewing of a thoracic duct disruption, oversewing of leaking collaterals, and ligation of the thoracic duct at the hiatus. Some reports indicate that surgical closure of a leak in the thoracic duct can be achieved through thoracoscopy either by ligature or by application of fibrin glue .
Talc pleurodesis can also be performed by thoracoscopy to resolve a chylothorax . Identification of the point of leakage during an open or thoracoscopic procedure is aided by giving the patient a lipophilic green dye or a high fatty fluid, such as cream, orally before surgery. Patients with unusual causes of chylothorax, such as lymphangioleiomyomatosis, lupus, or sarcoidosis, may respond to medical therapy directed at their underlying disease. In some instances, these patients may benefit from chemical or surgical pleurodesis. Nonsurgical traumatic chylothorax — A symptomatic chylothorax induced by nonsurgical trauma is managed with chest tube placement, maintenance of fluid and electrolyte balance, and bowel rest with parenteral nutrition to minimize the flow of thoracic duct chyle.Chest tube drainage of the pleural space is successful in allowing the rent in the thoracic duct to close spontaneously in 50 percent of patients. If chyle continues to drain from the chest tube, one of the available surgical approaches should be considered to stop the intrapleural accumulation of chyle. No strict guidelines exist for determining the timing of these interventions, although two issues play an important role in this decision:
• The use of thoracic duct drainage of lymphocytes to immunosuppress patients in preparation for organ transplantation has shown that 14 days of chylous drainage results in a clinically important degree of immunosuppression. Thus, patients with traumatic chylothoraces should undergo conservative therapy with pleural fluid drainage for no longer than 14 days to minimize the risk of infection, protein loss and malnutrition.
• Earlier surgical intervention within 7 days is required if the daily drainage of pleural fluid exceeds 1 liter, or if the drainage of chyle results in weight loss and progressive hypoproteinemia despite aggressive nutritional therapy .
Selection of a surgical approach depends upon available surgical skills and experience. Most centers ligate the thoracic duct above the hiatus and attempt to repair lymphatic structures at sites of disruption. Thoracic duct ligation alone without repair at the site of disruption may fail to control a chylothorax if a distal disruption is fed by collateral lymphatics. The preferred approach is to repair the site of lymphatic disruption and avoid ligation of the thoracic duct, when possible, to preserve chyle flow through the thoracic duct [12]. Minimally invasive thoracoscopic techniques are increasingly being used for thoracic duct ligation [40,43,44]. Insufflation of talc through a thoracoscope has been reported to control chylothoraces from lymphoma by creating a pleural symphysis .
Postoperative (surgical) chylothorax — Postoperative chylothorax represents a grave complication with a mortality rate that may approach 50 percent [11]. The chylous nature of the pleural fluid chest tube drainage may not be recognized for as long as 15 days after surgery and can result in nutritional depletio. Management includes chest tube drainage and parenteral nutrition with the patient fasting or orally supplemented with MCT. This regimen is continued for a variable period before surgical intervention (eg, thoracoscopic thoracic duct ligation or pleurodesis) is undertaken . The duration of conservative therapy is influenced by a number of factors:
• Patients draining more than 1 L/day may benefit from surgical interventions within 5 to 7 days . Patients with less than 500 mL of chest tube drainage in the first 24 hours after cessation of oral intake and initiation of total parenteral nutrition tend to improve with conservative management .
• Patients with chylothoraces after resection of a malignancy, such as esophageal cancer, are less likely to respond to conservative therapy because they are often leaking chyle from lymphatic collaterals that seldom heal spontaneously. Furthermore, these patients are often immunocompromised and nutritionally depleted and may benefit from earlier surgical intervention and more rapid resolution of chyle drainage within one week of onset .
• Patients with a chylothorax in a pneumonectomy space are observed without chest tube drainage unless the mediastinum shifts to the midline. In this setting, a chest tube is placed to prevent a life-threatening tension chylothorax [16]. This should be followed by direct open surgical or thoracoscopic control of the lymphatic leak .
• Chylothorax after lung transplantation for lymphangiomyomatosis has been successfully treated with a pleurovenous shunt when conventional therapy failed .
• Young, low risk patients may undergo earlier surgical repair to decrease hospital stay .
• Inhaled nitric oxide has been employed in infants when pulmonary and central venous hypertension are thought to be contributing to the persistence of chylothoraces by impairing thoracic duct drainage following surgery .

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