Presentation on theme: "The Chyle Files: Chylothorax"— Presentation transcript:
1The Chyle Files: Chylothorax Abigail Mariano, VMDSmall Animal Surgery ResidentDecember 20, 2013Chylothorax is a frustrating condition for clinicians and pet owners alike. As I’ll talk about over the next 40 minutes, there is still a lot we do not know about managing this condition. Its not a common disease, but if you havent seen a case of it yet, odds are that you will.
2What is it?Disruption or abnormality of the thoracic duct or tributaries of the lymphatics resulting in accumulation of chyle in pleural space
3Population Dogs and cats Breed predispositions: Afghan hounds, Shiba Inus, Oriental cat breedsNo sex predilectionNo age predilectionI will be talking about it in dogs and cats, though it has been reported in horses, cows, rats, rabbits, ferrets and most animals. Not very much research in species other than humans, dogs, and cats.Shiba Inus tend to be <1 year and Afghan and oriental cats middle to older age
4Presenting clinical signs CoughAbnormal respirationShallow/restrictiveTachypneaOrthopneaAcute respiratory distressCyanosisMuffled heart/lung soundsIncreased bronchovesicular sounds dorsallyWeight lossCoughing may be first and only clinical sign in dogs and catsOrthopnea being when they posture with their elbows abducted and head and neck extendedCan be cyanotic in severe presentationsMay have a history of recent or chronic weight loss
5Effusions Transudate Modified transudate Exudate <1500 nucleated cells/uL<2.5 g/dL total proteinModified transudatenucleated cells/uL2.5-4 g/dL total proteinExudate>7000 nucleated cells/uL>3 g/dL total proteinWhen an animal presents in this condition, in addition to administering oxygen, one of your first diagnostic AND therapeutic steps will be to perform a thoracocentesis.Collect it in an EDTA anticoagulant tube for cell counts and a red top for biochemical analysis (cholesterol, triglycerides) and save some for culture if indicated by the cell countsTransudates are clear and are usually the result of a decrease in intravascular oncotic pressure such as hypoalbuminemiaModified transudates are most commonly due to long standing transudates or an increase in lymphatic or venous hydrostatic pressureExudates have a turbid appearance from the increased cell counts, often due to increased vascular permeabilityFurther effusion classifications include septic or nonseptic inflammation, neoplastic effusion, hemorrhagic effusion, and chylous effusion
6ChyleSo if you get something back that looks like this, you are most likely dealing with a chylous effusion!Milky white modified transudate or exudateComposition: lymph and chylomicronsProtein content unreliable bc of refractive interference of lipidsPredominant cell type is small lymphocyte, with increasing numbers of neutrophils and macrophages with chronicity
7As a reminder: chylomicrons are lipoprotein particles that consist of triglycerides, phospholipids, cholesterol, and a small amount of proteins. They enable transport of the dietary fats and cholesterol from the intestines to other locations in the body by making them water soluble. They travel in the lymphatic system and are released into the bloodstream at the TD connection with the vena cava.
8Fluid diagnostics Cytology, fluid analysis Paired fluid and serum triglyceridesCholesterol : Triglyceride ratioEther clearance testSudan stain for lipid droplets+/- Culture and sensitivityIn addition to the Cytology and I just described. Other diagnostics arePleural triglycerides are often >10 times serum levelsCholesterol/triglyceride ratio <1 in pleural fluid is diagnostic and helpful in anorectic patientsEther test: 2 tubes of pleural fluid, alkalinized with 1-2 drops of sodium or potassium hydroxide. Add ether to one tube, water to the other. A positive test is one where the pleural fluid becomes more clear after ether addition. Ether extracts/dissolves the fatSudan III is a fat soluble stain that will stain for lipid dropletsCulture and sensitivity may be indicated with repeated taps if iatrogenic infection is suspected. Chylous effusion is bacteriostatic by nature(Pseudochylous – pleural cholesterol> serum cholesterol. Assoc with tb)
9Etiopathogenesis Trauma to the thoracic duct (uncommon in animals) Secondary to ANY condition that causes obstruction of the thoracic duct, prevents lymph flow to venous circulation, or increases in lymphatic flowSimple versionChylothorax may result from trauma to the thoracic duct which is uncommon in small animals or it may be secondary to any condition that causes obstruction of the TD or that prevents lymph flow to venous circulation.
10Etiopathogenesis Cardiac disease (congenital or acquired) Pericardial diseaseDirofilariasisPulmonary hypertensionLung lobe torsionDiaphragmatic herniaTraumaNeoplasiaInfection (fungal granuloma)Congenital or acquired abnormalities of the thoracic ductVenous thrombiIdiopathic***Evaluate for underlying diseaseIncomplete list….Cardiac (right sided heart disease, cardiomyopathy, tetralogy of fallot, valvular dysplasia, cor triatriatrum dexer)Pericardial disease or effusionHeartworm diseasePulmonary hypertensionLung lobe torsion, diaphragmatic hernia or other trauma to the TDNeoplasia including heart base masses, cranial mediastinal masses, pericardial neoplasia, and lymphangiosarcomaInfection including Fungal granulomasCongenital or acquire abnormalities of the TDVenous thrombi (cranial vena cava) resulting in elevated hydrostatic pressure of cranial vena cava, Obstruction of the lymphaticovenous junctionIdiopathic are most common.Of all these, chylothorax with a treatable underlying disease carries the best prognosis. Trauma is the #1 cause in people, but is rare in animals. It is associated with a good prognosis- usually mild CS and self limiting 1-2 weeks.[Clinical evidence of venous or lymphatic hypertension never reported, though an experimental model of chylothorax was created by ligation of the cranial vena cava in dogs (fossum am j vet res 1986)]
11Idiopathic chylothorax Failure to identify an underlying causeDiagnosis of exclusionIdiopathic chylothorax is a rule out diagnosis and results from the failure to identify a primary cause. As with most idiopathic diseases, we probably just haven’t recognized the underlying cause yet.
12Other diagnostics CBC/Chem/UA Chest radiographs Heartworm antigen test EchocardiographyThoracic/abdominal CTLymphangiographyCBC often normal +/- lymphopenia, chem can show electrolyte abnormalities consistent with 3rd spacing (hyponatremia, hyperkalemia), hypoproteinemia particularly with more chronic effusionsChest x-rays after tap- look for lung lobe torsion, cardiac silhouette, pulmonary changes, mediastinal masses, ectDirofilaria is reported cause of chylothoraxEcho- congenital or acquired heart conditions can result in chylothoraxCT to look for neoplasia or anything compressingLymphangiography we will talk more about but is important for identifying the lymphatic anatomyBrisson, AJVR, 2006
13Treatment options Medical Management Surgery Definitive Salvage Procedures
14Medical management Low fat diet TPN Medium chain triglycerides? Steroids?Thoracocentesis as neededLow fat diet- goal to decrease lipids content in effusion not volume of effusion. Lower lipid content lends itself to better reabsorption. Staple treatment no matter what else is done for duration of effusionTPN is used to bypass the GI tract and decrease lymph flow by reduction of fat absorption. Seems to work but is a short term option and does not address the problemFeeding MC triglycerides: may be absorbed by portal vein directly, not lymphatics (disproven in 1993 paper – Sikkema- do enter into lymphatics). Not palatableSteroids may help with the inflammatory componentThoracocentesis is not benign. Risk of bleeding, infection, pneumo, ect
15Medical management Rutin (Benzopyrone) 50-100 mg/kg TID, PO Octreotide 10ug/kg TID, SQ daysRutin- benzopyrone--The main function appears to be stimulation of macrophages, which promotes proteolysis within the lymph. Protein fragments can then be reabsorbed into the blood. Rutin is active orally and topically, and is relatively inexpensive, and free of side effects.Octreotide: somatostatin analogue: The exact MOA is not known in chylothorax but it is postulated to work though decrease GI/biliary/pancreatic secretions and reduction of splanchnic blood flow resulting in decreased chylous productionFor both rutin and octreotide the studies have been small and inconclusive. May help and neither appears to be harmful(Sicard, Proceedings of the ACVS 2003Proven to help with traumatic chylous leakage in 8 experimental dogs (Am Surg Dec;66(12): Octreotide in the treatment of thoracic duct injuries.Markham KM, Glover JL, Welsh RJ, Lucas RJ, Bendick PJ.)
16Medical management Good for traumatic chylothorax 2 weeksWhen to go to surgery…Large persistent volume>4 weeksNo studies comparing medical vs. surgical managementMedical management is recommended for at least 2 weeks if chylothorax secondary to trauma is suspected because it is self limiting.No good timeline for when to go to surgery. Large persistent volume >4 weeks. No studies comparing medical management to surgical management. Often animals not responsive to medical management will proceed to surgery.
17Anatomy The path of the lymph fluid Cisterna chyli is abdominal lymph reservoirThoracic duct (TD) arises from cisterna chyliTD is major lymphatic vessel for return of lymph to venous systemTD anatomy varies, especially in idiopathic chylothorax casesDogs: right->leftCats: leftThe mesenteric lymphatics arborize into a large abdominal lymphatic reservoir (cisterna) at approx level of 1st lumbar vertebrae, medial to the left kidney. The hepatobiliary and intestinal lymph all feeds into the cysterna chyli.From cisterna the cranial continuation of the path is the thoracic ductThoracic duct is the major conduit for lymph return to the venous system. It terminates in cranial thorax at the lymphaticovenous junction in the cranial vena cava near where the internal and external jugular veins meetTD usually begins as a single duct but often has multiple branches and variable anatomy, particularly in idiopathic chylothorax casesDogs: the TD runs to right of midline in caudal thorax and crosses to left at approx 5th intercostal spaceCats: on left side throughout its course in the thorax
18Cisterna chyli Brisson, AJVR, 2006 Contrast in the lyphatics highlighting the CC
19Thoracic duct Brisson, AJVR, 2006 Contrast highlighting the thoracic duct. Note the relative tortuosity of the vessels cranially.
20Cartoon: CC is medial to the hilus of the left kidney
21Pre-operative planning LymphangiographyIntestinal (mesenteric)Open, laparoscopic orU/S guidedPoplitealRads vs. Fluoro vs. CTCT shows more branchesMissed branchesPost-op confirmationAthough not necessary, lymphangiography is very helpful. Lymphaniography is the injection of contrast medium into the lymphatics and using the aid of imaging to evaluate the anatomy.This was traditionally done by direct catheterization of the mesenteric lymphatics via opening the abdomen or laparoscopically. In these cases, the best images are taken seconds later so a C arm comes in really handy. It has also been done with ultrasound guidance (though less relaibly due to obvious constraints with visualization).Diagnostic studies can also be achieved with popliteal LN injection of dye, with contrast showing up in the TD on radiographs approximately 10 min later.You can perform lymphangiography with plain radiographs (VD is most helpful view), in real time with fluoroscopy, or with CT. You may need to alter your technique of dye injection based on what imaging is available to you.CT is used most commonly in people and it seems to show the most branches. You also don’t have to worry about superimposition and you get nice 3d reconstructions.** concern with all these techniques that not all branches are equally opacified (some are missed)Immediately post op lymphangiography is also recommended to confirm complete duct ligation or ablation with no remaining tibutaries. However even the value of this is called into question. one study showed that 2 cats that were dissected down to the TD but not actually occluded showed immediate post op lack of contrast cranial to the dissection site as if ligation had occurred. 4 weeks later the lymphangiography was repeated and the TD was patent. False lymphangiogramsNaganobu: -- popliteal injection 4 normal, 1 chylothorax; seen with 1ml/kg at 2ml/ml ; see contrast in approx 10 mins on radsJohnson: CT 5 min after u/s guided mesenteric injection; successful in 6 patientsCT-- used in humans to ID integrity of the thoracic duct described in the 80’s and 90’sEsterline: CT better at several spots, but not every slice on CT. greater contrast resolutionNaganobu, Vet Surg 2006Johnson, Vet Surg 2009Esterline, Vet Rad/US 2005
22Lymphangiogram Sicard et al. Vet Surg 2005 Preoperative lymphangiograms illustrate the diversity of the thoracic duct in different patientsSicard et al. Vet Surg 2005
23Intraoperative identification To identify the lymphatics during surgeryFeed high fat meal prior to surgeryMethylene blueHeterocyclic aromatic compound1% aqueous, 0.5mg/kg (up to 10mg) or 0.2mls dilutedInjected: lymph nodes (popliteal, inguinal, mesenteric), diaphragm, distal limb/paw pad, esophagus or via lymphatic catheterizationComplications: Heinz body anemia, increased ALP, renal failurePreop planning is great, but you need some tricks for when you are in surgery and the lymphatics just aren’t jumping out at you.Feeding a high fat meal like cream or vegetable oil 3-4 hours prior to surgery has also been reported to increase visibility of lymphatic vesselsOne of the most common tools is methylene blue.Methylene blue is a jack of all trades. Besides being a dye compound, other reported scientific properties include neuroprotective, cognitive, and memory enhancing qualities, a chemical redox indicator, a photosensitizer, RNA/DNA stain, cheap treatment for malaria (turns urine green and sclera blue), cancer treatment- selectively inducing apoptosis of cancer cells, has virusidal properties and been used in treatments for everything from HIV to Hepatitis C to west nile virus, to plaque psoriasis, also used to treat cyanide and carbon monoxide poisoning to name a few….
24Methylene blueThis graph from this 2003 study compares methylene blue injected at the mesenteric LN or popliteal. No significant time delay, both sites reached maximum coloration of the TD at 10 minutes, though the popliteal injection site never achieved the same intensity of coloration. The investigators stopped the study at 60 minutes at which time dye was still present and highlighting the lymphatics. We don’t know how long it would stay, but 60 minutes was deemed sufficient time to identify and ligate the branches of the TD.Enwiller, Vet Surg 2003
25Methylene blue Sicard, Vet Surg, 2003 This photograph is the view of a right 11th intercostal thoracotomy. The thoracic duct is weakly visible.This photograph is the same view following injection of methylene blue into the lymphatic system. You can see the usefulness and importance of the injection to allow complete visualization of the thoracic duct for adequate ligation.Sicard, Vet Surg, 2003
26Methylene bluePicture of a methylene blue injection into a mesenteric lymph node and the thoracic duct lit up in blueEnwiller, Vet Surg 2003
27Surgical Options Thoracic duct ligation Pericardiectomy Cisterna chyli ablationOmentalizationEmbolizationShuntsPleural PortPleurodesisPleural strippingAnything with this many different options should tip you off that we don’t know the best one…Multiple procedures- usually a combination performed- no one magic bullet
28Thoracic Duct Ligation Ligation of the thoracic duct is thought to allow the redirection of chyle away from the thoracic duct into new lymphaticovenous anastomoses in the abdomen. The abdomen is more equipped to handle reabsorption of chyleRedirection of chyle away from the thoracic duct into new lymphaticovenous anastomoses[Image modified from JAAHA, 18:769-77, 1982]
29Thoracic Duct Ligation: Open First reported in 1958Goal: occlude duct at entry to thorax, encourage lymphaticovenous anastomoses in abdomenApproach9th-10th intercostal thoracotomy (L cat, right dogs)Transdiaphragmatic in cats and small dogsWant to ligate as far caudally as possible- few branches. Can ligate them individually or en block meaning everything dorsal to the aorta and ventral to the sympathetic trunk (even including azygous vein with no ill effects). Hard to get all the tiny branches, some can be adhered to the aorta. You can use hemoclips or nonabsorbable suture. Can also ablate with the use of ligasure to heat, denature, and seal the ducts.MacDonald VS 2008- cadaver study- 93% occluded with en bloc ligation (13/14 )- may obviate need for lymphangiography- performed in people- Bonavina 2001- ok to ligate azygousControversy over efficacy of post-operative imaging ******Yes: birchard jaaha 1982, javma 1998, no Kerpsack: recurrence in 5/18 cats even though post op confirmed occlusion of TDSmall branches may not fillSuccess rate50-60 % in dogs even w/lymphangiography pre & post ligation20% to 40% in catsFossum TW. Feline Chylothorax. Compendium 1993; 15:Goal: occlude duct at entry to thoraxApproach9th-10th intercostal thoracotomyTransdiaphragmaticDorsal to aorta, ventral to sympathetic trunkIndividual vs. en blocLigation vs. ablation
30Thoracic Duct Ligation Incomplete ligation will result in failure but it is also thought that the failure can result from the formation of collateral lymphatics that bypass the ligature site.Failure may occur due to incomplete ligation or formation of collateral lymphatics that bypass the ligature site instead of forming new lymphaticovenous drainage sites
32TDL: ThoracoscopicGoal: TDL without morbidity of thoracotomy, improved visualizationApproachSternal (or lateral)2 instrument ports to allow dissection dorsal to aortaEvaluate contralateral hemithorax for branchesmay be better able to access further caudally;Can use clips, harmonic scalpel, ligasureMayhew JAVMA 2012; Allman, Radlinsky Vet Surg 2010; Sakals Vet Surg 2011; Radlinsky Vet Surg 2002; Leasure Vet Surg 2011
33More technically challenging More technically challenging? Similar success rates to the open proceduresSingh, 2012
34Pericardiectomy Goal: decrease right sided venous pressure Approach Intercostal, median sternotomy, transdiaphragmatic, thoracoscopic (paraxyphoid or intercostal)Pericardial window or subtotal pericardiectomyExcise pericardium ventral to phrenic nervesInitially developed as a salvage procedure for animals with persistent chylous effusion following TDL but it is now commonly performed in conjunction with TDL to maximize likelihood of positive response. Not usually done soloChylothorax leads to thickened pericardium or thick tissue overlying the pericardium from the chronic irritation of chyle. this in turn may increase systemic venous pressure further, contributing to more fluid build up and these abnormal venous pressures may act to impede drainage of chyle into the cranial vena cava while increasing lymphatic flow through the TD.The goal of the pericardiectomy may lower right-sided venous pressures. However, not all cases of elevated r sided p lead to chylothoraxs(Take down the mediastinum Chronic effusions are irritating and cause pleural/pericardial thickening In original reports (for both open and thoracoscopic procedures) excellent outcome in some authors’ handsSubsequent reports vary 57%-100%fossum jvim 2004Tdl + Pc9d 10c, 100%d 80% c, incl one dog with just s/s eff post tdl theory- thickened peril by chyle-- right sided venous plymphangiography not successful in any cats!!Carobbi vet rec 200813/14 dogs resolved following tdl/pc, 1 req re-op but then resolvedPara xiphoid approach is more complete than intercostal. Port in r/l paraxiphoid, then an intercostal space ventral to lungsFossum, JVIM 2004, Carobbi Vet Rec 2008, McAnulty VS 2011
36Cisterna chyli ablation Goal: reroute lymphatic drainageMajor abdominal vessels, mesenteric root, azygousAvoid lymphatic hypertensionseen with TDLUsually performed with TDLApproach: ventral midline or paracostal incisionMobilize kidney, excise tissueGoal of rerouting or disrupting lymphatic drainage to form new lymphaticovenous junctions with major abominal vessels, mesenteric root, azygous vein and avoid lymphatic hypertension with TDL which may contribute to collateralization.Approach: ventral midline or left paracostal incision, transdiaphragmatic and minimally invasive approaches possible.Incise the peritoneum lateral to the left kidney, mobiilize and retract the kidney medially. Inject an ileocecal LN with methylene blue to help with identification, then sharply excise all visible membranes of the CC and associated lymphatic connections to the caudal TD.Can leave the kidney mobile or tack it back inplaceExperimental study in 6 healthy beagles- led to direct intra-abdominal lymphaticovenous anastomoses– shunting to abdominal vasculature! (To azygous in 3 dogs w/o CCA)Pics- shunt to azygous vs. directly to CVC , phrenicoabdominal, or mesenterics, 1 reconnected to CC azygousStaiger- combined right paracostal approach for TDL, CCA, and pericardectomy (6/6 w all 3 did well, 2/4 w/o peric recurred)Hayashi- TDL r caudal intercostal, CCA left flank or midline (better)Sakals: transabdominal vs transdiaphragmatic approaches (TD 100%, 71% TA); risk of aortic laceration!– ideally to be performed thru scope-TDL portals
37Cisterna chyli ablation Realistically this is nearly always done with TDL.Hypertension caused by thoracic duct ligation alone can result in the development of collateral lymphatics and the redevelopment of chylothoraxThe disruption of the cisterna chyli will relieve lymphatic hypertension and promote new routes of lymphatic drainageAlso proposed to omentalize the CCA site but this has not shown to change outcome.Combining cisterna chyli ablation with thoracic duct ligation[Image modified from JAAHA, 18:769-77, 1982]
38This image is taken within the abdomen via a ventral midline celiotomy This image is taken within the abdomen via a ventral midline celiotomy. The cisterna chyli, highlighted by the injection of MB, is seen just caudal to the left lateral lobe of the liver. The left kidney is being retracted medially.The cisternal membranes are removed until the aorta is reached. The omentum is pulled into the area and tacked to the abdominal wall.Sicard et al. Vet Surg 2005
39This is an image with the abdominal cavity illustrating the arborization of the abdominal lymphatics several weeks following the procedure. Tough to tell in the picture but they are draining into vessels in the abdomen
401 month post TDL with CCA Sicard et al. Vet Surg 2005 Caudal vena cava In 3 of the dogs 1month after TDL and CCA they performed a lymphangiogram and saw diffuse arborizing lymphatics. They appeared to be direct lymphaticovenous anastomoses since the contrast rapidly dissipated with continued injection.(In the remaining 3 dogs, direct shunting into a major vein was observed.2 dogs had direct shunting into the caudal vena cava.And in one dog there was shunting into the azygos vein.)Azygos veinSicard et al. Vet Surg 2005
41Omentalization Goal: provides absorptive surface? Angiogenesis Drains back to TDAngiogenesisSource of immune cellsDiaphragmatic incisionOr- subcutaneous tunnelTack intrathoracicallySalvage vs Ancillary procedureOmentum is a natural drain so exploited this function to remove chyle from thorax. May also help seal the leaking TDHowever, the omentum drains lymph back into the TD, so in that sense it is kind of pointlessAlso has angiogenic and immune propertiesPass it into chest through diaphragmatic incision of SQ tunnel and tack to the mediastinum. Avoid constricting, kinking or twisting it as you move it to the chestOriginally described as ‘salvage’ procedures in a dog and cat, where conventional surgery (i.e. TDL) could not be achieved because thickening prevented identification of the structuresNow considered an ancillary procedure when combined with TDL or TDL & pericardectomy.(Interestingly TDL/P/O added no benefit over TDL/P alone. Bussadori et alWilliams Vet Surg 1999LaFond Jaaha case report of a cat who failed TDL, had restrictive pleuritis, resolved with omentalizationDa Silva JAVMA dogs with omentalization were more likely to resolve (2/3 w/o oment recurred, 8/8 with resolved))
42OmentalizationOmentum being pulled through the diaphragm into the thorax
43EmbolizationCyanoacrylate glue injected into cannulated mesenteric lymphatic vesselOccluded 100% of TD in healthy dogs, but 33% clinical efficacyRisk of emboli in circulation, lungsSalvage procedure?Cyanoacrylate injected through a mesenteric lymphatic catheter to embolize CC and TD. Mix glue with contrast so it can be done under fluoro guidance with lymphangiographyWorked in 8/8 normal dogs (8) but only 2/6 33% idiopathc chylothorx (2/6) Described as a salvage procedure for those failing management due to its low clinical success rate but has potential as first line treatment. Need more studies. It is a technique commonly performed in humans.Adv- direct visualization of TD not requiredDisadv- incomplete filling of tributaries with glue, collateralization, risk of emboli in circulation and lungsPresented at ACVS- Pardo 1995 (experiment Pardo 1989)Inject at the level of T10-13Performed in children with chylothorax successfully +/- endovascular microcoil to hold the gluePediatrics Jul;128(1):e doi: /peds Epub 2011 Jun 6.Percutaneous thoracic duct embolization as a treatment for intrathoracic chyle leaks in infants.Itkin M, Krishnamurthy G, Naim MY, Bird GL, Keller MS.Madeline Miller – case from 2010Treatment of choice for people with traumatic chylothoraxExperimental model in dogs (1989)Case report (AMC, Penn & Tufts 2010)Mesenteric injection of glueAvoids thoracic surgery, embolizes cisterna too and may get TD branchesNo significant complicationsPhotos courtesy of WeisseSingh, Am J Vet Res 2011; Pardo ACVS 1995; Weisse JAVMA 2008
44Percutaneous catherization & embolization Percutaneous catheterization of cisterna as an even less invasive optionPunctured 9/15, catheterized 5/9Advance wire into thoracic ductEmbolize with microcoils and either cyanoacrylate or ethylene vinyl alcohol4/4 successful…. So 4/15. technically demanding(Substantial increase in TD pressureTheoretically could make effusion worse)Singh et al. AJVR 2011
45Shunts Salvage procedure Pleuroperitoneal- active Pleuroperitoneal- passivePleurovenous shuntOverall shunts have a high rate of complications (72%) , but high rate of owner satisfaction- SmeakMST 27 months, DFI 20moSalvage procedurePleuroperitoneal- activeDenver catheterKinking, infection, dislodgement, obstruction, abdominal distension, seedingPleuroperitoneal- passiveFenestrated silastic sheetObstructionPleurovenous shuntTechnical difficulty, thrombosis, migrationSmeak et al, JAVMA 2001Willauer JAVMA 1987Peterson Vet Surg 1996
46Pleuroperitoneal active shunts Described 14 dogs with chronic effusions – 10/14 had chylothorax. More successful with the nonchylous effusionsAfferent fenestrated side placed in thoracic cavity, efferent side place in peritoneal cavityDenver pump with one way valve placed under external abdominal oblique over a rib. Pumped daily as needed to control clinical signs. Each pump is 1ml.Was quite effective as a palliative measure but with adverse effects common in the short (e.g. Getting kinked, infection, owner compliance) and long term (e.g. Obstruction of shunt, pyothorax, abdominal distension).No successful reports in catsCannot use if there is a generalized impairment to fluid resorption from the body (e.g. Right sided failure, diffuse lymphatic pathology).Overall good respiratory outcome (e.g. Not short of breath) for a mean of 20 months, survival overall mean 27 months. (all effusions mixed)Smeak et al. JAVMA 2001
47Pleuroperitoneal passive shunts Fenestrated silastic sheet placed in defect created in diaphragm or transdiaphragmatic tubesProvides drainage into abdomenReabsorption via visceral and peritoneal lymphaticsShunting drive by respirationLongterm patency of drains discouragingFibrin clots, adhesions, omentumPleuroperitoneal- passiveAided in movement by respirationFenestrated silastic sheetObstructionProsthetic mesh rapidly obstructed
48Pleurovenous shuntsPleurovenous shuntTechnical difficulty, thrombosis, migrationDenver catheter (inserted into veins vs other)Efferent side placed in the azygous vein or caudal vena cavaCan be tunneled to ventral cervical region and inserted into jugular vein & down to cranial vena cavaNot really recommended in vet med.
49PleuralPort Percutaneous (or open) Port function 1-391 days Incision over 10th ribTunnel 2-3 spaces craniallyOr-- place 1st, then tunnel caudallyPort function daysMedian 20 daysComplicationsKinking, migration, leakage, hemithorax access, obstruction, pocketingPlace as conjunctive therapy?Percutaneous (or open)Incision over 10th ribTunnel 2-3 spaces craniallyRetract incision dorsally, suture to SQOr-- place 1st, then tunnel caudallyOriginally described as salvage or palliative procedure for intractable effusion but I would argue that these should be placed in surgery. Even if the definitive surgical procedure is successful, it takes an average of a couple weeks for the effusion to resolve. This provides a minimally invasive way to empty the chest cavity in the mean time. Nonsqueamish owners can fairly easily be trained to use this. Better option than chest tube which is too risky to send animal home withBrooks et al- 6 dogs, 4 cats, 11 ports, 9 percutaneouslyObstruction in 3 casesPort function days (median 20 days), in place for d.Rec hep with 100iu/ml?Brooks, Vet Surg 2011
51Out-dated modalities… PleurodesisTalc, blood, antibiotics, mechanical abrasionsDo not form adhesions in dogsPainDecortication (pleural stripping)HemorrhageIntractable pneumothoraxPleurodesis is the attempt to obliterate the pleural space by stimulating adhesions to form between the visceral and parietal pleura. Effective in humans but not shown to work in dogs(tetracylcine HCl, quinacrine HCL, bleomycin, fluorouracil, talc)Fossum thoracoscopic pleurodesis- not adhesionsDecortication- attempts in patients with fibrosing pleuritis to peel off the scar tissue left behind
52Success: By the numbers ProcedureSuccess RateRutin67%* (cats)1Octreotide40%2TDL50-59% (dogs)% (cats) 3TDL + SP60-100% (dogs)80% (cats) 4Thoracoscopic TDL + SP% (dogs)5TDL + CCA% (dogs)6TDL + SP + omentalization72.7% (dogs) 757% (d+c) 8MST 209d (c) 211d (d) 9Embolization33% 101.Total of 6 cats in 3 reportsThompson JAVMA 1999Gould Can Vet J 2004Kopko Can Vet J 20052. Sicard Vet Surg 20033. Most studies in 1980s/1990s, various techniques: (Birchard JAVMA 1998; Harpster CVT 1986; Viehoff german 2003; Birchard JAAH 1982; Birchard JAVMA 1998; Fossum JAVMA 1999; Kerpsack JAVMA 1994)4. Dr Fossum has reported excellent success with this and subsequent studies slightly less so. Surgeon experience? (Fossum JVIM 2004; Carobbi Vet Rec 2008; McAnulty Vet Surg 2011)5. Less invasive option, similar outcomes to open technique: (Allman VS 2010; Mayhew 2012)6. Staiger VS 2011Hayashi VS 2005McAnulty Vet Surg 20117. Da Silva JAVMA 20118. Bussadori Vet J 20109. Stewart JAAHA 201010. Need more studies: Pardo et al Proc ACVS 1995Variability in time to resolution of effusion 1-50 days notedHOWEVER: McAnulty et al VS 2011: 60% with TDL-SP, 83% with CCA-TDL (not stat sign)- Salvage procedures are recommendedAlso, non-chylous effusionRecurrence can be seen as long as 5 years post opAdapted from Singh. Compendium 2012
53Progression and sequelae Fibrosing pleuritisInflammatory changes to mesothelial cellsIncrease type III collagenDecreased fibrinolysisRestrictive pleuritisFailure to expand lungs despite thoracocentesisPericarditisMalnutrition, dehydration, loss of lipids, protein, fat-soluble vitamins, lymphocyte depletionFibrosing pleuritis can develop with any effusions thought to cause chronic inflammation. High fibrin formation-> mesothelial desquamation, increased permeability, increase type III collagen resulting in promoted fibrosis. Chronic pleural effusion may lead to impairment of fibrin degradation and dilution local plasminogen activator (for fibrinolysis).Restrictive pleuritis is a manifestation where Pleura is thickened by diffuse fibrous tissue that restricts normal pulmonary expansion. Can be misdiagnosed by having a large amount of pleural effusion (rounding of lobes). If you can’t get a lot of fluid out, be suspicious of atelectasis and fibrosis of the lungs secondary to this condition. Caution because you can very easily give them a pneumo trying to tap the effusion. CT may be better than x-rays because it is hard to differentiate persistent effusion vs fibrosisOther sequelae include pericarditis and malnutrition….
55Take-home points Idiopathic is most common Diagnosis based on appearance, cytology, triglyceridesMedical management frequently failsNo ONE surgical technique to recommendTDL, CCA, pericardectomy and pleuralport?More minimally invasive techniques emergingPost-operative lymphagiograms may or may not be helpfulHigh morbidity with long term effusion
56ReferencesAllman DA, Radlinsky MG, Ralph AG, et al: Thoracoscopic thoracic duct ligation and thoracoscopic pericardiectomy for treatment of chylothorax in dogs. Vet Surg 39:21, 2010.Brooks A. et. al. Vet Surg Use of the PleuralPort device for management of pleural effusion in six dogs and four cats.Bussadori et al. Pleural omentalisation with en bloc ligation of the TD and PC for IC in 9 dogs and 4 cats. Vet J 188: , 2011Carobbi B, White RAS, Romanelli G: Treatment of idiopathic chylothorax in 14 dogs by ligation of the thoracic duct and partial pericardectomy. Vet Rec 163:743, 2008Chun H, Cho H, Cheon H, et al: Determination of optimal dosage and delay time for computed tomographic lymphangiography after percutaneous injection of iohexol into popliteal lymph nodes in dogs. J Vet Med Sci 71:873, 2009.DaSilva CA, Monnet E. Long term outcome of dogs treated surgically for idiopathic chylothorax:11 cases ( ). JAVMA 239: ,2011Enwiller TM, Radlinsky MG, Mason DE, et al: Popliteal and mesenteric lymph node injection with methylene blue for coloration of the thoracic duct in dogs. Vet Surg 32:359, 2003.Esterline ML et al: Comparison of radiographic and CT lymphangiography for identification of the canine thoracic duct. Vet Radiol Ultrasound 2005;46:Fossum TW. Chylothorax in cats: is there a role for surgery? J Fel Med Surg 3:73-79, 2001Fossum TW, Mertens MM, Miller MW, et al: Thoracic duct ligation and pericardectomy for treatment of idiopathic chylothorax. J Vet Intern Med 18:307, 2004.Hayashi K, Sicard G, Gellasch K, et al: Cisterna chyli ablation with thoracic duct ligation for chylothorax: results in eight dogs. Vet Surg 34:519, 2005.Hinrichs et al. Lymphangiosarcomas in cats: a retrospective study of 12 cases. Vet Path 36: , 1999Johnson EG et al. Computed tomographic lymphography of the thoracic duct by mesenteric lymph node injection. Vet Surg 38: ,2009.Itkin M et al. Percutaneous thoracic duct embolization as a treatment for intrathoracic chyle leaks in infants. Pediatrics 2011 Jul;128(1):e237-41Kerpsack et al. Evaluation of mesenteric lymphangiography and TDL in cats with chylothorax: 19 cases ( ). JAVMA 205(5):711-5, 1994Kovak JR, Ludwig LL, Bergman PJ, et al: Use of thoracoscopy to determine the etiology of pleural effusion in dogs and cats: 18 cases (1998–2001). J Am Vet Med Assoc 221:990, 2002LaFond E, Weirich WE, Salisbury SK: Omentalization of the thorax for treatment of idiopathic chylothorax with constrictive pleuritis in a cat. J Am Anim Hosp Assoc 38:74, 2002.McAnulty JF. Prospective comparison of cisterna chyli ablation to pericardectomy for treatment of spontaneously occurring idiopathic chylothorax in the dog. Vet Surg 40: , 2011.Naganobu et al: Lymphgraphy of the thoracic duct by the percutaneous injection of iohexol into the popliteal lyph node of dogs: experimental study and clinical application. Veterinary Surgery 35: , 2006.Pardo AD, et al. Transcatheter thoracicduct embolization in the dog. An experimental study. Vet Surg1989;18:279–285.Peterson SL. Postcaval thrombosis and delayed shun migration after pleuroperitoneal venous shunting. Vet Surg 25: , 1996.Radlinsky MG, Mason DE, Biller DS, et al: Thoracoscopic visualization and ligation of the thoracic duct in dogs. Vet Surg 31:138, 2002.Sicard GK et al: The use of a somatostatin analogue for the treatment of idiopathic chylothorax in dogs and cats. Proceedings ACVS 2003.Sikkema DA, McLoughlin MA, Birhcard SJ. Effect of dietary fat on triglyceride and fatty acid composition of thoracic duct lymph in dogs. Vet Surg 1993;22:Smeak DD, Birchard SJ, McLoughlin MA, et al: Treatment of chronic pleural effusion with pleuroperitoneal shunts in dogs: 14 cases (1985–1999). J Am Vet Med Assoc 219:1590, 2001.Staiger et al: single paracostal approach to thoracic duct and cisterna chyli: experimental study and case series. Vet Surg 40: , 2011Weisse et al: Potential applications of interventional radiology in veterinary medicine. JAVMA 233:1564, 2008