To the editor:
Chylothorax is an accumulation of lymph (containing a great amount of lymphocytes, triglycerides, and chylomicrons) in the pleura as a consequence of impaired drainage of the thoracic duct. Chylothorax may result from traumatic or non-traumatic causes (such as neoplasms, sarcoidosis, chest irradiation, etc.), but there are also idiopathic forms.1,2
The thoracic duct may be damaged during placement of central catheters or as the result of stenosis or thrombosis of the thoracic veins caused by the catheter.3 However, it is noteworthy that very few cases have been reported in the literature despite the enormous number of catheters placed.4
The case of a female patient on haemodialysis who developed chylothorax secondary to a superior vena cava lesion related to the presence of a right jugular catheter is reported here.
CASE REPORT
A 72-year old female patient included in a regular haemodialysis programme in April 2004 because of chronic kidney disease secondary to diabetic nephropathy. The patient had many vascular access problems since she entered the programme. She was initially placed a tunnelled right jugular catheter. In May 2004, a brachiocephalic arteriovenous fistula was performed in the upper limb, but experienced early thrombosis. A vascular study considered a new fistula or prosthesis unfeasible. In May 2005, oral anticoagulant therapy was started due to catheter dysfunction. An angio-MRI (fig. 1) showed stenosis of the right internal jugular and superior cava veins. The superior vena cava was dilated and a tunnelled catheter was placed through the right jugular vein with the tip at inferior cava level, which allowed for continuing haemodialysis therapy.
In November 2005, the patient experienced a gradual increase in dyspnoea until she also suffered dyspnoea at rest. Chest x-rays showed a right pleural effusion with no fever or signs of infection. Laboratory test results included a WBC count of 9130/mm3, haemoglobin 14.3 g/dL, creatinine 6 mg/dL, glucose 125 mg/dL, total protein 61.2 g/L, LDH 120 IU/L, triglycerides 237 mg/dL, and cholesterol 178 mg/dL; Kt/V was 1.7 and protein catabolic rate (PCR) 0.86. A thoracentesis yielded a milky fluid with 1620 cells/mm3 (95% lymphocytes), glucose 128 mg/dL, protein 34 g/L, LDH 86 IU/L, triglycerides 754 mg/dL, pH 7.43, and adenosine deaminase 15 IU/L. Cytology was benign and culture was sterile.
Based on a diagnosis of chylothorax, a pleural draining tube was placed and pleurodesis with talc was attempted, but was ineffective. In March 2006, the patient was admitted for right upper lobe pneumonia that improved on antibiotic therapy. A CT scan of the chest showed an encapsulated pleural effusion, with prevented pleurodesis. Videothoracoscopy was considered but was rejected by the patient, who subsequently died from septic shock of a pulmonary origin. Necropsy was not authorised.
DISCUSSION
Patients on haemodialysis may experience pleural effusion due to highly diverse causes.4 While exudates may occur in the setting of infections, neoplasms, uremic pleuritis, or haemothorax, transudates due to volume overload or an impaired venous drainage occur in most cases.4-7 Occurrence of chylothorax in patients on haemodialysis is very uncommon.4
The cause of chylothorax in the reported patient is difficult to establish, but caval stenosis or a direct lesion to the thoracic duct may have possibly been involved in its pathogenesis.8,9 Diagnosis was confirmed based on the milky appearance and composition of the fluid (triglyceride levels higher than 110 mg/dL and elevated lymphocyte count). Treatment of chylothorax is controversial and depends on both its cause and symptoms. The approach may range from conservative treatment to elective surgery.10 A low fat diet with medium chain triglycerides (that are directly absorbed to blood) is advised to decrease the amount of lymph. Chemical pleurodesis using tetracycline, bleomycin, or talc, and pleuroperitoneal shunts have been shown to be useful.10 In patients with vena cava obstruction, angioplasty may solve the problem.11 Surgery by minimally invasive thoracoscopy with supradiaphragmatic repair or ligation of the thoracic duct may correct chylothorax.2,10,12 In order to prevent infectious complications and malnutrition, chylothorax fluid has been successfully reinfused during haemodialysis in some patients.4
To sum up, chylothorax associated to central catheters for haemodialysis is uncommon and requires adequate diagnostic evaluation and a specific therapeutic approach.
