NHD Issue 149: Chyle leaks an overview

CLINICAL

CHYLE LEAKS: AN OVERVIEW This article discusses the aetiology, diagnosis and treatment of chyle leaks.

Louise Edwards Community Team Lead/Specialist Dietitian Louise is a Specialist Dietitian working for the Central Cheshire Integrated Care Partnership (CCICP). She is the Community Team Lead and is passionate about service improvement.

REFERENCES Please visit: https://www. nhdmag.com/ references.html

Working in district general hospitals, I had not come across anyone with a chyle leak until a recent discharge of a patient from a tertiary centre. The individual was discharged following a complicated post-operative stay from a subtotal oesophagectomy for a distal oesophageal adenocarcinoma. Postoperatively, the individual developed a chylous output from an intercostal drain and the volume was significant so that parenteral nutrition was indicated. When I met this individual, they had a fear of consuming fat due to the information they had been given in hospital. This led me to research chyle leaks, what they are and how they are treated.

Chyle leaks occur due to lymphatic injury which may happen as a result of trauma or surgery. Surgeries for which it may occur could be to the chest, the abdomen, the neck, pancreatic resections, etc.1 Although the incidence of chyle leak post-surgery is low (1%4%), this complication can present significant challenges.2 Although rare, it is well recognised as a complication after oesophageal surgery. Sjoerd et al (2005)8 found an association between a chyle leak developing and the presence of positive lymph nodes.

WHAT IS CHYLE?

Chyle is a milky looking substance due to the presence of fat globules. It is an alkaline fluid that is produced postdigestion of food. Bibby and Maskell (2014)3 report that ‘one litre of chyle contains 200 calories, up to 30g of fat and 30g of protein, as well as electrolytes including potassium, sodium, calcium and phosphate.’ It also contains fat soluble vitamins and lymphocytes.

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Its primary function is immunological, but it also functions to transport long-chain fatty acids, fat soluble vitamins and proteins.3 Two to four litres of chyle are transported from the lymphatic system every day.

The location of injury of the lymph vessels can lead a chyle leak to develop in different ways: chylothorax in the thoracic cavity, chyloperitoneum into the abdomen, chylopericardium around the heart, or as an external draining fistula.17 Chyle leakage is a serious complication, with a reported mortality rate varying from 0-50%.18 DIAGNOSIS, SYMPTOMS AND CONSEQUENCES

Individuals often present with symptoms of dyspnoea, chest pain and/ or tachycardia.2 Diagnosis of a chyle leak is made in the presence of chylomicrons in the draining pleural fluid. If the draining fluid contains >100mg/dL of triglycerides it is considered indicative of a chyle leak.19 Symptoms of chyle leak can include breathlessness in chylothorax, in relation to fluid accumulation.3 Dehydration may occur if the volume of leakage is significant and malnutrition is possible due to the loss of calorie and protein rich fluid. As chyle is key in the immunological response, immunosuppression can occur. Metabolic complications can occur due to the loss of fluid and electrolytes.4 WHERE IS CHYLE MADE?

Chyle is formed in the small intestine and is produced as part of the digestive process of fatty foods. The chyle consisting of lymph and chylomicrons is taken up by the lacteals, a type of

CLINICAL

Chyle is formed in the small intestine and is produced as part of the digestive process of fatty foods.

lymph vessel for distribution within the body.

Chyle eventually drains into the thoracic duct, which is a large lymphatic vessel found on the left side of the torso. If a chyle leak develops, the lymphatic vessels cannot heal. Continuing to consume fats means that chyle continues to be produced and the lymphatic vessels are unable to heal.

Smoke and Delegge (2008)2 report that there are ‘strong feelings among clinicians about the use of bowel rest, parenteral nutrition, or a low-fat enteral formula for the treatment of chyle leak; however, definitive evidence supporting one nutrition therapy over another does not exist.’

MANAGEMENT AND TREATMENT

Reviewing the literature, Octreotide may be used to support chyle leak closure as it reduces gastrointestinal blood flow and gastrointestinal hormone secretion.3 It is also suggested that Orlistat could also be given as an adjunct since it interferes with lipid metabolism in the duodenum and prevents lipid absorption,7 thus decreasing chyle production.

Daily management of chyle leaks includes fluid balance and review of electrolyte levels.5 Removal of fluid with percutaneous aspiration or drainage may be required to reduce symptoms, whilst long-term management is ongoing.3 Reviewing the articles, treatment options can include nutritional, surgical and pharmacological components. Delaney et al (2017)5 report that, ‘following surgery, management of a chyle leak depends on drain output, patient comorbidities, available institutional expertise and surgeon preference’.

They define a chyle leak as low output if <500ml/ day, or high if >500ml/day. Low output drains of <500ml/day are said to be treated effectively with conservative management, but those of a high output are likely to require surgical intervention.6

PHARMACOLOGY

NUTRITION

A nutrition management plan for chyle leaks is considered first-line management, with success rates of 80%.8 Reviewing the evidence, there are different approaches from a dietary perspective.

Steven and Carey (2015)20 reported that there was no significant difference between dietary approaches to treat chyle leaks and the rate in which they resolved.

Campisi et al (2013)9 say that all patients with suspected chyle leaks should be www.NHDmag.com November 2019 - Issue 149

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A fat-free diet would not be nutritionally complete; it would be rather unpalatable and difficult to adhere to, thus potentially contributing to malnutrition. A mediumchain fatty acid (MCFA) containing diet with multivitamin supplementation is suggested to be preferable to a non-fat diet.9 Some chyle leaks have been shown to resolve on a low-fat diet alone.10 A low-fat diet that is high in MCT (medium-chain triglycerides) may be successful in reducing the chyle leak. MCTs passively diffuse from the gastrointestinal tract to the portal system and are absorbed directly into portal circulation rather than being transported in lymph.3 As they bypass the lymphatic system, this results in decreased chyle flow, thus allowing the injury to heal faster. Delaney et al (2017)5 state that a MCFA diet alone does not stop chyle production.

If enteral tube feeding is indicated, a feed that is high in MCT would be the feed of choice. This feed would support in reducing chyle leak output as it would be absorbed via the portal vein and processed by the liver.

Some papers have suggested that all patients with chyle leakage should initially be started on a MCT/low-fat oral diet with total parenteral nutrition (TPN) then being considered if indicated. If the chyle output is persistent or high, then TPN is considered as it bypasses the lymphatic system, thus reducing/ not contributing to chyle production.11-13 Assessment is required to see if TPN is indicated given its associated cost, need for line access and risk of infection, etc.

Interestingly, Smith (2019)10 reports from her dietetic experience that a significant number of patients who are on TPN or enteral nutrition are kept nil by mouth (NBM) to reduce the amount of long-chain fatty acids being consumed.

However, she states that there is no justification for this and by doing so there is a risk of dehydration.

Clear fluids would not contribute to the chyle leak and thus could at least be considered for oral intake. Oral nutritional supplements that are classed as ‘clear’ could be considered also.

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SURGERY

Surgery is considered if other measures have been ineffective. References report that surgical re-exploration is considered when chyle output is >500-1000mls/day for five days.13-16 Sjoerd et al (2005)8 found that those individuals requiring reoperation had a chyle output of more than two litres per day and this continued for two days post conservative management commencing.

OTHER CONSERVATIVE MEASURES

Other conservative measures discussed by Delaney et al (2017)5 include bed rest, as chyle leakage is increased with physical activity, ensuring bowels are opening regularly and using a stool softener to reduce intrathoracic and intraabdominal pressure with bowel movement.

OUTCOMES

Developing a chyle leak increases patient morbidity and prolongs length of hospital stay. Sjoerd et al (2005)8 found that out of a sample of 536 patients who underwent oesophagectomy for malignant disease of the oesophagus, or gastro-oesophageal junction, 20 patients (3.7%) developed chyle leakage post-operatively. These patients as a result had significantly more pulmonary complications, longer intensive care unit stay, and thus a longer hospital stay.

Wakefield (2013)1 states that if ‘left untreated, the chyle leak would cause complications such as compression of surrounding tissues, impaired immunity due to the high content of lymphocytes present within chyle, and nutritional deficiencies due to the loss of calories, protein and fat soluble vitamins.’

For the patient I was seeing, enteral feeding with a high MCT feed was not successful alone to reduce chyle leakage and, due to the drainage of chyle remaining high, TPN was commenced. As the chyle leak resolved and the patient improved, an oral diet low in fat was commenced. The patient was fearful of foods that would contribute to chyle production.

On conducting an internet search, there seems to be very little patient information in regards to a low-fat diet for chyle leaks and perhaps emphasis on what foods can be eaten would be beneficial.