Chylothorax 

Updated: Jun 11, 2019
Author: Sasha D Adams, MD; Chief Editor: BS Anand, MD 

Overview

Background

Chylothorax refers to the presence of lymphatic fluid in the pleural space secondary to leakage from the thoracic duct or one of its main tributaries.[1, 2, 3, 4] This is a relatively rare condition that may develop as a complication of thoracic and esophageal surgery,[2] as well as from nontraumatic causes such as hematologic malignancies.

Chylothorax has no predilection for age or either sex. The prevalence of chylothorax after various cardiothoracic surgeries is 0.2-1%. Mortality and morbidity rates for cases of chylothorax are approximately 10% in major clinical medical centers. Early complications include severe cardiorespiratory and volemic conditions; over time, malnutrition and immunosuppression can occur.[2]

In 1875, H Quinke described the first traumatic chylothorax. In 1948, RS Lampson performed the first thoracic duct ligation.

See the images below.

This anteroposterior upright chest radiograph show This anteroposterior upright chest radiograph shows a massive left-sided pleural effusion with contralateral mediastinal shift. Image courtesy of Allen R Thomas, MD.
This computed tomography scan of the chest of a 3- This computed tomography scan of the chest of a 3-year old child reveals a left-sided effusion and underlying parenchymal infiltrate and atelectasis. Image courtesy of Ibrahim Abdulhamid, MD.

Etiopathophysiology

A tear or leak in the thoracic duct causes chylous fluid to collect in the pleural cavity, which can cause acute or chronic alterations in the pulmonary mechanics. In a normal adult, the thoracic duct transports up to 4 L of chyle per day, allowing a rapid and large accumulation of fluid in the chest.

Nontraumatic

Malignant etiologies account for more than 50% of chylothorax diagnoses and are separated into lymphomatous and nonlymphomatous causes. Lymphoma is the most common etiology, representing about 60% of all cases, with non-Hodgkin lymphoma more likely than Hodgkin lymphoma to cause chylothorax. By comparison, nonlymphomatous cases are rare.

Nonmalignant etiologies are separated into idiopathic, congenital, and miscellaneous. Clinicians must rule out all possible malignant causes before designating the chylothorax as idiopathic. Congenital chylothorax, involving multiple lymphatic vessel anomalies or thoracic cavity defects and potentially associated with other congenital anomalies, is the leading cause of pleural effusion in neonates.[5, 6] Miscellaneous causes include cirrhosis, tuberculosis, sarcoidosis, amyloidosis, and filariasis.

Traumatic

Trauma is the second leading cause of chylothorax (25%).

Iatrogenic injury to the thoracic duct has been reported with most thoracic procedures. In particular, cardiothoracic surgery has been associated with 69-85% of cases of chylothorax in children.[7]

Milonakis et al looked at their experience in managing chylothorax following congenital heart surgery. Of the 1341 children who underwent correction of congenital heart disease, 18 (1.3%) developed postoperative chylothorax, which was managed with a therapeutic protocol that included complete drainage of chyle collection and controlled nutrition. Six children received adjunctive somatostatin. When lymph leakage persisted (range, 2.5-14.7 mL/kg/d for 8-42 days) despite conservative management, surgical intervention was implemented. Once chylothorax resolved, a 6-week diet of medium-chain triglycerides was given.

No deaths occurred. Conservative therapy was effective in 15 patients (83.3%); 3 patients with persistent drainage required thoracotomy with pleurodesis to achieve resolution, 2 of whom had not had an effective response with previously attempted chemical pleurodesis with doxycycline (range of duration leakage, 5.1-7.4 mL/kg/d for 15-47 days).

In a retrospective study involving 392 pediatric patients (mean age, 97 days) who underwent surgical treatment of congenital heart disease to determine whether the site of insertion of central venous lines was associated with the occurrence of chylothorax after cardiac surgery, Borasino et al reported that the insertion of central venous lines in the upper body had an increased association with postosurgical chylothorax.[8] Overall, 62 of 392 patients (15.8%) developed postsurgical chylothorax; affected patients more frequently had central venous line sites in the upper body (P = 0.03), had higher RACHS-1 scores (risk assessment for congenital heart surgery) (P = 0.03), had longer bypass times (P = 0.02); and had longer cross-clamp times (P = 0.03). The investigators indicated that by avoiding the use of central venous lines in the internal jugular and subclavian veins, the incidence of chylothorax may be reduced in this setting.[8]

Nonsurgical traumatic injury is a rare cause, usually secondary to penetrating trauma.

Pseudochylothorax: Chylothorax must be distinguished from pseudochylothorax, or cholesterol pleurisy, which results from accumulation of cholesterol crystals in a chronic existing effusion. The most common cause of pseudochylothorax is chronic rheumatoid pleurisy, followed by tuberculosis and poorly treated empyema.

 

Presentation

History and Physical Examination

History

Usually, patients with chylothorax remain asymptomatic until a large amount of chyle accumulates in the pleural space.

The average latent period between the insult and the onset of symptoms is 7-10 days. Symptoms include the following:

  • Dyspnea

  • Tachypnea

  • Classic symptoms of pleural effusion

Rarely, patients may experience a rapid accumulation of fluid in the pleural space, causing a tension chylothorax. This is of particular concern following a pneumonectomy. These patients experience a rapid hemodynamic and respiratory compromise, similar to the classic tension pneumothorax.

Physical Examination

Findings on physical examination are nonspecific and include the following:

  • Decreased breath sounds

  • Shifting dullness

If the patient has an existing chest tube, drainage of 400-600 cc per 8-hour period is concerning for a chylous leak, particularly in postsurgical patients.

 

DDx

Diagnostic Considerations

Important considerations

The timing of surgical management is controversial and depends on the etiology of the chylothorax and the patient's overall condition.

Patients with postesophagectomy chylothorax have a 50-82% mortality rate if treated conservatively.

A malignant etiology of the chylothorax must be ruled out, as greater than 50% of cases are due to malignancy, of which lymphoma accounts for approximately 75% of cases, followed by lung carcinoma.

Other conditions to be considered

Other conditions to consider in patients with suspected chylothorax include the following:

  • Acquired immunodeficiency syndrome (AIDS)-related complex

  • Congestive heart failure

  • Exudative pleural effusion

  • Malignant pleural effusion

  • Pseudochylothorax

Differential Diagnoses

 

Workup

Laboratory Studies

The following laboratory studies are not required for diagnosis but are useful to determine the metabolic and nutritional status of the patient:

  • Serum electrolyte tests

  • Serum albumin test

  • Complete blood cell (CBC) count with differential to assess for lymphocyte depletion

Imaging Studies

Chest radiographic findings are nonspecific for chylothorax and indistinguishable from other causes of pleural effusion; however, they may help to rule out other causes of the patient's symptoms.[4] Determine if effusion is bilateral. Look for a mediastinal shift.

The 2017 American College of Radiology (ACR) Appropriateness Criteria indicates that if the etiology of the chylothorax is unknown, obtain computed tomography (CT) scanning or magnetic resonance imaging (MRI) of the chest and abdomen for evaluation of the lymphatic vessels, and to rule out vascular abnormalities and/or malignancy.[4] The addition of contrast medium to CT scanning of the chest and abdomen may be useful when venous thrombosis is a suspected cause for chylothorax.[4]

Lymphangiography is useful when the anatomy of the thoracic duct needs to be defined preoperatively or when the site of the leak is not clinically obvious, and it may facilitate minimally invasive management when it is being considered.[4] Lymphoscintigraphy is also useful for the localization of the leak, evaluation of the thoracic duct patency, and differentiation of partial from complete thoracic duct transection.[9]

Procedures

Thoracentesis and pleural fluid analysis are the criterion standards to establish a diagnosis of chylothorax. Alternatively, in a postsurgical patient, tube thoracostomy output can be analyzed.

Pleural fluid analysis for triglyceride content helps to confirm the diagnosis of chylothorax. Note the following:

  • A level greater than 110 mg/dL reflects a 99% chance that the fluid is chyle.

  • A level less than 50 mg/dL reflects only a 5% chance that the fluid is chyle.

  • If the level is 50-110 mg/dL, use lipoprotein analysis or inspect the pleural fluid for chylomicrons or cholesterol crystals.

  • A ratio of pleural fluid cholesterol to triglyceride of less than 1 is also diagnostic.

A fasting patient may have serous-appearing pleural fluid. To confirm the diagnosis, administer cream through a nasoenteric tube prior to fluid collection. The cream will change the chylous production from serous to the characteristic milky white fluid. This change is diagnostic for a chyle leak.

Chylothorax can be distinguished from pseudochylothorax by fluid analysis. In pseudochylothorax, the cholesterol level is greater than 200 mg/dL, no chylomicrons are present, and cholesterol crystals are seen at microscopy.

 

Treatment

Medical Care

Patients with chylothorax can be treated by conservative means or surgery. Certain principles are common to both treatment options, including treating the underlying cause, decreasing chyle production, draining and obliterating the pleural space, providing appropriate fluid and nutritional replacement, and instituting necessary respiratory care.[4] Congenital chylothorax typically involves supportive management and may include thoracostomy drainage.[6] Nontraumatic chylothorax may pose a management challenge owing to the fact that the site of the leak may occur in less predictable locations.[10]

Always consider conservative management,[9, 11, 12] because the thoracic duct leak closes spontaneously in nearly 50% of patients. Few or no symptoms and minimal chyle loss characterize these cases. Decompress the pleural space with tube thoracostomy or repeated thoracentesis to keep the lung expanded against the chest wall and mediastinum. Reduce chyle production by instituting total parenteral nutrition or a fat-restricted oral diet supplemented with medium-chain triglycerides.

Chemoradiation may promote resolution of chylothorax and should be used in patients with malignant chylothorax who are not surgical candidates.

Somatostatin, or its analogue octreotide, has been used with success in a number of pediatric cases of postoperative and iatrogenic chylothorax.[13, 14, 15, 16] Reported effective doses of intravenous somatostatin range from 3.5 to 12 mcg/kg/h. Care must be taken to watch for adverse effects of somatostatin therapy, including diarrhea, hypoglycemia, and hypotension.

Surgical Care

The timing of surgical management is controversial and depends on the etiology of the chylothorax and the patient's overall condition.[9, 17]

Preoperatively, localize the thoracic duct leak by means of lymphangiography, oral administration of cream, or injection of 1% Evans blue dye. Cream is high in long-chain fatty acids and works by increasing chyle flow. It is administered enterally at 60-90 mL/h for 3-6 hours until a change in the color of the pleural fluid is noted. Evans blue dye can either be injected into the web space of the toes for uptake into the lymphatic space or be added to cream to increase visualization. A postoperative management algorithm for children can be found in an article by Panthongviriyakul and Bines.[18]

Indications for surgical intervention include the following:

  • Chyle leak greater than 1 L/d for 5 days or a persistent leak for more than 2 weeks despite conservative management

  • Nutritional or metabolic complications, including electrolyte depletion and immunosuppression

  • Loculated chylothorax, fibrin clots, or trapped lung

  • Postesophagectomy chylothorax (Patients with this carry a high mortality rate if treated conservatively.)[19]

Surgical options depend on the site of injury and the etiology of the chylothorax.

Thoracic duct ligation

Thoracic duct ligation is the criterion standard. The duct is usually ligated between the eighth and twelfth thoracic vertebrae, just above the aortic hiatus. The approach is usually through the right chest, either by an open right thoracotomy or through a thoracoscope.[20, 21]

Caronia et al reported successful resolution of chylothorax in a 24 yr old man using a left approach. The leak, which was isolated within the left upper chest cavity and refractory to conservative treatment, was successfully closed between the descending thoracic aorta and the vertebral column through a left mini-thoracotomy. The authors concluded that alternative approaches to thoracic duct ligation should be considered when the standard approach is not feasible.[22]

Prophylactic thoracic duct ligation for reducing postoperative chylothorax during esophagectomy requires further investigation; findings from systematic reviews and meta-analyses appear to have been mixed as to whether it is effective[23]  or not.[24]

Thoracic duct ligation appears to be an effective option for persistent refractory chylothorax, and it may be a first-line option for cases of right-side effusion with an output rate over 20 mL/kg.[11]

Thoracoscopic parietal pleural clipping

A retrospective study (2002-2014) of 14 infants with congenital chylothorax suggests that thoracoscopic parietal pleural clipping may be safe and effective to disrupt the pleural lymphatic channel flow.[25] Of the infants who underwent the procedure (n = 6), chest tube output decreased from an average of 86.96 mL/kg/day 2 days before surgery to an average of 6.5 mL/kg/day 2 days after surgery.[25]

Other interventions

A pleuroperitoneal shunt can be successful for refractory chylothorax but can be complicated by infection and obstruction.[9]

Pleurodesis is often used for malignant chylothorax, but it will not work in a case of loculated chylothorax or a trapped lung.

Surgical pleurectomy is a treatment option.

Lymphatic embolization may be effective in patients with traumatic leak and pulmonary lymphatic perfusion syndrome.[26]

 

Questions & Answers