Chylothorax: Difference between revisions
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A '''chylothorax''' is an abnormal accumulation of [[chyle]], a type of [[lipid]]-rich [[lymph]], in the [[pleural space|space surrounding the lung]]. |
A '''chylothorax''' is an abnormal accumulation of [[chyle]], a type of [[lipid]]-rich [[lymph]], in the [[pleural space|space surrounding the lung]]. The [[lymphatic]]s of the [[digestive system]] normally returns lipids absorbed from the [[small bowel]] via the [[thoracic duct]], which ascends behind the [[esophagus]] to drain into the [[left brachiocephalic vein]]. If disruption of normal thoracic duct drainage occurs, either due to obstruction or rupture, chyle can leak and accumulate within the negative-pressured pleural space. In people on a normal diet, this fluid collection can have a turbid, milky white appearance, since chyle contains [[emulsified]] [[triglyceride]]s. |
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Chylothorax is a rare but serious condition, as it signals leakage of the thoracic duct or one of its tributaries. There are many treatments, both surgical and conservative.<ref name="Mohan_2018" /> About 2–3% of all fluid collections surrounding the lungs (pleural effusions) are chylothoraces.<ref>{{Cite web|url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/chylothorax-and-cholesterol-effusion/|title=Chylothorax and Cholesterol Effusion|date=2019-01-23|website=Pulmonology Advisor|language=en-US|access-date=2019-03-24}}</ref> It is important to distinguish a chylothorax from a pseudochylothorax (a [[pleural effusion]] that happens to be high in [[cholesterol]]), which has a similar appearance visually but |
Chylothorax is a rare but serious condition, as it signals leakage of the thoracic duct or one of its tributaries. There are many treatments, both surgical and conservative.<ref name="Mohan_2018" /> About 2–3% of all fluid collections surrounding the lungs (pleural effusions) are chylothoraces.<ref>{{Cite web|url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/chylothorax-and-cholesterol-effusion/|title=Chylothorax and Cholesterol Effusion|date=2019-01-23|website=Pulmonology Advisor|language=en-US|access-date=2019-03-24}}</ref> It is important to distinguish a chylothorax from a pseudochylothorax (a [[pleural effusion]] that happens to be high in [[cholesterol]]), which has a similar appearance visually but results from more chronic [[inflammation|inflammatory processes]] and requires a different treatment.<ref>{{cite web |title=Clinical presentation, diagnosis and management of cholesterol effusions |first=John |last=Heffner | name-list-style = vanc |url= http://www.uptodate.com/contents/clinical-presentation-diagnosis-and-management-of-cholesterol-effusions?source=see_link |publisher=UpToDate |version=8.0 |access-date=30 October 2014 }}</ref> |
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== Signs and symptoms == |
== Signs and symptoms == |
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The symptoms of a chylothorax depend its size and the underlying cause. A small chylothorax may not cause any symptoms and only be detected on a [[chest X-ray]] performed for another reason. A large chylothorax may lead to breathlessness or a feeling of pressure in the chest, caused by fluid restricting the expansion of the lungs |
The symptoms of a chylothorax depend its size and the underlying cause. A small chylothorax may not cause any symptoms and only be detected on a [[chest X-ray]] performed for another reason. A large chylothorax may lead to breathlessness or a feeling of pressure in the chest, caused by fluid restricting the expansion of the lungs; however, large chylothoraces may remain asymptomatic if the chylothorax has accumulated slowly, as the lungs may become used to the pressure over time. Fever or chest pain usually do not result from chylothorax, as chyle does not generate inflammation by itself.<ref>{{Cite journal|last1=Schild|first1=Hans H|last2=Strassburg|first2=Christian P|last3=Welz|first3=Armin|last4=Kalff|first4=Jörg|date=2013–2014|title=Treatment Options in Patients With Chylothorax|journal=Deutsches Ärzteblatt International|volume=110|issue=48|pages=819–826|doi=10.3238/arztebl.2013.0819|issn=1866-0452|pmc=3865492|pmid=24333368}}</ref> |
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On examination, chylothorax may lead to reduced breath sounds on the affected side, associated with a dull sound when the chest is tapped or percussed. In cases of postoperative chylothorax, the first sign may be persistent drainage from intercostal drains.<ref name="Mohan_2018" /> |
On examination, chylothorax may lead to reduced breath sounds on the affected side, associated with a dull sound when the chest is tapped or percussed. In cases of postoperative chylothorax, the first sign may be persistent drainage from intercostal drains.<ref name="Mohan_2018" /> Large chylothoraces may cause signs related to the loss of nutrients, including features of malnutrition or decreased ability to fight infections.<ref name="Nair_2007">{{cite journal|vauthors=Nair SK, Petko M, Hayward MP|date=2007|title=Aetiology and management of chylothorax in adults|journal=European Journal of Cardio-Thoracic Surgery|volume=32|issue=2|pages=362–9|doi=10.1016/j.ejcts.2007.04.024|pmid=17580118|doi-access=free}}</ref> Rapidly accumulating chylothoraces can cause a sudden drop in blood volume, leading to low blood pressure.<ref name="Nair_2007" /> |
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==Causes== |
==Causes== |
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Three main types of chylothorax exist: traumatic, non-traumatic, and idiopathic. Historically the most common form of chylothorax was non-traumatic, but traumatic chylothoraces now represent the majority of cases, with most arising as postoperative complications of surgery.<ref name="Martucci2015"/><ref name="Pillay2016">{{cite journal |last1=Pillay |first1=TG |last2=Singh |first2=B |title=A review of traumatic chylothorax |journal=Injury |date=March 2016 |volume=47 |issue=3 |pages=545–50 |doi=10.1016/j.injury.2015.12.015 |pmid=26776461}}</ref> Most often, non-traumatic chylothoraces result from cancer.<ref name= "Mohan_2018">{{cite book |last1= Rudrappa |first1=Mohan |last2=Paul |first2=Manju | name-list-style = vanc |chapter=Chylothorax |date=2018 |chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK459206/ |title =StatPearls | location = Treasure Island (FL) |publisher= StatPearls Publishing |pmid=29083798 |access-date=2019-03-05 }}</ref> Chylothoraces can also be classified as low- or high-output based on the rate of chyle accumulation: low-output chylothoraces accumulate <500 mL of chyle per 24 hours, while high-output chylothoraces accumulate >1000 mL per 24 hours.<ref name="Lyon2013">{{cite journal |last1=Lyon |first1=S |last2=Mott |first2=N |last3=Koukounaras |first3=J |last4=Shoobridge |first4=J |last5=Hudson |first5=PV |title=Role of interventional radiology in the management of chylothorax: a review of the current management of high output chylothorax |journal=CardioVascular and Interventional Radiology |date=June 2013 |volume=36 |issue=3 |pages=599–607 |doi=10.1007/s00270-013-0605-3 |pmid=23580112|s2cid=22158968 }}</ref> |
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=== Non-traumatic === |
=== Non-traumatic === |
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Non-traumatic chylothorax typically occurs due to cancers: [[chronic lymphocytic leukemia]], [[lung cancer]], [[lymphoma]], [[Kaposi sarcoma]], metastatic [[carcinoma]] or [[esophageal cancer]] can potentially cause chylothorax. Infectious causes have also occured, most often in developing countries. Most often, chylothorax complicates [[tuberculous lymphadenitis]]. Other possible causative infections include [[aortitis]], [[histoplasmosis]], and [[filariasis]]. Chylothorax can also occur congenitally, and may co-occur with other lymphatic malformations like [[Lymphangiectasia|lymphangiectasis]] and [[lymphangiomatosis]]. Other congenital conditions like [[tuberous sclerosis]], congenital heart disease, [[Down syndrome|trisomy 21 (Down syndrome)]], [[Noonan syndrome]], or [[Turner syndrome]] (missing X chromosome) can also cause congenital chylothorax. Other, more rare causes of congenital chylothorax include [[Castleman's disease]], [[yellow nail syndrome]], [[Waldenström's macroglobulinemia]], [[sarcoidosis]], [[venous thrombosis]], [[Radiation therapy|thoracic radiation]], [[macroglobulinemia]], [[amyloidosis]], and a [[Goitre|goiter]]. These diseases cause chylothorax by obstructing or destroying the thoracic duct. Also, [[parenteral nutrition]] has caused it; a quick dose of total parenteral nutrition can overwhelm the thoracic duct, causing the chyle to leak into the surrounding pleural space.<ref name="Mohan_2018" /> |
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=== Traumatic === |
=== Traumatic === |
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[[iatrogenesis|Iatrogenic]] chylothorax |
[[iatrogenesis|Iatrogenic]] chylothorax complicating surgery represents the most common variety of chylothorax.<ref name="Mohan_2018" /> It occurs as a common and serious complication of a [[pneumonectomy]];<ref>{{Cite journal|last1=Vallières|first1=E.|last2=Karmy-Jones|first2=R.|last3=Wood|first3=D. E.|date=1999|title=Early complications. Chylothorax|journal=Chest Surgery Clinics of North America|volume=9|issue=3|pages=609–616, ix|issn=1052-3359|pmid=10459431}}</ref> in particular, it frequently complicates surgeries requiring mediastinal dissection.<ref name="Nair_2007" /> The probability of chylothorax depends on the type of surgery. An [[esophagostomy]] carries the greatest risk of chylothorax, with a 5-10% risk. Lung resection and mediastinal node dissection have the second highest risk, with 3-7% risk. Other operations like [[mediastinal tumor]] resection, thoracic aneurysm repair, sympathectomy, and any other surgeries taking place in the lower neck or [[mediastinum]] can lead to chylothorax. Chylotharax after non-surgical trauma has also occurred after central line placement, [[Pacemaker|pacemaker implantation]], and embolization of a pulmonary [[arteriovenous malformation]]. [[Blunt trauma]] to the chest region can also cause chylothorax, which has occurred after [[Blast injury|blast injuries]] and even simple injuries from coughing or sneezing.<ref name="Mohan_2018" /> |
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== Mechanism == |
== Mechanism == |
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Whether a chylothorax occurs in the left or right pleural space is a consequence of the thoracic duct's anatomic location in the body and depends on the level where the duct was injured. If the thoracic duct is injured above the fifth [[thoracic vertebra]], then a left-sided chylothorax results.<ref name="Nair_2007" /> Conversely, a thoracic duct injury below that level will lead to the formation of a right-sided chylothorax.<ref name="Nair_2007" /> Chylothoraces most commonly occur in the right pleural space (50% of cases).<ref name="Nair_2007" /> Left-sided and bilateral chylothoraces are less common and occur in 33% and 17% of cases, respectively.<ref name="Nair_2007" /> |
Whether a chylothorax occurs in the left or right pleural space is a consequence of the thoracic duct's anatomic location in the body and depends on the level where the duct was injured. If the thoracic duct is injured above the fifth [[thoracic vertebra]], then a left-sided chylothorax results.<ref name="Nair_2007" /> Conversely, a thoracic duct injury below that level will lead to the formation of a right-sided chylothorax.<ref name="Nair_2007" /> Chylothoraces most commonly occur in the right pleural space (50% of cases).<ref name="Nair_2007" /> Left-sided and bilateral chylothoraces are less common and occur in 33% and 17% of cases, respectively.<ref name="Nair_2007" /> |
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In the case of cancer, invasion into the thoracic duct or collateral lymph channels can obstruct lymph. In the case of [[mediastinal lymphadenopathy]], the enlarged lymph node causes compression of the lymphatic channels and thoracic duct. This impedes the centripetal drainage of the flow of lymph from the edges of the lung parenchyma and pleural surfaces. This causes the chyle to ooze extensively into the pleural cavity, leading to a chylothorax. In the case of [[yellow nail syndrome]], or lymphedema, chylothorax is caused by hypoplasia or dilation of the lymph vessels. In rare cases, |
In the case of cancer, invasion into the thoracic duct or collateral lymph channels can obstruct lymph. In the case of [[mediastinal lymphadenopathy]], the enlarged lymph node causes compression of the lymphatic channels and thoracic duct. This impedes the centripetal drainage of the flow of lymph from the edges of the lung parenchyma and pleural surfaces. This causes the chyle to ooze extensively into the pleural cavity, leading to a chylothorax. In the case of [[yellow nail syndrome]], or lymphedema, chylothorax is caused by hypoplasia or dilation of the lymph vessels. In rare cases, such as hepatic chylothorax, fluid from chylous [[ascites]] crosses the diaphragm into the pleural cavity. Idiopathic cases, such as genetic disorders have an unknown mechanism.<ref name="Nair_2007" /> Up to three liters of chyle can easily drain into the pleural space daily.<ref name=":1" /> |
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== Diagnosis == |
== Diagnosis == |
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Chest X-rays can detect a chylothorax. It appears as a dense, homogeneous area that obscures the costophrenic and cardiophrenic angles. Ultrasounds can also detect a chylothorax, which appears as an echoic region that is isodense with no septation or loculation. However, neither a normal chest x-ray nor an ultrasound can differentiate a chylothorax from any other type of pleural effusion.<ref name="Mohan_2018" /> |
Chest X-rays can detect a chylothorax. It appears as a dense, homogeneous area that obscures the costophrenic and cardiophrenic angles. Ultrasounds can also detect a chylothorax, which appears as an echoic region that is isodense with no septation or loculation. However, neither a normal chest x-ray nor an ultrasound can differentiate a chylothorax from any other type of pleural effusion.<ref name="Mohan_2018" /> |
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[[File:Chest X-ray showing bilateral chylothorax.png|thumb|Chest X-ray showing bilateral chylothorax]] |
[[File:Chest X-ray showing bilateral chylothorax.png|thumb|Chest X-ray showing bilateral chylothorax]] |
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A thoracic MRI can find the [[cisterna chyli]], making it possible to confirm chylothorax; despite this, MRI does not work ideally scan the chest, making usage rare. Another diagnostic technique is conventional [[lymphangiography]]; however, methods equally sensitive yet less invasive, making usage rare. Lymphangiography procedures involve injecting the contrast dye agent [[lipiodol]] into the lymphatic vessels. When that fluid enters the pleural cavity, images identify the chylothorax and the source of any leak in the thoracic duct.<ref name="Mohan_2018" /> |
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Another, more commonly used type of lymphogram is [[nuclear lymphoscintigraphy]]; this procedure |
Another, more commonly used type of lymphogram is [[nuclear lymphoscintigraphy]]; this procedure involves injecting human [[pentetic acid]] labeled Tc99minto the subcutaneous lesions of both sides of the dorsum of the foot. Then two images, anterior and posterior, are obtained using gamma-ray cameras. This test can be used with an integrated low-dose CT-scan with photon emission to get images that are more precise. Once pleural effusion is detected, a [[thoracentesis]] is recommended.<ref name="Mohan_2018" /> |
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The fluid of a chylothorax may appear milky, serous or serosanguineous |
The fluid of a chylothorax may appear milky, serous or serosanguineous; however, a non-milky appearance does not exclude a chylothorax from consideration. Due to the high triglyceride content in chyle, high [[triglyceride]] presence in the effusion (>110 mg/dL) confirms the presence of a chylothorax; in addition, a pleural effusion low in triglyceride (<50 mg/dL) virtually excludes the diagnosis.<ref name="Skouras2010">{{cite journal |last1=Skouras |first1=V |last2=Kalomenidis |first2=I |title=Chylothorax: diagnostic approach |journal=Current Opinion in Pulmonary Medicine |date=July 2010 |volume=16 |issue=4 |pages=387–93 |doi=10.1097/MCP.0b013e328338dde2 |pmid=20410823|s2cid=26096783 }}</ref><ref name="Nadolski2016">{{cite journal |last1=Nadolski |first1=G |title=Nontraumatic Chylothorax: Diagnostic Algorithm and Treatment Options |journal=Techniques in Vascular and Interventional Radiology |date=December 2016 |volume=19 |issue=4 |pages=286–90 |doi=10.1053/j.tvir.2016.10.008 |pmid=27993324}}</ref> Pleural effusions containing triglycerides between 50 and 110 mg/dL, indicate further analysis of the [[lipoprotein]] content of the pleural effusion to evaluate for [[chylomicron]]s: presence of chylomicrons confirms the condition.<ref name="Skouras2010"/> Chylothoraces are typically exudative and often contain a high number of [[lymphocyte]]s and have low levels of the [[enzyme]] [[lactate dehydrogenase]] (LDH). However, atypical chylothoraces can occur and are transudative in 14% of cases. A milky appearance of pleural fluid alone cannot confirm the diagnosis of chylothorax as pseudochylothoraces and [[empyema]]s can mimic this appearance; conversely, the absence of a milky appearance does not mean a chylothorax is not present as they may instead appear serous or bloody.<ref name="Skouras2010"/><ref name="Skouras2010"/> |
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==Treatment== |
==Treatment== |
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=== Horses === |
=== Horses === |
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Chylothorax |
Chylothorax occurs uncommonly in horses. Clinical signs and symptoms in foals include difficulty breathing, fast breathing, cough, fever, and lethargy. The fluid generally appears opalescent and milky without any odor. A line of fluid is observed on percussion and there are reduced lung sounds. To differentiate between chyle is pseudochyle, which does not clear after [[centrifugation]]. Limited information exists on the treatment of chylothorax in horses. Supportive care, antimicrobials, drainage of the thorax, and dietary management have had success. Surgery has in other animals has had limited success; however, no reports exist in horses. Although successes have occurred, the lack of data makes the prognosis relatively unknown.<ref>{{Cite book|last1=Weese|first1=Scott|url=https://books.google.com/books?id=Cu-XUjVS85QC|title=Equine Clinical Medicine, Surgery and Reproduction|last2=Munroe|first2=Dr Graham|last3=Munroe|first3=Graham|date=2011-03-15|publisher=CRC Press|isbn=978-1-84076-608-0|location=|page=476|language=en}}</ref> |
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== References == |
== References == |
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Revision as of 02:03, 4 May 2023
| Chylothorax | |
|---|---|
 | |
| Three bottles of chyle drained from a chylothorax | |
| Specialty | Respiratory medicine |
| Symptoms | None, breathlessness |
| Complications | Dehydration, malnutrition, abnormal electrolyte levels, weakened immune system |
| Types | Low output, high output |
| Causes | Complication of surgery, trauma, cancer, infections, lymph vessel abnormalities |
| Diagnostic method | X-ray, CT scan, thoracic MRI, fluid sampling |
| Treatment | Removing fat from the diet, decreasing lymph flow, chest tube, surgery |
| Medication | Octreotide, midodrine, and sirolimus |
| Prognosis | ~10% risk of death |
A chylothorax is an abnormal accumulation of chyle, a type of lipid-rich lymph, in the space surrounding the lung. The lymphatics of the digestive system normally returns lipids absorbed from the small bowel via the thoracic duct, which ascends behind the esophagus to drain into the left brachiocephalic vein. If disruption of normal thoracic duct drainage occurs, either due to obstruction or rupture, chyle can leak and accumulate within the negative-pressured pleural space. In people on a normal diet, this fluid collection can have a turbid, milky white appearance, since chyle contains emulsified triglycerides.
Chylothorax is a rare but serious condition, as it signals leakage of the thoracic duct or one of its tributaries. There are many treatments, both surgical and conservative.[1] About 2–3% of all fluid collections surrounding the lungs (pleural effusions) are chylothoraces.[2] It is important to distinguish a chylothorax from a pseudochylothorax (a pleural effusion that happens to be high in cholesterol), which has a similar appearance visually but results from more chronic inflammatory processes and requires a different treatment.[3]
Signs and symptoms
The symptoms of a chylothorax depend its size and the underlying cause. A small chylothorax may not cause any symptoms and only be detected on a chest X-ray performed for another reason. A large chylothorax may lead to breathlessness or a feeling of pressure in the chest, caused by fluid restricting the expansion of the lungs; however, large chylothoraces may remain asymptomatic if the chylothorax has accumulated slowly, as the lungs may become used to the pressure over time. Fever or chest pain usually do not result from chylothorax, as chyle does not generate inflammation by itself.[4]
On examination, chylothorax may lead to reduced breath sounds on the affected side, associated with a dull sound when the chest is tapped or percussed. In cases of postoperative chylothorax, the first sign may be persistent drainage from intercostal drains.[1] Large chylothoraces may cause signs related to the loss of nutrients, including features of malnutrition or decreased ability to fight infections.[5] Rapidly accumulating chylothoraces can cause a sudden drop in blood volume, leading to low blood pressure.[5]
Causes
Three main types of chylothorax exist: traumatic, non-traumatic, and idiopathic. Historically the most common form of chylothorax was non-traumatic, but traumatic chylothoraces now represent the majority of cases, with most arising as postoperative complications of surgery.[6][7] Most often, non-traumatic chylothoraces result from cancer.[1] Chylothoraces can also be classified as low- or high-output based on the rate of chyle accumulation: low-output chylothoraces accumulate <500 mL of chyle per 24 hours, while high-output chylothoraces accumulate >1000 mL per 24 hours.[8]
Non-traumatic
Non-traumatic chylothorax typically occurs due to cancers: chronic lymphocytic leukemia, lung cancer, lymphoma, Kaposi sarcoma, metastatic carcinoma or esophageal cancer can potentially cause chylothorax. Infectious causes have also occured, most often in developing countries. Most often, chylothorax complicates tuberculous lymphadenitis. Other possible causative infections include aortitis, histoplasmosis, and filariasis. Chylothorax can also occur congenitally, and may co-occur with other lymphatic malformations like lymphangiectasis and lymphangiomatosis. Other congenital conditions like tuberous sclerosis, congenital heart disease, trisomy 21 (Down syndrome), Noonan syndrome, or Turner syndrome (missing X chromosome) can also cause congenital chylothorax. Other, more rare causes of congenital chylothorax include Castleman's disease, yellow nail syndrome, Waldenström's macroglobulinemia, sarcoidosis, venous thrombosis, thoracic radiation, macroglobulinemia, amyloidosis, and a goiter. These diseases cause chylothorax by obstructing or destroying the thoracic duct. Also, parenteral nutrition has caused it; a quick dose of total parenteral nutrition can overwhelm the thoracic duct, causing the chyle to leak into the surrounding pleural space.[1]
Traumatic
Iatrogenic chylothorax complicating surgery represents the most common variety of chylothorax.[1] It occurs as a common and serious complication of a pneumonectomy;[9] in particular, it frequently complicates surgeries requiring mediastinal dissection.[5] The probability of chylothorax depends on the type of surgery. An esophagostomy carries the greatest risk of chylothorax, with a 5-10% risk. Lung resection and mediastinal node dissection have the second highest risk, with 3-7% risk. Other operations like mediastinal tumor resection, thoracic aneurysm repair, sympathectomy, and any other surgeries taking place in the lower neck or mediastinum can lead to chylothorax. Chylotharax after non-surgical trauma has also occurred after central line placement, pacemaker implantation, and embolization of a pulmonary arteriovenous malformation. Blunt trauma to the chest region can also cause chylothorax, which has occurred after blast injuries and even simple injuries from coughing or sneezing.[1]
Mechanism
The main mechanism of chylothorax is the leaking of chyle from the thoracic duct, usually caused by a disturbance affecting the structural integrity of the thoracic duct.[5] For example, placement of a central venous catheter can potentially disrupt drainage of lymph into the subclavian veins, followed by the thoracic duct, resulting in chylothorax.[5] The disturbances cause the pressure in the thoracic duct to increase. Soon, collateral channels form, which eventually drain into the thorax.[10] Trauma affecting the thoracic duct is the most common disturbing mechanism.
Whether a chylothorax occurs in the left or right pleural space is a consequence of the thoracic duct's anatomic location in the body and depends on the level where the duct was injured. If the thoracic duct is injured above the fifth thoracic vertebra, then a left-sided chylothorax results.[5] Conversely, a thoracic duct injury below that level will lead to the formation of a right-sided chylothorax.[5] Chylothoraces most commonly occur in the right pleural space (50% of cases).[5] Left-sided and bilateral chylothoraces are less common and occur in 33% and 17% of cases, respectively.[5]
In the case of cancer, invasion into the thoracic duct or collateral lymph channels can obstruct lymph. In the case of mediastinal lymphadenopathy, the enlarged lymph node causes compression of the lymphatic channels and thoracic duct. This impedes the centripetal drainage of the flow of lymph from the edges of the lung parenchyma and pleural surfaces. This causes the chyle to ooze extensively into the pleural cavity, leading to a chylothorax. In the case of yellow nail syndrome, or lymphedema, chylothorax is caused by hypoplasia or dilation of the lymph vessels. In rare cases, such as hepatic chylothorax, fluid from chylous ascites crosses the diaphragm into the pleural cavity. Idiopathic cases, such as genetic disorders have an unknown mechanism.[5] Up to three liters of chyle can easily drain into the pleural space daily.[10]
Diagnosis
Chest X-rays can detect a chylothorax. It appears as a dense, homogeneous area that obscures the costophrenic and cardiophrenic angles. Ultrasounds can also detect a chylothorax, which appears as an echoic region that is isodense with no septation or loculation. However, neither a normal chest x-ray nor an ultrasound can differentiate a chylothorax from any other type of pleural effusion.[1]
A thoracic MRI can find the cisterna chyli, making it possible to confirm chylothorax; despite this, MRI does not work ideally scan the chest, making usage rare. Another diagnostic technique is conventional lymphangiography; however, methods equally sensitive yet less invasive, making usage rare. Lymphangiography procedures involve injecting the contrast dye agent lipiodol into the lymphatic vessels. When that fluid enters the pleural cavity, images identify the chylothorax and the source of any leak in the thoracic duct.[1]
Another, more commonly used type of lymphogram is nuclear lymphoscintigraphy; this procedure involves injecting human pentetic acid labeled Tc99minto the subcutaneous lesions of both sides of the dorsum of the foot. Then two images, anterior and posterior, are obtained using gamma-ray cameras. This test can be used with an integrated low-dose CT-scan with photon emission to get images that are more precise. Once pleural effusion is detected, a thoracentesis is recommended.[1]
The fluid of a chylothorax may appear milky, serous or serosanguineous; however, a non-milky appearance does not exclude a chylothorax from consideration. Due to the high triglyceride content in chyle, high triglyceride presence in the effusion (>110 mg/dL) confirms the presence of a chylothorax; in addition, a pleural effusion low in triglyceride (<50 mg/dL) virtually excludes the diagnosis.[11][12] Pleural effusions containing triglycerides between 50 and 110 mg/dL, indicate further analysis of the lipoprotein content of the pleural effusion to evaluate for chylomicrons: presence of chylomicrons confirms the condition.[11] Chylothoraces are typically exudative and often contain a high number of lymphocytes and have low levels of the enzyme lactate dehydrogenase (LDH). However, atypical chylothoraces can occur and are transudative in 14% of cases. A milky appearance of pleural fluid alone cannot confirm the diagnosis of chylothorax as pseudochylothoraces and empyemas can mimic this appearance; conversely, the absence of a milky appearance does not mean a chylothorax is not present as they may instead appear serous or bloody.[11][11]
Treatment
The treatment for chylothorax depends on the underlying cause but may include dietary modification, medication to prevent chyle formation including somatostatin/octreotide, midodrine and sirolimus, pleurodesis, and surgical treatment including ligation of the thoracic duct, pleurovenous or pleuroperitoneal shunting or thoracic duct embolization.[1]
Initial
The initial treatment of a chylothorax is usually drainage of the fluid from the pleural space. This may be necessary to restore lung function compromised by the pressure exerted by the chyle on the lungs.[1] Those with large chylothoraces may need nutritional support due to the nutrients lost, primarily to correct protein and electrolyte losses. Once the affected person is hemodynamically and nutritionally stable, then specific treatment can begin.[5]
Conservative
A conservative treatment is changing diet to include fewer long-chain fatty acids, in particular free fatty acids. Since chyle is formed from these acids, chyle formation will reduce, allowing the defects to heal spontaneously. However, this can lead to fat deficiency and malnutrition over time. A possible response to this drawback is a venous fat hemorrhage, in which small and medium-chain fatty acids are given by diet, and long-chain fatty acids are given intravenously. Thoracentesis and an indwelling catheter for use at home is generally used to drain the chylothorax.[1] If a malignant neoplastic chylothorax is present, then treatment with radiotherapy and/or chemotherapy is warranted.
Surgical
Surgery is indicated if the case is post-traumatic, iatrogenic, or refractory to other treatments, in which cases surgery reduces mortality by 40%. One invasive surgical intervention called a thoracic duct ligation involves closing off the thoracic ducts.[1] Surgical pleurodesis is another option and can be undertaken if the affected person fails to respond to conservative treatment and is not a candidate for surgical intervention.[13]
Another treatment option is pleuroperitoneal shunting (creating a communication channel between the pleural space and peritoneal cavity). Since surgery to close the leak is not reliable, talc pleurodesis is recommended; in a case study of 19 people with refractory malignant chylothorax due to lymphoma, it resulted in success for all affected individuals.[5] Chemical pleurodesis is an option, since the leaking of lymphatic fluids is stopped by irritating the lungs and chest wall, resulting in a sterile inflammation. This causes the lung and the chest wall to fuse together, thus preventing lymphatic fluids from leaking into the pleural space.[14]
Prognosis
The morbidity and mortality rates associated with chylothorax have declined as treatments have improved. Malignant, bilateral, and chronic chylothoraces have an inferior prognosis to other types.[5] Currently, the mortality and morbidity rates are about 10% if treated surgically.[1] If cases are post-operative and treated conservatively, mortality rates approach 50%.[5]
Complications
Complications of chylothorax include malnutrition, immunosuppression, dehydration, and respiratory distress.[6] The severity of the complications depends on how quickly the chylothorax accumulated, its size, and its chronicity.[13]
Epidemiology
Chylothoraces are rare and usually occur as a complication of surgeries in the neck and mediastinum. It has no gender or age predisposition. A chylothorax occurs in 0.2-1% of cardiothoracic surgeries, 5-10% of esophagostomies, and 3-7% of lung resections.[1]
Other animals
Horses
Chylothorax occurs uncommonly in horses. Clinical signs and symptoms in foals include difficulty breathing, fast breathing, cough, fever, and lethargy. The fluid generally appears opalescent and milky without any odor. A line of fluid is observed on percussion and there are reduced lung sounds. To differentiate between chyle is pseudochyle, which does not clear after centrifugation. Limited information exists on the treatment of chylothorax in horses. Supportive care, antimicrobials, drainage of the thorax, and dietary management have had success. Surgery has in other animals has had limited success; however, no reports exist in horses. Although successes have occurred, the lack of data makes the prognosis relatively unknown.[15]
References
- ^ a b c d e f g h i j k l m n o Rudrappa M, Paul M (2018). "Chylothorax". StatPearls. Treasure Island (FL): StatPearls Publishing. PMID 29083798. Retrieved 2019-03-05.
- ^ "Chylothorax and Cholesterol Effusion". Pulmonology Advisor. 2019-01-23. Retrieved 2019-03-24.
- ^ Heffner J. "Clinical presentation, diagnosis and management of cholesterol effusions". 8.0. UpToDate. Retrieved 30 October 2014.
- ^ Schild, Hans H; Strassburg, Christian P; Welz, Armin; Kalff, Jörg (2013–2014). "Treatment Options in Patients With Chylothorax". Deutsches Ärzteblatt International. 110 (48): 819–826. doi:10.3238/arztebl.2013.0819. ISSN 1866-0452. PMC 3865492. PMID 24333368.
- ^ a b c d e f g h i j k l m n Nair SK, Petko M, Hayward MP (2007). "Aetiology and management of chylothorax in adults". European Journal of Cardio-Thoracic Surgery. 32 (2): 362–9. doi:10.1016/j.ejcts.2007.04.024. PMID 17580118.
- ^ a b Martucci, N; Tracey, M; Rocco, G (November 2015). "Postoperative Chylothorax". Thoracic Surgery Clinics. 25 (4): 523–8. doi:10.1016/j.thorsurg.2015.07.014. PMID 26515952.
- ^ Pillay, TG; Singh, B (March 2016). "A review of traumatic chylothorax". Injury. 47 (3): 545–50. doi:10.1016/j.injury.2015.12.015. PMID 26776461.
- ^ Lyon, S; Mott, N; Koukounaras, J; Shoobridge, J; Hudson, PV (June 2013). "Role of interventional radiology in the management of chylothorax: a review of the current management of high output chylothorax". CardioVascular and Interventional Radiology. 36 (3): 599–607. doi:10.1007/s00270-013-0605-3. PMID 23580112. S2CID 22158968.
- ^ Vallières, E.; Karmy-Jones, R.; Wood, D. E. (1999). "Early complications. Chylothorax". Chest Surgery Clinics of North America. 9 (3): 609–616, ix. ISSN 1052-3359. PMID 10459431.
- ^ a b Talwar, Arunbh, and Hans J Lee. “A Contemporary Review of Chylothorax.” A Contemporary Review of Chylothorax, 2007, medind.nic.in/iae/t08/i4/iaet08i4p343.pdf.
- ^ a b c d Skouras, V; Kalomenidis, I (July 2010). "Chylothorax: diagnostic approach". Current Opinion in Pulmonary Medicine. 16 (4): 387–93. doi:10.1097/MCP.0b013e328338dde2. PMID 20410823. S2CID 26096783.
- ^ Nadolski, G (December 2016). "Nontraumatic Chylothorax: Diagnostic Algorithm and Treatment Options". Techniques in Vascular and Interventional Radiology. 19 (4): 286–90. doi:10.1053/j.tvir.2016.10.008. PMID 27993324.
- ^ a b Kumar, Abhishek; Harris, Kassem; Roche, Charles; Dhillon, Samjot Singh (2014-11-01). "A 69-Year-Old Woman with Lymphoma and Chylothorax. Looking Beyond the Usual Suspect". Annals of the American Thoracic Society. 11 (9): 1490–1493. doi:10.1513/AnnalsATS.201406-251CC. ISSN 2329-6933. PMID 25423001.
- ^ Sonoda, A; Jeudy, J; White, CS; Kligerman, SJ; Nitta, N; Lempel, J; Frazier, AA (May 2015). "Pleurodesis: indications and radiologic appearance". Japanese Journal of Radiology. 33 (5): 241–5. doi:10.1007/s11604-015-0412-7. PMID 25791777. S2CID 22780289.
- ^ Weese, Scott; Munroe, Dr Graham; Munroe, Graham (2011-03-15). Equine Clinical Medicine, Surgery and Reproduction. CRC Press. p. 476. ISBN 978-1-84076-608-0.
