Pleural Effusion-Chylothorax

Epidemiology

  • Definition: chylothorax is the presence of chylus (lymph) in the pleural space due to damage to the thoracic duct

Etiology

Neoplasm

  • General Comments: neoplasms account for >50% of cases
  • Lymphoma (see Lymphoma, [[Lymphoma]]): most common non-traumatic etiology (represents 75% of malignancy-associated cases)
    • Likely results from lymphoma cells invading the wall of the thoracic duct
    • Lymphoma cells are typically not seen in pleural biopsies or biopsies of the thoracic duct
  • Lung Cancer (see Lung Cancer, [[Lung Cancer]])
  • Kaposi Sarcoma (see Kaposi Sarcoma, [[Kaposi Sarcoma]])
  • Other Malignancies
  • Benign Tumors

Traumatic Chylothorax

General Comments

  • Trauma is 2nd Most Common Etiology of Chylothorax

Surgery/Procedures

  • General Comments: especially common with intrathoracic procedures which involve the left subclavian artery
  • Cardiothoracic Surgery (0.5% incidence): including thoracoscopy
  • Central Venous Catheter (CVC) (see Central Venous Catheter, [[Central Venous Catheter]])
  • Cervical Node Dissection
  • Esophageal Resection (2% incidence): especially transhiatal approach
  • Esophagogastroduodenoscopy (EGD) with Variceal Sclerotherapy (see Esophagogastroduodenoscopy, [[Esophagogastroduodenoscopy]])
  • High Translumbar Aortogram
  • Peritoneovenous Shunt (LeVeen Shunt) with Superior Vena Cava Obstruction (see Peritoneovenous Shunt, [[Peritoneovenous Shunt]])
  • Pneumonectomy
  • Sellate Ganglion Blockade
  • Subclavian Vein Central Venous Catheter in the Presence of Thrombosis (see Central Venous Catheter, [[Central Venous Catheter]])
  • Thoracic Sympathectomy

Trauma

  • General Comments: closed-traumatic disruptions usually occur on right side near T9-T10
  • Childbirth
  • Coughing
  • Head and Neck Surgery
  • Hiccuping
  • Hyperextension of Spine
  • Penetrating Injury of Neck or Thorax
  • Straining
  • Stretching While Yawning
  • Vertebral Fracture: especially after fatty meal
  • Vomiting (see Nausea and Vomiting, [[Nausea and Vomiting]])
  • Weight Lifting

Neonatal Chylothorax

  • Most common cause of pleural effusion in first few days of life
    • Usually right-sided or bilateral
    • Possibly due to increased fetal venous pressure during delivery
    • Increased incidence with hydramnios

Idiopathic Chylothorax

  • General Comments: accounts for 15% of cases

Other

  • Amyloidosis (see Amyloidosis, [[Amyloidosis]])
  • Behcet’s Disease (see Behcet’s Disease, [[Behcets Disease]])
  • Congenital Chylothorax: due to congenital malformation of thoracic duct (although can also be observed after traumatic childbirth)
  • Congestive Heart Failure (CHF) (see Congestive Heart Failure, [[Congestive Heart Failure]]): with increased central venous pressure
  • Fibrosing Mediastinitis (see Granulomatous Mediastinitis and Fibrosing Mediastinitis, [[Granulomatous Mediastinitis and Fibrosing Mediastinitis]])
  • Filiariasis
  • Hemangiomatosis (Gorham’s Syndrome)
  • Intestinal Lymphangiectasia (Noonan’s Syndrome)
  • Lymphangioleiomyomatosis (see Lymphangioleiomyomatosis, [[Lymphangioleiomyomatosis]]): occurs in 28% of cases
  • Mediastinal Lymphadenopathy (see Mediastinal Mass, [[Mediastinal Mass]])
  • Other Central Vein Thrombosis
  • Radiation Therapy (see Radiation Therapy, [[Radiation Therapy]]): often late sequela
  • Retrosternal Goiter
  • Sarcoidosis (see Sarcoidosis, [[Sarcoidosis]])e
  • Superior Vena Cava (SVC) Syndrome (see Superior Vena Cava Syndrome, [[Superior Vena Cava Syndrome]])
  • Thoracic Aortic Aneurysm (see Thoracic Aortic Aneurysm, [[Thoracic Aortic Aneurysm]]): due to erosion of thoracic duct
  • Thoracic Duct Lymphangitis
  • Transdiaphragmatic Movement of Chylous Ascites
  • Tuberculosis (see Tuberculosis, [[Tuberculosis]]): with mediastial involvement
  • Tuberous Sclerosis (see Tuberous Sclerosis, [[Tuberous Sclerosis]])
  • Yellow Nail Syndrome (see Yellow Nail Syndrome, [[Yellow Nail Syndrome]])

Physiology

  • Anatomy (note that anatomy is variable with anomalous course in 60% of humans): lymph vessels from lower extremities and peritoneal cavity join together behind the aorta and inferior to the diaphragm to form the cisterna chyli, the origina of the thoracic duct -> thoracic duct passes through diaphragm and runs along the right paravertebral space (between the azygos vein and the aorta
    • At the 3rd-4th vertebra, thoracic duct crosses into the left thorax
    • Thoracic duct then turns laterally and makes a small loop in the neck region
    • Thoracic duct usually empties into the left subclavian vein, between jugular and vertebral veins (however, anatomic variably occurs and it can empty into the right subclavian vein)
    • Thoracic duct has valves (with thoracic motion causing forward movement of the chyle) -> allows chyle to only move forward through the duct
    • There are numerous small connections of thoracic duct with veins -> this allows duct to be ligated safely
  • Chyle contains triglycerides, chylomicrons, protein, and lymphocytes (originating from the GI tract) -> chyle is bacteriostatic
    • Normal chyle flow is 2L per day
    • Chyle production increases with PO intake
    • Chyle contains chylomicrons, composed of long-chain triglycerides
  • Chylothorax results from obstruction or disruption of the thoracic duct
  • Chylothorax is usually right-sided: since most of the duct is within the right hemithorax
    • If thoracic duct injury occurs at the level of the aorta -> left chylothorax can occur
    • If thoracic duct injury occurs at point of crossover in the thorax -> bil chylothorax can occur
  • Note: ligation of thoracic duct does not produce chylothorax (due to collaterals and lymphatico-venous anastomoses)

Diagnosis

  • CXR/Chest CT
    • Pleural effusion (usually right-sided)
    • Chest/Abd/Pelvic CT is necessary to exclude intrathoracic tumor (particularly lymphoma)
      CXR/Chest CT patterns: chyloma may occur in posterior mediastinum before chylothorax develops (disappears when mediastinal pleura ruptures into pleural space)
      -Pleura is normal (chyle is non-irritating)
  • Lymphangiogram
    • Useful in some cases to demonstrate if disease is localized of diffuse
    • May demonstrate leak or level of obstruction
  • Pleural Fluid:
    • Appearance: ususlly appears thick, opalescent, whitish or coffee-colored, due to high fat content (however, only 47% of cases demonstrate the characteristic odorless, milky, turbid fluid of chylothorax)
      • Neonatal chylothorax is serous until milk is fed
    • Triglyceride: elevated
      • Trig >100 mg/dL: diagnoses chylothorax (chylothorax fluid clears with addition of ethyl ether)
      • Trig <50 mg/dL: rules out chylothorax
      • Trig 50-110 mg/dL: perform lipoprotein analysis for chylomicrons to diagnose chylothorax
    • Chylomicron: positive
    • Centrfugation: will not clear fluid in chylothorax (as opposed to in empyema, where centrifugation will sediment the cells result in a clear supernatant)
    • LDH:
    • Total Protein: usually >30 g/L
    • Electrolytes: same as serum
    • Cells: mostly T-cells
    • Ethyl Ether: causes clearing of fluid

Clinical Manifestations

Chyloma

  • Epidemiology: this presentation is more common after traumatic thoracic duct injury
  • Physiology: local chyle collection that forms acutely in the chest
    • Chyle subsequently migrates into mediastinum (chylomediastinum), pericarium (chylopericardium), or into the pleural space (chylothorax)
  • Clinical
    • Acute Chest Pain (see Chest Pain, [[Chest Pain]])
    • Dyspnea (see Dyspnea, [[Dyspnea]])
    • Swelling in Supraclavicular Fossa: occasional
    • Tachycardia (see Sinus Tachycardia, [[Sinus Tachycardia]])

Pleural Effusion

  • Epidemiology: typical presentation
  • Clinical
    • Onset
      • Non-Traumatic Cases: gradual onset
      • Traumatic Cases: subacute onset
      • May be acute with associated hypotension in some cases
    • Rate of Chyle Accumulation: rate of accumulation depends on diet
      • High Fat Meal: increases chyle flow 2-10x normal for several hrs
      • Ingestion of Liquid (But not Carbohydrate or Protein): increases chyle flow
    • Absence of Chest Pain and Fever: chyle is non-irritating and bacteriostatic
    • Atelectasis (see Atelectasis, [[Atelectasis]]): may be present
    • Increased Risk of Infection: due to loss of lypmhocytes in chyle
    • Nutritional Depletion: due to loss of protein, water, electrolytes, fats) -> exacerbated by thoracenteses, chest tube
  • Treatment
    • Accumulation After Thoracentesis: rapidly reaccumulates

Treatment

Dietary Modification with Observation

  • Low-Fat Diet (with medium-chain triglycerides, which are predominantly absorbed drectly in to the blood): may decrease chyle flow
  • TPN: may decrease chyle flow
  • In traumatic cases, approximately 50% of chylothoraces will heal with conservative management

Chemical Pleurodesis

  • Pleurodesis (with tetracycline, bleo, talc): may be necessary, especially for malignancy-associated cases
  • It is generally believed that pleurodesis success rates are lower in chylothorax than for other malignant effusions

Pleuroperitoneal Shunt

  • May be considered early to avoid malnutrition (especially in idiopathic cases)
  • Contraindication: co-existent chylous ascites
  • Requires daily pumping by the patient
  • May require replacement, in cases where shunt fails to function

Thoracoscopic Ligation of the Thoracic Duct

  • Ligation of duct just above the diaphragm
  • Usually successful and well-tolerated (due to collaterals from thoracic duct into other veins)

Mediastinal XRT

  • Usually effective (in 68% of lymphoma cases and 50% of metastatic cancer cases)

References

  • Eur Resp J 1997 ; vol. 10 no. 5 1157-1162
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