Chyle Leaks
Chyle is a fluid that primarily consists of LCT containing chylomicrons and lymphatic fluid. Chyle originates in the small bowel where the chylomicrons are formed and absorbed into the lymphatic system. In a normal condition, Chyle passes through the lymphatic system and enters the venous circulation via the thoracic duct. An obstruction or an injury to the lymphatic system may results in a Chyle leak into the pleural, pericardial, or peritoneal space. The common causes of Chyle leaks include neoplasia, infections, radiation, surgery and trauma.
Chyle Leaks
Chyle is a fluid that primarily consists of LCT containing chylomicrons and lymphatic fluid. Chyle originates in the small bowel where the chylomicrons are formed and absorbed into the lymphatic system. In a normal condition, Chyle passes through the lymphatic system and enters the venous circulation via the thoracic duct. An obstruction or an injury to the lymphatic system may results in a Chyle leak into the pleural, pericardial, or peritoneal space. The common causes of Chyle leaks include neoplasia, infections, radiation, surgery and trauma.
While Chyle leaks dont happen often they are also not rare. In the case of surgery, the overall incidence is 1-4% depending on the type of surgery (Smoke & DeLegge, 2008). A Chyle leak may manifest in different ways. The most common ones are Chylothorax (chylous effusion) into the thoracic cavity, as a chyloperitoneum (chylous ascites) into the abdomen, as a chylopericardium around the heart, or as external draining fistula. Treatment options for Chyle leak include drainage, pharmacological treatment (e.g. octreotide), direct surgical repair and nutrition intervention. The major goals in the nutritional management of Chyle leaks is to: decrease production and flow of Chyle (allow closure of the leak if possible), replenish fluid and electrolytes losses, and prevent malnutrition. The option for nutritional management is to use a low-fat oral diet in combination with MCT oil (prevent too much LCTs) (McCray & Parrish, 2011). The nutritional management strategy can be combined with the use of pharmacological treatment such as with octreotide. Unfortunately, to date, there is no consensus when to start and stop with octreotide therapy (Das & Shah, 2010).
The MCT strategy is frequently used in the case of Chyle leaks. As mentioned, MCTs do not require to be transported via the lymph system and therefore serves as an alternative fat source for patients with Chyle leaks. Note that despite MCTs not needing the lymph system, a very high MCT containing diet might still lead to some medium chain fatty acid presence in the lymph fluid (Jensen, Mascioli, & Meyer, 1989). Coconut oil should not be used in the management of Chyle leaks due to the high amount of LCTs present in the oil (McCray & Parrish, 2011). Similar with the other conditions, after >2-3 weeks the patient needs a source of essential fatty acids and most likely also additional fat-soluble vitamins. It is important to monitor patients with Chyle leaks on their nutritional status. Due to variety of leaks and underlying conditions, there is no common guideline possible.
It is very complicated to study prospectively the effect of MCT oils in patients with Chyle leaks due to the high variety of cases. Most evidence has been generated using retrospective data and case reports.
In a retrospective study of 245 patients that underwent pancreatoduodenectomy or total pancreatectomy, 40 patients who developed a Chyle leak were placed on an MCT-containing enteral formula, until they were able to transition to a fat-free diet with oral MCT supplementation. All patients experienced a decrease in Chyle output without requiring surgical intervention or parental nutrition (Abu Hilal, Layfield, & Di Fabio, 2013).
Another study looked retrospectively into the efficacy of MCT supplementation in an infant population developing chylothorax after congenital heart surgery. They concluded that MCT alone was effective in 71% of the patient (17 out of 24) (Biewer, et al., 2010).
In a recent case study, a 33-week preterm neonate with refractory congenital chylothorax was treated with octreotide and nourished with locally available skimmed milk fortified with MCT oil. The authors concluded that skimmed milk fortified with MCT oil is a cheap and safe alternative (Sahoo, Mangla, Sethi, & Thukral, 2018). A disadvantage when feeding an infant with chylothorax is the discontinuity of breast milk feeding. In a recent study, modified breast milk enriched with MCT oil (n=13) was compared to a normal MCT containing formula (n=10). The breast milk was centrifuged in order to remove the fat, mainly LCTs and after that fortified and enriched with MCT oil. The authors concluded that feeding the infants with this modified breast milk is efficient and unharmful in chylothorax patients following cardiac surgery. This protocol ensures that patients can keep getting the benefits (e.g. immunological properties) of breast milk (Neumann, Springer, Nieschke, Kostelka, & Dahnert, 2020). A retrospective study in Austria with 34 chylothorax patients also showed that a conservative therapy approach using the proper nutritional strategy (including MCT) and medicines is successful in most patients (Hermon, et al., 2019).