Chylothorax

Reviewed and revised 8 September 2014

OVERVIEW

  • Chylothorax occurs when chyle from the thoracic duct empties into the pleural space
  • Chyle is a milky white fluid with a high concentration of triglycerides, chylomicrons, and white blood cells
  • Pseudochylothorax is pleural fluid that mimics true chylous pleural effusion in appearance but lacks the biochemical criteria for chylothorax; usually due to a longstanding pleural effusion

ANATOMY

The primary function of the thoracic duct is to transport digestive fat (~70% of total) to the venous system but also serves as a major route of lymphatic drainage in the human body

  • Thoracic duct transports the chyle from the cisterna chyli into the circulatory system, usually into the junction of the left jugular and subclavian veins
  • one thoracic duct arises from the cisterna chyli and ascends through the aortic hiatus on the anterior surface of the vertebral bodies between the aorta and azygos vein (~50% of people, there is considerable anatomic variation)
  • the thoracic duct has extensive lymphatic and venous communications
  • Between the cisterna chyli and the central venous system, the thoracic duct runs in close proximity to various anatomical structures including the oesophagus, lungs, aorta, vertebrae and lymph nodes

CAUSES

  • Iatrogenic — most common; e.g. post-esophagectomy, lymphatic fistula formation
  • Trauma — 20%; e.g. penetrating trauma, fracture-dislocation of the spine
  • Subclavian venous thrombosis
  • Neoplasia (e.g. lymphoma)
  • Idiopathic
  • Infection — Filariasis, Tuberculosis
  • Congenital and acquired lymphatic disorders ( e.g. Intestinal lymphangiectasia, Lymphangiomyomatosis)
  • Mediastinal lymphadenopathy
  • Chylous ascites (e.g. cirrhosis, pancreatitis, other causes of chylothorax affecting abdominal lymphatics)

CLINICAL FEATURES

  • milky white opalescent pleural aspirate (can be clear, depending on nutritional state)
  • 80% unilateral
  • if traumatic/ iatrogenic there is often a latency period of 2–7 days between the time of injury and clinical evidence of chylothorax (unless there is a major injury)
  • respiratory embarrassment (dyspnea, cough, chest discomfort)
  • complications such as poor nutritional state, immunocompromise and hypovolaemia
  • features of the underlying cause

Fever and pleuritic pain are rare as chyle is non-irritating to the pleura

INVESTIGATION

Pleural aspirate analysis

  • appearance
  • presence of chylomicrons is diagnostic
  • pleural fluid triglyceride level >110 mg/dL (though 15% have less)
  • protein-discordant (high protein and low LDH levels) exudate unless additional cause of transudate is present (e.g. CHF, cirrhosis)

Imaging

  • CXR
  • CT chest
  • conventional lymphangiography or lymphoscintigraphy (role is poorly defined, often little impact on management)

Investigations to diagnose underlying cause

MANAGEMENT

Overview

  • tailor management to cause, clinical context (size of the effusion, the rate of accumulation, clinical effects, comorbidities) and available expertise
  • non-surgical management is effective in about 50% of traumatic chlylothoax cases, but only a minority of non-traumatic cases
  • surgical treatment is generally indicated if non-operative treatment is unsuccessful at 2 weeks
  • surgical intervention offers better results than conservative management when the daily chyle leak exceeds 1.5 l in an adult or >100 ml/kg body weight per day in a child
  • malignant causes are generally managed conservatively

Maintaining Nutrition and Reducing the Volume of Chyle Circulation

  • Dietary: medium-chain fatty acid diet (absorbed directly into portal vein) or total parenteral nutrition (resolves 50% of congenital and traumatic chylothoraces)
  • Octreotide

Relieving Dyspnea by Removing Chyle from the Pleural Cavity

  • Thoracentesis (short term only)
  • Tube thoracostomy (short term only)
  • Pleuroperitoneal or pleurovenous shunting
  • Pleurodesis

Treatment of the Underlying Defect

  • Thoracic duct embolization
  • Ligation of the thoracic duct (thoracoscopy or thoracotomy)
  • Clipping or fibrin glue to the thoracic duct leak
  • Radiotherapy for mediastinal lymphoma
  • Flap coverage

Other suggested therapies

  • alpha agonists to cause lymphatic constriction, e.g. etilifrine, midodrine

Supportive care and monitoring

OTHER INFORMATION

  • chylothorax is the most common type of pleural effusion in neonates, due to: persistent fetal chylothorax, rupture of the thoracic duct from trauma during delivery, or to developmental abnormalities of the thoracic duct.

References and Links

Journal articles

  • Nair SK, Petko M, Hayward MP. Aetiology and management of chylothorax in adults. Eur J Cardiothorac Surg. 2007 Aug;32(2):362-9. PMID: 17580118. [Free Full Text]

FOAM and web resources


CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

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