Chylothorax Flashcards

1
Q

Anatomy of thoracic duct

A
  • 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%)
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2
Q

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

A

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

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3
Q

Primary physiologic role of the thoracic duct

A

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

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4
Q

Main cellular component of thoracic duct lymph

A

T-lymphocytes

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5
Q

Properties of chyle

A
  • Bacteriostatic
  • alkaline pH
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6
Q

Normal rate of lymph flow

A

30-190 ml/hr

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7
Q

Mechanics of normal lymph flow

A
  • Negative transdiaphragmatic pressure gradient
  • Thoracic duct valves
  • Normal intraductal pressure: 10-25 cmH2O
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8
Q

MCC of pleural effusion in neonatal period

A

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)
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9
Q

MC non-penetrating traumatic MOA of thoracic duct injury

A

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

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10
Q

MC operations associated with surgical injuries to the thoracic duct

A
  • Esophagectomy
  • Aortic operations
  • PDA ligation
  • Left pneumonectomy
  • Resection of posterior mediastinal tumors
  • Sympathectomy
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11
Q

Laterality of duct injuries above (and below) T6

A
  • Right side: below T6
  • Left side above T6
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12
Q

Incidence of chylothorax after esophagectomy

A

0.5-3.5%

*no assocation with approach

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13
Q

MOA of neoplastic chylothorax

MC neoplasm associated with chylothorax

A

Invasion, compression or tumor embolism of thoracic duct

Lymphoma (50% of cases)

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14
Q

Most postoperative chylothoracies drain how much

A

Excess of 1L/day

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

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15
Q

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

A

< 50%

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16
Q

Laboratory (diagnostic) characteristics of chylothorax

A

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
17
Q

Pseudochylothorax

A

Accumulation of cholesterol in long-standing pleural effusion.

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

18
Q

Medical managment of chylothorax

A
  • 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
19
Q

Surgical treatment options for chylothorax

A
  • 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
20
Q

Indications for thoracic duct ligation

A
  • 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
21
Q

Surgical techniques to address thoracic duct

A
  • 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
22
Q

Visualization of thoracic duct can be enhanced by what measures

A

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

23
Q

Effect of thoracic duct ligation on mortality

A

Reduction in mortality from >50% to ~ 10%

Prophylactic thoracic duct ligation advocated during esophagectomy

24
Q

Describe how to ligate the thoracic duct?

A

Right thoracotomy.

Elevation of the soft tissue intervening between the esophagus on the right, the azygos vein on the left and the descending thoracic aorta and vertebral column deep to the operative field is performed with a Debakey forceps. It is this intervening tissue which contains the thoracic duct, including a plexus of lacteals. This soft tissue is then ligated in 3 positions at 2 cm increments starting approximately 2 cm above the esophageal hiatus of the diaphragm.

25
Q
A