Diagnosis and management of traumatic bilateral chylothorax: a clinical conundrum

Abstract

A 35-year-old man was admitted in the emergency department with a complaint of progressive dyspnoea and 4-day prior history of a road traffic accident. An initial evaluation was inconspicuous and he was discharged. Clinical examination and radiological imaging suggested bilateral pleural effusion for which bilateral intercostal drains were inserted. Further pleural fluid analysis aided the diagnosis of bilateral chylothorax. A conservative approach consisting of a fat-free diet, total parenteral nutrition and octreotide therapy was started. Upon failure of conservative management, thoracic duct ligation by thoracotomy was done. Chylous output decreased dramatically and subsequently, and the patient was discharged in a healthy condition. This case illustrates intricacies involved in the diagnosis and management of traumatic chylothorax. Also, conservative treatment forms the first line of management, but if ineffective, then early surgical intervention should be considered. Early diagnosis and timely intervention are keystone factors for a better outcome.

Background

Bartolet described the first case of chylothorax in 1633^{1 2} as a ‘rare condition with grave prognosis’ where lymphatic fluid leaks into the pleural cavity from the thoracic duct. Most often, the cause is iatrogenic and traumatic chylothorax is very rare with an incidence of 0.2%–3% after blunt thoracic trauma and 0.9%–1.9% after penetrating trauma.^{3 4} The occurrence of massive bilateral chylothorax after blunt thoracic trauma is exceedingly rare, thus evading early diagnosis usually. There is a high risk of the condition being fatal, with no clearly defined management guidelines.

Diagnosing chylothorax early is an onerous task, with reported median time duration from causation to the diagnosis being 7 days.⁵ Chylothorax can lead to immediate, severe consequences such as respiratory compromise, dyselectrolytaemia, malnutrition and lymphopaenia leading to immunosuppression. The condition undoubtedly mandates early detection and prompt intervention at the earliest.

Management of chylothorax is still unclear and varies from non-operative means to either radiological or surgical intervention. Conservative treatment consists of intercostal tube thoracostomy to drain the chylous fluid, keeping the patient nil per oral, giving somatostatin analogues to allow regression of the chylous output and addressing malnutrition by starting total parenteral nutrition (TPN) or medium-chain triglyceride (MCT) diet.

With the conservative approach, success rates of up to 88% have been achieved.⁶ In some cases where conservative therapy fails, treatment options consist of either percutaneous thoracic duct embolisation (TDE) or thoracotomy/thoracoscopic-assisted ligation of the thoracic duct. We report a case of massive bilateral chylothorax following a blunt trauma chest which proved to be a surgical challenge in terms of both diagnosis and treatment.

Case presentation

A 35-year-old man presented to the emergency department of Dayanand Medical College and Hospital which is a tertiary care hospital with progressive dyspnoea since 1 day which was sudden in onset. The patient had a history of road traffic accident 4 days prior to admission. Following the accident, patient received first aid and underwent preliminary examination which included chest roentgenogram (X-ray). In the absence of any significant clinical or radiological findings, patient was discharged at that time. Later patient was received in respiratory distress on fourth day post-trauma with room air saturation at 75%. His haemodynamic parameters were normal with a blood pressure of 110/70 mm Hg and pulse rate of 68 bpm. The patient was immediately intubated and put on ventilatory support. On clinical examination, air entry was comparatively decreased on right side. In addition, there were no other supplementary findings.

Investigations

First chest X-ray (figure 1) was done after blunt trauma revealed normal study. Chest X-ray done immediately following initial resuscitation in the emergency on fourth post-trauma day revealed significant pleural effusion on the right side without any rib fractures (figure 2). This was followed by the insertion of an intercostal drain (ICD) on the right side. Post ICD insertion chest X-ray showed expanded lung on the right side with egress of the pleural fluid. In order to find out the underlying aetiology, a CT scan of chest and abdomen (figure 3) was done which was suggestive of bilateral multiple posterior rib fractures with significant pleural effusion bilaterally with underlying lung contusions and fracture of the transverse process of L1 and L2 vertebra on the left side. ICD was inserted on the left side and in total, about 4 L of thick milky white fluid was drained from both the pleural cavities. Figure 4 shows a chest X-ray with right-sided haziness and bilateral ICD in situ.

Figure 1.

First chest X-ray after the trauma showing no abnormal finding.

Figure 2.

Chest X-ray after emergency right-sided ICD insertion (blue arrow). ICD, intercostal drain.

Figure 3.

CT scan of chest and abdomen showing significant bilateral pleural effusion (blue arrows) with tip of the ICD seen inside the right pleural cavity (red arrow). ICD, intercostal drain.

Figure 4.

Chest X-ray after bilateral ICD insertion (blue arrow). ICD, intercostal drain.

Furthermore, pleural fluid analysis was affirmative of the diagnosis of chylothorax revealing triglyceride level of 1200 mg/dL, total leucocyte count of 0.3x10⁹ cells/L, albumin level of 0.5 g/dL, glucose level of 156 mg/dL, total protein of 3.2 g/dL and lactate dehydrogenase of 233 U/L, with absence of red blood cells, malignant cells and any growth on microbiological examination. Also, the fluid retained its white colour on the addition of 2 mL of ethyl ether.

Differential diagnosis

It is important to differentiate chylothorax from haemothorax as both are indistinguishable on chest X-ray. However, the examination of the pleural fluid after aspiration helped in differentiating haemothorax (bright red to dark red in colour) from chylothorax (milky white in colour). Also, empyema and cholesterol effusion may have milky white effusions just like chylothorax. In empyema the milky white colour is due to suspended leukocytes, therefore on pleural fluid centrifugation the supernatant in empyema is clear whereas opaque in the case of chylothorax. Cholesterol effusion or pseudochylothorax consists of a high concentration of cholesterol in pleural fluid and occurs in chronic pleural inflammatory/infective disorders. On adding 2 mL of ethyl ether to the pleural fluid, the milky white colour disappears in the case of pseudochylothorax,⁴ thus differentiating the two conditions.

Treatment

Subsequent to pleural fluid analysis, the diagnosis of bilateral traumatic chylothorax was made. It was possible to extubate the patient the following day after successfully evacuating both the pleural cavities of the chylous fluid. The patient was initially managed conservatively with TPN containing essential fatty acids, proteins, amino acids and electrolytes. Also, subcutaneous octreotide administration was commenced along with a fat-free and MCT diet. Despite the medical management, pleural fluid output remained high at more than 1 L/day even after 10 days. At this point, a decision was made to intervene either radiologically or surgically. However, no active chyle leak could be established on angiography. With surgery being the last resort, the patient underwent ligation of thoracic duct by right-sided thoracotomy. Postoperatively, the output from the drains decreased gradually resulting in the removal of left and right ICD on sixth and eighth postoperative day, respectively. The patient was discharged the next day without any complications.

Outcome and follow-up

The patient was discharged on the ninth postoperative day which was 20 days after hospital admission. After getting discharged, the patient was followed up for a period of 2 months. He did not experience any complications or sequelae with his health being completely restored. He was able to resume his daily routine activity 2 weeks after being discharged from the hospital.

Discussion

In 1875, H Quincke reported the first case of traumatic chylothorax.⁷ Bessone et al⁸ classified chylothorax into four subclasses: congenital, iatrogenic, traumatic and non-traumatic with iatrogenic being the most common cause among all. Traumatic chylothorax, though uncommon, still affects a considerable proportion of the trauma cases which is 0.2%–3% after blunt thoracic trauma and 0.9%–1.9% after penetrating trauma.^{3 4} Therefore, traumatic chylothorax undoubtedly has been a subject of concern every now and then. Non-traumatic causes include intrinsic/extrinsic obstruction of the thoracic duct, liver cirrhosis, various malignancies, mediastinal lymphadenopathy or a sequela of tuberculosis.

Dulchavsky et al⁹ in 1988 reported 19 cases of chylothorax subsequent to blunt thoracic trauma. He proposed various mechanisms for the same being sudden flexion/hyperextension of the thoracic spine, shearing forces of the right diaphragmatic crus or fracture of the posterior ribs and/or vertebrae. In our case, probably chylothorax developed due to its rupture being associated with multiple posterior rib fractures. Milano et al¹⁰ stated that initially the leak may be confined to posterior mediastinum only and then 7–10 days later extended to either or both the pleural spaces. Studies report a time period of 2–7 days for clinical symptoms and signs to develop ensuing an injury with 7 days being the median interval of diagnosis.¹¹ The longest latency period reported until is 20 years.¹² However in our case, after a latency period of 4 days, bilateral chylothorax had already developed.

Chylothorax has a gradual onset and most common complaints being progressive dyspnoea and chest discomfort. As chyle is non-irritant to the pleura, pleuritic chest pain is seldom a complaint. Other clinical features include cough, hypovolemia, respiratory discomfort, malnutrition and immunosuppression.¹³ Therefore, it becomes mandatory to detect this condition early before the above-said fatal consequences develop. A high degree of clinical suspicion is needed to diagnose this rare condition. In a patient of blunt thoracic trauma, a chest X-ray is the usual first investigation. As chylothorax and pleural effusion or haemothorax are indistinguishable on a chest X-ray, chylothorax is invariably an incidental finding when on thoracocentesis or intercostal catheter drainage milky fluid is seen egressing the pleural cavity. Though uncommon, when chylothorax is preceded by blunt thoracic trauma, it is not surprising to find concomitant injuries namely posterior rib fractures and/or vertebral fractures.¹⁴ In our case, in addition to bilateral chylothorax both posterior rib fractures and first and second lumbar vertebral fractures were concurrently present. Quite often, haemothorax and chylothorax may coexist, thus obscuring the diagnosis of the latter.⁴ Table 1 shows the characteristics of chyle. The diagnosis of chylothorax is confirmatory only on biochemical analysis of the pleural fluid, particularly for triglycerides. Pleural effusions with triglyceride values estimated at more than 110 mg/dL have a 99% probability of being indicative of chylothorax. Values that are less than 50 mg/dL have a less than 5% probability of being indicative of chylothorax. For values between 50 and 110 mg/dL, the diagnosis is made by confirming the presence of chylomicrons.¹⁵ Our patient had triglyceride levels of 1200 mg/dL, thus leading to the diagnosis.

Table 1.

Characteristics of chyle

Colour	Milky white (can be serous)
Specific gravity	≥1.012
pH	7.4–7.8
Total protein	22–60 g/L
Total fat	4–60 g/L
Triglyceride	>100 mg/dL
Cholesterol-to-triglyceride ratio	<1
Electrophoresis	Chylomicrons
Electrolytes	Same as plasma levels
Fat-soluble vitamins	Present
Pancreatic exocrine enzymes	Present

Due to the rarity of the condition, there have not been many randomised controlled studies on the topic that would suggest a clearly defined management protocol for the condition. Various treatment modalities for chylothorax are shown in table 2. Thoracocentesis or intercostal catheter drainage is undertaken prior to anything else in order to evacuate chylous fluid, thus allowing adequate expansion of the lungs. Usually, the conservative approach is the first approach that is adopted, and it consists of keeping patient nill per oral and administering an MCT diet which not only optimises the deprived nutritional status of the patient but also decreases the thoracic duct flow as it is directly absorbed into the portal system. If required, TPN may be given in addition to the MCT diet which is reported to have improved the results observed in the conservative approach.¹⁶ Somatostatin or octreotide infusions have been used successfully to reduce intestinal chyle production and secondarily to reduce chyle leak. Somatostatin treatment is an important adjuvant in the conservative management of chyle leak.¹⁷ Success rates of up to 88% have been reported with conservative approach.⁶ In traumatic and congenital chylothoraces, the conservative approach results in resolution only in 50% of the cases.¹⁸ Our patient was also managed initially with TPN, MCT diet and subcutaneous octreotide administration.

Table 2.

Treatment options for chylothorax

Conservative treatment	Thoracocentesis. Intercostal drain insertion. Nill per mouth. Dietary measures. Medium-chain triglycerides. Fat-free diet/low-fat diet. Total parenteral nutrition. Somatostatin or octreotide administration
Surgical treatment	Thoracic duct ligation. At the leakage site. At supradiaphragmatic region. Pleurodesis. Talc. Fibrin glue. Tetracyclins. Pleurectomy. Pleuroperitoneal shunting. Peritoneal venous shunts.
Percutaneous thoracic duct embolisation
Radiotherapy
Chemotherapy

It is a matter of debate among various authors as when to shift the treatment from the nonoperative approach to operative means. Most authors prefer taking up the operative lines of treatment after having failed at 1–2 weeks of conservative treatment.^{1 19} In general, surgical intervention offers better results than conservative management when daily chyle leak exceeds 1 L/day for a period of more than 5 days or 1.5 L/day in an adult or >100 mL/kg body weight per day in a child, persistent chyle flow for more than 2 weeks, rapid decline in nutritional status despite conservative management.¹³ Our patient was operated after 10 days of conservative management as the chylous output remained more than 1 L/day. Prior to choosing the surgical modality, the site of a lymphatic leak can be identified by lymphangiography or by adding methylene blue dye to a fat source like olive oil or cream given enterally.⁴ Our patient also underwent preoperative lymphangiography; however, no site of the leak could be identified.

Surgical procedures for the management of chylothorax include thoracic duct ligation by thoracotomy or video-assisted thoracoscopy,^{4 6} pleurodesis, pleurectomy or pleuroperitoneal shunting. Ligation of the thoracic duct can be done either at the leakage site or in the supradiaphragmatic region where success rates of up to 90% have been reported in the latter.⁴ In our case, as the thoracic duct could not be identified intraoperatively, mass ligation of all the tissues between aorta, spine, oesophagus and pericardium was done in the supradiaphragmatic region via right-sided thoracotomy through sixth intercostal space. Alternatively, some authors report high success rates with talc pleurodesis for cases where thoracic duct could not be identified.¹⁸ Also, pleural decortications and surgical pleurodesis may be chosen to achieve the end result. With the adoption of surgical measures, the mortality rate of chylothorax has dropped down from 50% with conservative management to 10%.^{6 18}

With the advances in the medical sciences, newer treatment modalities are on the horizon. Radiotherapy and/or chemotherapy may be instituted for malignant chylothorax but results have not been very promising.¹⁸ Cope and Kaiser developed percutaneous TDE as a safe alternative to surgical intervention. Though success rates of up to 70% have been reported with TDE,^{20 21} it is technically demanding, requires high expertise and is not always successful.

Patient’s perspective.

I met with an accident while I was driving a car. It was a relief to know that I did not have any injuries when I went to a local hospital. It was on the third day after the accident that I started having difficulty in breathing on exertion. Some home remedies including steam inhalation had limited temporary effect and on the next day, I was out of my breath even at rest. I went to DMCH where I was admitted including a stay at ICU initially which made me worried in the beginning. I was first kept on medicines and later told that I needed surgery. Fearing the surgery, I was reluctant to undergo the same, but having no option left and properly counselled, I finally underwent surgery. However on the contrary to my worries, within days of surgery I felt significantly better and within about a week both the chest drains could be removed. I was soon discharged thereafter and a couple of weeks later I was able to comfortably carry out my daily routine activities. 2 months after the injury, I have not been on any medication and I feel perfectly healthy once again. Through many ups and downs, in the end, I am thankful to the whole hospital staff to have enabled me to live a healthy life again. In the end, I am happy that my case can be helpful to others who might share my fate of injuries.

Learning points.

• Though uncommon, bilateral chylothorax can still occur after blunt thoracic trauma. A high degree of clinical suspicion is required for early detection.

• Even a life-threatening condition such as massive bilateral chylothorax may not have any discernible feature on initial radiological imaging. Therefore, it is obligatory to keep chylothorax as one of the differentials in a patient experiencing dyspnoea within the first week of trauma. Also, a repeat chest X-ray on follow-up might prove helpful.

• Though conservative treatment forms the first line of management, if ineffective, the early surgical intervention, if undertaken, helps reduce the mortality and morbidity.

• Early diagnosis and timely intervention are keystone factors for a better outcome.