Chylotharax after trauma but not after surgery has also been described after central line placement, pacemaker implantation, and embolization of a pulmonary arteriovenous malformation. Blunt trauma to the chest region is another cause of chylothorax, which has occurred after blast injuries and even simple injuries from coughing or sneezing. Mechanism
The main mechanism of chylothorax is the leaking of chyle from the thoracic duct, usually caused by a disturbance affecting the structural integrity of the thoracic duct. For example, placement of a central venous catheter can potentially disrupt drainage of lymph into the subclavian veins, followed by the thoracic duct, resulting in chylothorax. The disturbances cause the pressure in the thoracic duct to increase. Soon, collateral channels form, which eventually drain into the thorax. Trauma affecting the thoracic duct is the most common disturbing mechanism. Whether a chylothorax occurs in the left or right pleural space is a consequence of the thoracic ducts anatomic location in the body and depends on the level where the duct was injured. If the thoracic duct is injured above the fifth thoracic vertebra, then a left-sided chylothorax results. Conversely, a thoracic duct injury below that level will lead to the formation of a right-sided chylothorax. Chylothoraces most commonly occur in the right pleural space (50% of cases). Left-sided and bilateral chylothoraces are less common and occur in 33% and 17% of cases, respectively.In the case of cancer, invasion into the thoracic duct or collateral lymph channels can obstruct lymph.
A chylothorax is an abnormal accumulation of chyle, a type of lipid-rich lymph, in the space surrounding the lung. The lymphatics of the digestive system normally returns lipids absorbed from the small bowel via the thoracic duct, which ascends behind the esophagus to drain into the left brachiocephalic vein. If normal thoracic duct drainage is disrupted, either due to obstruction or rupture, chyle can leak and accumulate within the negative-pressured pleural space. In people on a normal diet, this fluid collection can sometimes be identified by its turbid, milky white appearance, since chyle contains emulsified triglycerides. Chylothorax is a rare but serious condition, as it signals leakage of the thoracic duct or one of its tributaries. There are many treatments, both surgical and conservative. About 2–3% of all fluid collections surrounding the lungs (pleural effusions) are chylothoraces. It is important to distinguish a chylothorax from a pseudochylothorax (a pleural effusion that happens to be high in cholesterol), which has a similar appearance visually but is caused by more chronic inflammatory processes and requires a different treatment. Signs and symptoms
The symptoms of a chylothorax depend its size and the underlying cause. A small chylothorax may not cause any symptoms and only be detected on a chest X-ray performed for another reason.