Chylothorax

Question 1

Anatomy of thoracic duct

Answer 1

• originates from cisterna chyli (T10-L3)
• enters thorax through aortic hiatus (T12)
• Course
  
  • anterior to vertebral bodies (between Ao and azygous vein)
  • posterior to esophagus
• Crosses midline to left: T4-5 (coursing to left of esophagus)
• Arches laterally at C7 (anteiror to SC artery, superficial to phrenic/anterior scalene)
• Passes behind carotid sheath and terminates into jugular-SC vein junction
  
  • Single branch (80%)
  • Multiple branches (20%)

Question 2

Lymphatic drainage of right head, neck, chest wall, right lung, right heart, dome of liver, right diaphragm

Answer 2

Right lymphatic duct that drains into posterior junction of RIGHT jugular-SC junction

Question 3

Primary physiologic role of the thoracic duct

Answer 3

Deliver digestive fat (60% of ingested fat) to the venous system

Question 4

Main cellular component of thoracic duct lymph

Answer 4

T-lymphocytes

Question 5

Properties of chyle

Answer 5

• Bacteriostatic
• alkaline pH

Question 6

Normal rate of lymph flow

Answer 6

30-190 ml/hr

Question 7

Mechanics of normal lymph flow

Answer 7

• Negative transdiaphragmatic pressure gradient
• Thoracic duct valves
• Normal intraductal pressure: 10-25 cmH2O

Question 8

MCC of pleural effusion in neonatal period

Answer 8

Congenital Chylothorax

• Respiratory distress at birh or 1st weeks of life
• MOA:
  
  • atretic thoracic duct
  • multiple dilated lymphatic channels of fistulas
• Tx: conservative (self limited)
  
  • Breastfeeding ok
  • Thoracocentesis for inital relief
• Pleuroperitoneal shunting for persistent chylothorax (in absence of ascites)

Question 9

MC non-penetrating traumatic MOA of thoracic duct injury

Answer 9

Hyperextension of the spine with rupture of thoracic duct just above the diaphragm

Question 10

MC operations associated with surgical injuries to the thoracic duct

Answer 10

• Esophagectomy
• Aortic operations
• PDA ligation
• Left pneumonectomy
• Resection of posterior mediastinal tumors
• Sympathectomy

Question 11

Laterality of duct injuries above (and below) T6

Answer 11

• Right side: below T6
• Left side above T6

Question 12

Incidence of chylothorax after esophagectomy

Answer 12

0.5-3.5%

*no assocation with approach

Question 13

MOA of neoplastic chylothorax

MC neoplasm associated with chylothorax

Answer 13

Invasion, compression or tumor embolism of thoracic duct

Lymphoma (50% of cases)

Question 14

Most postoperative chylothoracies drain how much

Answer 14

Excess of 1L/day

*If persists for > 1 week, mortality and morbidity increased

Question 15

Spontaneous healing of non-surgical thoracic duct fistula occurs __ %

Answer 15

< 50%

Question 16

Laboratory (diagnostic) characteristics of chylothorax

Answer 16

Pleural fluid with:

• Triglyceride level > 110 mg/dL (99% diagnostic)
  
  • <50 ml/dL excludes chylothorax with 95% probability
  • 50-110 ml/dL: check chylomicrons
• Chylomicrons: very specific finding for chylothorax
• Fat staining with Sudan-3
• Cholesterol : Triglyceride ratio < 1

Question 17

Pseudochylothorax

Answer 17

Accumulation of cholesterol in long-standing pleural effusion.

Cholesterol > 200 mg/dL with cholesterol crystals (no chylomicrons)

Question 18

Medical managment of chylothorax

Answer 18

• Drainage of pleural space
• Reduction of chyle flow (somatostatin)
• Hydration
• Nutrition (medium-chain triglycerides)
  
  • Reduction in dietary intake and long-chain f.a.
  • TPN may be preferred
• ~ 25-50% spontaneous closure rate
• Infection rare as chyle is bacteriostatic

Question 19

Surgical treatment options for chylothorax

Answer 19

• Pleurodesis (chemical)
  
  • fistula healing likely due to obliteration of pleural space rather than vessel closure
• Pleuroperitoneal shunting (no ascites)
  
  • malignant chylothorax
  • thoracotomy contraindicated
• Percutaneous transabdominal duct catheterization and embolization
  
  • frail pateints not able to tolerate duct ligation
• Thoracic duct ligation

Question 20

Indications for thoracic duct ligation

Answer 20

• Thoracic duct drainage > 1500 ml/day (adults) or > 100 ml/day (children) over 5 day period despite medical managment
• Persistent leak > 2 weeks
• Nutritional or metabolic complicaitons
• Entrapped lung with inability to drain collection with thoracostomy
• Post-esophagectomy chylothorax
  
  • high morbidity and mortality due to immunologic and metaboic imbalances

Question 21

Surgical techniques to address thoracic duct

Answer 21

• Direct ligation of thorcic duct
• Mass ligation
  
  • all tissue between Ao, spine, esophagus and azygous vein
  • performed above diaphragmatic hiatus (right pleural space)
• VATS ligation
• Pleurectomy
• Fibrin glue
• Pleuroperitonal shunt

Question 22

Visualization of thoracic duct can be enhanced by what measures

Answer 22

Ingestion of 6-8 oz of cream or olive oil 2-3 hours prior to surgery

Question 23

Effect of thoracic duct ligation on mortality

Answer 23

Reduction in mortality from >50% to ~ 10%

Prophylactic thoracic duct ligation advocated during esophagectomy