Patient Presentation A 9-month-old female came to clinic for her 9 month health supervision visit. She had a past medical history of transposition of the great arteries with intact septum and was status post arterial switch. She also had had chylothorax… Read on blog or Reader Pediatric Education Read on blog or Reader How Do You Treat Chylothorax? By Pediatric Education on July 1, 2024 Patient Presentation A 9-month-old female came to clinic for her 9 month health supervision visit. She had a past medical history of transposition of the great arteries with intact septum and was status post arterial switch. She also had had chylothorax after the surgery that had been treated with special formula and octreotide and the chylothorax had resolved. She was now taking standard formula. The pertinent physical exam showed a thin infant whose weight was 10% and increasing, and length and head circumference of 50%. She had a well-healed surgical scar. Heart showed normal rhythm and rate without murmur. Peripheral pulses were normal as was her lung examination. The rest of the examination was normal. The diagnosis of a low-weight patient after cardiac surgery and complications was made. She had not received influenza and COVID vaccines nor respiratory syncytial virus immunoglobulin so those were given. The patient had cardiac followup the following month, so additional weight monitoring by the primary care physician was not scheduled. Figure 139 - CXR AP obtained two weeks after surgery shows an extremely large right pleural effusion that upon thoracentesis was found to be chylous in nature. Median sternotomy sutures are seen along with mediastinal clips and staples. Discussion Even with the great efficiency of the cells and systems within the body, the movement of fluid between spaces isn't 100% efficient. Therefore excess fluid within the interstitial tissues of the body needs to be recaptured which is one of the main activities of the lymphatic system. Lymph, which in addition to water also contains cells, proteins, chylomicrons, particles, and sometimes bacteria, is moved from the interstitial spaces into a lymphatic system consisting of a fine network of ill-defined vessels with one-way valves that then moves the lymph into the lymph nodes. Lymph nodes then act as a filter, and the lymph is moved to the cisterna chyli. The cisterna chyli is located anteriorly to the great vessels near the lumbar vertebrae. The cisterna chyli becomes larger as it becomes the thoracic duct (TD) as it tracks superiorly and from right to left. The thoracic duct empties into the left internal jugular vein and left subclavian vein. The amount of lymph delivered is small at only 1.4 ml/hour but obviously is important. This equates to approximately 1 liter per month. When the lymphatic system and its vessels are obstructed, severed or overwhelmed with fluid, then lymphedema or lymph accumulations in the area occur. Large accumulations in potential body spaces can occur and in the abdomen are called chylous ascites or chyloperitoneum and in the pleural space are called chylothorax. Learning Point Chylothorax (CT) is one cause of pleural effusion. It can occur congenitally (1;10,000-24,000) or often because of trauma or surgery. Because of the TD's location, the TD is prone to damage during congenital heart and other thoracic surgery. Congenital CT is often due to congenital heart disease (15%), genetic abnormalities such as Down, Turner, and Noonan syndromes (15%), twin-to-twin transfusion (10%), viral infections (6%), and congenital anemia (5%). It accounts for ~5% of non-immune hydrops fetalis. In congenital CT the lymph circulation is impaired (due to obstruction, aplasia or hypoplasia) and fluid accumulates and eventually leaks into the pleural (and potentially other) space. The lymph accumulation can affect cardiac hemodynamics which also places additional strain on fluid management within the body exacerbating the problem. Lung tissue can also be hypoplastic because of the congenital CT. Diagnosis in the setting of trauma or post-operative surgery is expectant as this is a potential complication to be monitored for. Patients with respiratory and hemodynamic problems will be clinically examined and radiographically imaged which can identify the pleural effusion. In congenital CT infants are often diagnosed prenatally or soon after birth because of similar cardiopulmonary dysfunction. Evaluation of the fluid via pleural tap can identify its chylous nature and distinguish it from other types of pleural effusions. If a baby has been fed, then milky fluid is often seen because of excessive fat within the fluid. Non-milky, but chylous effusion is distinguished by triglycerides "...1.2 mmol/L or 200 mg/dL and more than 1000 cells/mL with a predominance of lymphocytes, protein levels above 2.5 g/dL, and lactate dehydrogenates above 110 IU/L...." Treatment of congenital CT for fetuses includes maternal diet changes and surgical procedures to shunt pleural fluid or to remove the space (i.e. pleurodesis). For neonates and CT due to trauma or surgery, close monitoring works for many infants that are cardiopulmonarily stable as spontaneous leak closure can occur. Other treatment includes nutritional management with low-fat medium chain triglyceride formula (note medium chain fatty acids are absorbed directly into the portal venous circulation) which can decrease the lymph flow and assist in spontaneous closure. Some infants may need total parenteral nutrition though. Octreotide and similar medications reduce lymph flow and can be used. Surgical treatment can include thoracentesis, chest tube drainage, TD embolization, surgical ligation, shunting and pleurodesis. Questions for Further Discussion 1. What are potential complication of cardiovascular surgery? A review can be found here. 2. What are potential complications of pneumonia? A review can be found here. 3. What are causes of ascites? A review can be found here. 4. What are the major acyanotic congenital heart diseases? A review can be found here. 5. What are the major cyanotic congenital heart diseases? A review can be found here. Related Cases Disease: Chylothorax | Pleural Diseases | Lymphatic Diseases | Congenital Heart Disease Symptom/Presentation: Health Maintenance and Disease Prevention Specialty: Cardiology / Cardiovascular-Thoracic Surgery | Neonatology | General Pediatrics Age: Infant To Learn More To view pediatric review articles on this topic from the past year check PubMed. Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews. Information prescriptions for patients can be found at MedlinePlus for these topics: Pleural Disorders and Lymphatic Diseases To view current news articles on this topic check Google News. To view images related to this topic check Google Images. To view videos related to this topic check YouTube Videos. Lopez-Gutierrez JC, Tovar JA. Chylothorax and chylous ascites: Management and pitfalls. Seminars in Pediatric Surgery. 2014;23(5):298-302. doi:10.1053/j.sempedsurg.2014.09.011 Rocha G, Arnet V, Soares P, et al. Chylothorax in the neonate - A stepwise approach algorithm. Pediatric Pulmonology. 2021;56(10):3093-3105. doi:10.1002/ppul.25601 Samanidis G, Kourelis G, Bounta S, Kanakis M. Postoperative Chylothorax in Neonates and Infants after Congenital Heart Disease Surgery - Current Aspects in Diagnosis and Treatment. Nutrients. 2022;14(9):1803. doi:10.3390/nu14091803 Ilahi M, St Lucia K, Ilahi TB. Anatomy, Thorax, Thoracic Duct. In: StatPearls. StatPearls Publishing; 2024. Accessed April 16, 2024. http://www.ncbi.nlm.nih.gov/books/NBK513227/ Author Donna M. D'Alessandro, MD Professor of Pediatrics, University of Iowa

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