Answer of the case 1.2.2014 Diagnosis: Traumatic thoracic duct injury. Management: Surgical ligation Discussion: The thoracic duct can be damaged after blunt or penetrating injuries, or during a surgical or diagnostic procedure. Chylothorax from blunt trauma most commonly occurs as a result of sudden hyperextension of the spine with rupture of the duct just above the diaphragm. The injury to the duct was more likely after a heavy meal, when the duct is distended. Rarely, there is an associated fracture or dislocation of the thoracic vertebrae. The thoracic duct usually crosses the vertebral column at T5; therefore, injuries to the upper thoracic vertebrae result in left-sided chylothorax, whereas injuries to the lower vertebrae result in right-sided chylothorax. Very rarely it may be bilateral. Penetrating injuries from gunshot or stab wounds are usually overshadowed by injuries to adjacent vital structures. Chylothorax is a dreaded complication of almost any thoracic operation, particularly those in the left upper chest where the duct is vulnerable. It is estimated to complicate 0.25-0.5% of congenital cardiovascular operations, most commonly correction of patent ductus arteriousus. The increasing use of central venous catheters has been complicated by superior vena caval obstruction and chylothorax. Spontaneous rupture of the thoracic duct has also been reported. This may occur after bouts of violent coughing or vomiting. This occurs due to the shearing force of the right crus of the diaphragm against a distended thoracic duct. There is often a period of delay before a chylothorax becomes apparent after blunt trauma. A latent period of 2-15 days, but sometimes weeks or months, elapses between the injury and the onset of chylous effusion. In this case this period was 7 days. The delay is a consequence of lymph collecting in the posterior mediastinurn, usually at the right of the inferior pulmonary ligament, before it ruptures into the pleural cavity. The diagnosis rests on recognizing the aspirate as chyle. Chyle is a milky liquid that does not clot. However, in traumatic chylothorax it is frequently blood-stained at first, which may be misleading. Analysis reveals the typical composition characterstic. On microscopy the presence of fat globules, which clear with alkali and ether or stain with Sudan III, and chylomicrons is diagnostic. The optimal management of traumatic chylothorax has not been clearly defined. Any modem strategy must take into account the life-threatening nature of the disease. The mortality of traumatic chylothorax prior to 1948 approached 50%. In that year Lampson dramatically improved the management of this condition with the introduction of thoracic duct ligation. In 1954, Goorwitch reviewed the subsequent collected cases and reported a zero mortality for surgical 1igation. Such results led to a tendency towards immediate operative intervention. This policy was tempered by Maloney and Spencer who, in 1956, reported an 85% cure rate in 13 children with postoperative chylothorax managed with multiple aspirations. Together, these reports established the accepted management strategy in chylothorax of a trial of conservative treatment followed by operative intervention. The critical decision today is how long to continue the trial. The literature varies widely, recommending periods of days to months. The important principles of ideal conservative management entail adequate drainage and minimization of chyle production while maintaining nutrition. Conservative tube thoracostomy is possible, as chyle is bacteriostatic and does not usually become infected or produce a peel on the underlying lung. Adequate drainage keeps the lung expanded and this allows progressive obliteration of the pleural space around the opening of the leaking thoracic duct rather than any actual closure of the thoracic duct itself. Thus, the chyle flow usually stops after some time. Chyle formation is closely correlated with enteral fat. Most conservative regimens involve a low fat diet supplemented with medium chain triglycerides to reduce chyle production. But it must be remembered that any oral feeding will increase the output of the chyle fistula. Therefore, complete gut rest and TPN appear to provide the best conditions for fistula closure and nutritional support when available. Studies by Ramos and Bozzetti showed a significant advantage for TPN over enteral nutrition in closure rates of chylous fistulae, and better nutritional status. In general, a period of 14 days of TPN and complete gut rest is safe. There is evidence of immunological depression and risk of sepsis when this period is exceeded. This period may need to be shortened when nutritional or metabolic complication. Once a decision for surgical treatment has been reached, several options are available. These include direct ligation or oversewing of the fistula, supradiaphragmatic ligation of the duct at the hiatus, pleurodesis - chemical or surgical, the use of fibrin glue and pleuroperitoneal shunting. These methods are well described. The pleuroperitoneal shunt is useful, as the chyle is not lost through the system and the shunt is only required temporarily before the leak closes itself naturally.
Posted on: Sun, 02 Feb 2014 20:09:38 +0000