Ch 105 Throacic cavity Flashcards
Anatomy
- the normal pleural space is lined by a single layer of mesothelial cells
- pleura is usually described as parietal or visceral (pulmonary).
- Parietal pleura consists of costal, mediastinal, and diaphragmatic portions
- ventral mediastinal pleura forms recesses that cradle the ventral borders of the lung lobe
- It is not clear whether mediastinal pleura completely separates the thoracic space into right and left pleural cavities in dogs and cats
- pulmonary ligament: triangular fold of relatively avascular pleura on caudal lung lobe.
- plica venae cavae
what is normal plural fluid volume in dogs and cats?
Dog - 0.1ml/kg
Cats: 0.3ml/kg
What cells make up normal plueral fluid?
mesothelial cells 9-30%
Monocytes/macrophages 61-77%
Lymphocytes 7-11%
Neutrophils under 2%
1500-2500 cells/mcL
Protein less than 2.5g/dL
Lymph Nodes
- mediastinal lymph nodes are confined to the cranial mediastinum and along the surface of the heart
- bronchial lymph center includes the pulmonary and tracheobronchial lymph nodes
- Pulmonary lymph nodes, which are not present in all dogs
- sternal lymph node or a single median node
- aortic thoracic nodes
What % of dogs have a dorsal thoracic lymph centre?
25%
Thoracic Duct
- It begins in the sublumbar region, or between the diaphragmatic crura, as a continuation of the cisterna chyli
- There are significant anatomic variations in the configuration and number of thoracic duct branches and intercommunications in dogs and cats
Which parts of the body are NOT drained by the thoracic duct?
Right thoracic limb
Right shoulder
Cervical regions
Drained by the right lymphatic duct
What is the cisterna chyli and where is it located?
- Bipartite, dilated, retroperitoneal lymph channel, ventral to L1-L4 along cranial abdominal aorta
- In dogs, it most commonly lies on the right
- Most cmmonly sits ventral to L3, caudal to coeliac and cranial mesenteric arteries
What is the major difference in the thoracic duct anatomy in dogs and cats?
Dogs - travel on right sife through caudal thorax, dorsolateral to aorta. Crosses to left at T5/6
Cats: On the left!
Where does the thoracic duct drain?
Left external jugular vein or jugulosubclavian vein
(Significant anatomical variation - some branches may terminate in azygous)
What embryonic structure forms the thymus?
At what age does it stop growing and starts to involute?
- Arises from the 3rd pharyngeal pouch
- Grows until 4-5mo, then involutes
receives its arterial supply from the internal thoracic arteries
Histologically, the thymus consists of small lymphocytes
within ventral mediastinum and may be bilobed.
What is the normal functional residual capacity (volume of air remaining in lung at end of expiration)
45ml/kg
represents the point at which all forces, including collapse of the lungs and expansion of the chest cavity, are in passive equilibrium
What fluid dynamics favour pleural fluid production and absorption?
- Increased hydrostatic pressure of systemic and pulmonary capillaries compared to pleural fluid favours pleural fluid production
- Increased osmotic pressure of systemic and pulmonary vascular beds are greater than pleural fluid, favouring absorption
Tends to enter pleural space from parietal pleura and be absorbed by visceral pleura
Respiration
- Active and passive movements of the diaphragm and thoracic wall alter pleural pressure, resulting in changes in pulmonary volume and subsequent gas exchange within the lung
- Pleural fluid mechanically connects the visceral and parietal pleura; thus, outward movement of the thoracic wall and diaphragm results in negative airway pressure and subsequent lung expansion as long as transthoracic (intrapleural) pressure is enough to overcome airway resistance and inward elastic recoil of the lungs
- Peak inspiratory pleural pressures of anesthetized dogs mean −9.34 cm H2O.
- Mean inspiratory intrapleural pressures in awake dogs −26.8 ± 20.8 cm H2O
- Negative inspiratory pressure draws air into the airways and to the lungs
- exhalation is primarily passive as a result of inward elastic recoil of the lungs and thoracic wall with diaphragm relaxation.
- End-expiratory pleural pressure of anesthetized dogs mean −5.12 cm H2O
- Mean expiratory intrapleural pressure in awake dogs −15.0 ± 17.5 cm H2O
Minute ventilation
- determined by the volume taken in with each breath, known as tidal volume, and the number of breaths per minute, or respiratory frequency.
- To meet increasing oxygen demands, an animal must increase its tidal volume, respiratory frequency, or both
Fluid Gradients (pleural fluid)
- Fluid production in the pleural space is based primarily on the relationship of hydrostatic and colloid osmotic pressure differences between the capillary and lymphatic beds of the parietal and visceral pleura.
- The Starling law describes the effects of differences in pressure on net filtration.
What are the functions of the thymus?
Cell mediated immunity
- maturation and selection of T-cells
- Termination of defective or autoreactive thymocytes
Endocrine
- Secretion of thymosin, thymic humoral factor, thymopoietin, thymostimulin, thymulin
- Involved in T-cell enhancement and maturation
pathophysiology
Causes of Pleural Abnormalities:
- Mechanical interventions (positive-pressure ventilation, thoracotomy, thoracoscopy).
- Trauma (open chest wounds, rib fractures, flail chest).
- Pleural space accumulations (air, fluid, tissue).
Pneumothorax:
- Leads to lung collapse (atelectasis) and ventilation-perfusion (V/Q) mismatch.
- Severe cases may cause a “sprung” chest appearance due to increased thoracic volume.
Pleural Effusion
- Caused by changes in hydrostatic pressure (RHS heart failure), osmotic pressure (hypoalbuminaemia), vascular permeability (inflammation), or lymphatic drainage.
- neoplasia, trauma, lung lobe torsion, and coagulopathies.
Hemothorax
- result from trauma or abnormal vessels (e.g., tumors).
Physiological Impact of Pleural Effusion:
- Increased pleural fluid raises central venous pressure (CVP), affecting cardiac function.
- Severe cases may mimic cardiac tamponade and resolve with effusion drainage.
Chronic Effects of Pleural Space Disorders:
- alter pulmonary compliance and gas exchange, causing respiratory distress after air removal.
- Reexpansion Pulmonary Edema (RPE) may occur post-drainage and has been reported as fatal in severe cases, especially in kittens.
How do you classify pleural transudate, modified transudate and exudate?
List causes of a pleural transudate
Hypoproteinaemia
Increased hydrostatic pressure as with CHF (NT-proBNP significantly higher in cats with effusion from heart disease)
ist DDx for a serosanguinous (modified transudate) effusion (6)
Lung lobe torsion
D-hernia with liver entrapment
Pericardial effusion
Right sided heart failure
Neoplasia (diffuse mesothelioma or carcinomatosis)
Idiopathic pleuritis
List DDx for a sanguinous effusion
Trauma
Coagulopathy
Acute lung lobe torsion
Iatrogenic
Tumours (chemodectoma, right atrial HSA)
List DDx for chylous effusion
Any condition that increases hydrostatic pressure in the cranial vena cava
Trauma
Idiopathic
How do you confirm chylothorax?
- Triglycerides higher and cholesterol lower than serum
- Chylomicrons in the fluid can be stained with Sudan black
- Positive ether clearance test
- Modified transudate (protein 2.5-4g/dL, cell count less than 7000/mcL, specific grav leass than 1.032
List DDx for inflammatory effusion
modified transudates or exudatesmodified transudates or exudates
D-hernia
Neoplasia
Chronic chylothorax
Lung lobe torsion
Infectious disease (pyothorax)
Pancreatitis
Penetrating FB
Oesophageal trauma
Repeat thoracocentesis
Surgery
Oropharyngeal flora are most commonly isolated from cats
diagnosis
- A restrictive breathing pattern, characterized by rapid and shallow ventilation
- dyspnea and tachypnea
RADS:
- as little as 100 mL of fluid in a dog and 50 mL in a cat can be detected radiographically
- interlobar fissure lines; retraction of the lung borders from the chest wall; and loss of detail, cardiac silhouette, or diaphragmatic line.
- thoracic cavity abnormalities m
Ultrasonography
- mediastinal masses and cardiac abnormalities
- guide thoracocentesis and aspiration
CT
- etect pulmonary metastasis, mediastinal and thoracic wall mass lesions, undiagnosed pleural effusion, lung lobe torsion, bullae or blebs associated with spontaneous pneumothorax, and pathologic changes associated with foreign bodies
What is the reported rate of pneumothorax and haemorrhage after a CT-guided lung FNA?
Pneumothorax 0-27%
Haemorrhage up to 30%
Usually minimal and require no treatment
Thoracocentesis
- dyspnea and a high index of suspicion for pleural effusion should prompt immediate thoracocentesis and oxygen administration before other diagnostic tests are performed
- EDTA) and clot tubes for cellular and biochemical analysis, sterile for C&S
- cytology and measurement of nucleated and total red blood cell counts; specific gravity; and total protein, triglyceride, and cholesterol
technique
- dorsal one-third for air
- Connection of the needle or catheter to a syringe with flexible tubing is strongly advised to prevent movement of the needle during syringe aspiration
- bevel perpendicular to the thoracic wall for insertion, then 45 degree
What is the most realiable way to differentiate transudates and exudates in cats?
- Pleural fluid lactate dehydrogenase
- Ratio of pleural fluid to serum TP.
Senstivity, specificity and accuracy 100% with a cut off for lactate at 226IU/L
Accuracy of TP ratio 95% with a cutoff greater than 0.56
What is a relaible measurement to differentiate transudaet and exudate in dogs?
CRP greater than 4mcg/ml 100% sensitive and 94% specific
11mcg/ml 88% sensitive and 100% specifice for differentiating modified transudate and exudate
What ICS is used for thoracocentesis?
7-9th
presurgical consdieration
- stabilized before consideration of thoracic surgery
- monioring (CVC)
- Oxygen supplementation and fluid therapy
- treate underlying cause
- Pleural fluid or air resulting in hypoventilation should be eliminated by thoracocentesis
- small-bore wire-guided chest drains under sedation
- traditional larger bore under GA
What effect does mechanical ventilation have during anaesthesia on the lungs and heart?
In closed chest, increases intrapulmonry pressures to 3-5cmH2O
This decreases coronary circulation, pulmonary circulation and venous return to the heart
Inspiratory:expiratory phases should be kept between 1:2 to 1:3
Standard Thoracostomy Tube Placement
- premeasured to avoid entering the most cranial extent of the mediastinum,
- skin incision in the dorsal third of the tenth or eleventh intercostal space, tunneled in the subcutis
- inserted into the chest through the seventh or eighth intercostal space in the midthorax (distance between the fist and skin should be the approximate thickness of the chest wall)
- tube penetrates the pleura, the stylet is aimed at the contralateral elbow
- “Chinese fingertrap” pattern or
In which ICS is a thoracostomy tube placed?
7th or 8th
What is the recommended amount of crossing of a finger-trap
Spaced apart approx equal to width of tube with atleast 6 crosses on each side
What has been shown to be more effective at preventing leakage around the chest tube?
Trocar tipper tube for tunneling rather than Carmalt forceps
Polyvinyl tubes more effecting than red rubber
Wire-Guided Thoracostomy Tube Placement
- small-bore (e.g., 14 gauge) wire-guided chest drains (MILA International) can be performed using a modified Seldinger technique
- introducer catheter over stylet, guide-wire, catheter is removed, leaving the wire in place, and the chest drain is advanced over the wire
Tube Management
- drainage may be intermittent or continuous
- Intermittent > non–life-threatening or postoperative monitoring and analgesia. Between aspirations, the clamp is compressed with a metal C-clamp
- Continuous drainage may be required for medical management of pneumothorax, chylothorax, or pyothorax.
- continuous drainage provide a water seal to avoid air entry into the chest
- usually maintained at 5 to 10 cm H2O
- air cannot be measured with continuous suction, but its presence can be detected in the form of air bubbles
complications
22%
- discharge around the thoracostomy tube,
- accidental removal,
- blockage,
- subcutaneous emphysema.
- air leak
tube removal
- fluid may increase on day 3 in some animals because of this tissue reaction.
- No significant difference was found in the time of discharge for patients with more and less than 2 mL fluid/kg/day at the time of tube removal.
- The time of tube removal should therefore be based on multiple parameters such as patient status; individual disease process; and results of follow-up diagnostic tests, such as radiographs, fluid cytology, and cultures.
What is the recommended ICS for surgical approach to the following structures
- Heart and pericardium
- PDA, PRAA
- Pulmonic valve
- Cranial lung lobe
- Middle lung lobe
- Caudal lung lobe
- Cranial oesophagus
- Caudal oesophagus
- Cranial vena cava
- Caudal vena cava
- Thoracic duct in dog and cat
thoroscopy complictations
- same as for thoracotomy or median sternotomy;
- morbidity is considered to be lower with a more minimally invasive approach.
- Port-site metastasis has been reported
- severe complications of thoracoscopy (e.g., hemorrhage, pneumothorax) necessitate immediate conversion to thoracotomy
- adhesions may also limit the ability to visualize the entire thorax,
post-op
Monitoring
- ICU
- Blood gas analysis (hypoventilation)
- Indirect measures, including mucous membrane color, capillary refill time, mentation, indirect blood pressure, and oxygen saturation
- thoracostomy tube should be intermittently aspirated to evaluate for unexpected accumulation of blood, fluid, or air.
analgesia
- parenteral analgesics (e.g., opioids, nonsteroidal antiinflammatory drugs) combined with local anesthetic administered intercostally or intrapleurally
- Bupivacaine or lidocaine (1.5 mg/kg)
- Some avoid lidocaine CRI in cats dt potential toxicity and cardiovascular depression.
What is the mortality rate of thoracotomies?
What factors are associated with nonsurvival?
Mortality rate 13-22% (5.9% in another study)
Factors assoc with nonsurvival:
- Preanaesthetic O2 requirement
- Use of neuromuscular blocking agents during anaesthesia
- Surgical duration over 180min
- Blood products
Wound complications occur in 22% to 71% of patients after thoracotomy
Trauma
- greatest injury to the thorax in cats and dogs occurs with bite wounds
- rib fractures (46% to 88%), pneumothorax (34% to 67%), pulmonary contusions (52% to 67%), and pleural effusion (16% to 22%)
- In cats with high-rise syndrome, 13% to 33% have thoracic trauma
- concurrent injuries common
- Radiographic findings are not helpful in predicting which patients require thoracotomy after bite wounds
- visceral trauma is suspected, surgery should be considered on an emergent basis
- thoracostomy tube may allow stabilization in the face of significant pneumothorax
- reasons to go in: wounds are deep; significant; pneumothorax persistent; or other intrathoracic conditions present
What is the mortality rate of thoracic trauma?
11-15.5% with extensive bite wound trauma
63% survival in cats
Pneumothorax
- Air may enter from thoracic wall, esophageal, or airway (lung, bronchus, or tracheal) penetration
- most common cause is thoracic wall penetration
- iatrogenic (ETT, centesis, ventilation)
- Pneumomediastinum may occur as a spontaneous event or secondary
- causes a restrictive breathing pattern with hypoventilation and diminished lung sounds.
- Tension pneumothorax: when a “flap valve” effect allows large amounts of air to enter, but not exit
- significant V/Q mismatch and decreased venous return
Dx
- Radiographic images should be made only upon patient stabilization
- 89% have bilateral pneumothorax and 31% have pulmonary bullae evident on thoracic radiographs.
List DDx for spontaneous pneumonthorax
- Bullae/blebs
- Emphysema
- Neoplasia
- Pleuritis
- Migrating plant material
- Pulm abscess
- Feline asthsma or inflammatory airway disease (most common cause in cats)
- Chronic pneumonia
- Heartworm, lungworm
Siberian Huskies overrepresented
What is the outcome of autologous blood patching for spontaneous pneumothorax?
Resolved pneumothorax in 7/8 dogs after 1-3 treatments (5-10ml/kg blood)
surgery
- Patient stabilization > thoracocentesis
- Open wounds resulting in pneumothorax should be covered immediately
- from thoracocentesis or blunt trauma > treated conservatively
- Thoracostomy tubes, Continuous suction for rapidly reaccumulate air or negative pressure cannot be achieved.
- Surgery is indicated > continued or repeated air accumulation within a 5-day period
- pleuraport
complications
- 17% of dogs
- recurrent pneumothorax,
- hemorrhage requiring reoperation
- aspiration pneumonia,
- sepsis
- minor incisional problems.
What is the recurrence rate and mortality rate of spontaneous pneumo in dogs treated conservatively vs surgically
Conservatively 50% recurrence, 53% mortality
Surgically 3% recurrence, 12% mortality
Chylothorax - Etiologies
casues:
- most common = idiopathic and is associated with thoracic lymphangiectasia.
- cardiomyopathy,
- mediastinal masses (e.g., lymphosarcoma, thymoma),
- dirofilariasis, blastomycosis,
- jugular vein or cranial vena cava thrombosis,
- diaphragmatic hernia,
- pericardial effusion,
- congenital anomalies
- blunt, iatrogeni, penetrating trauma
chylo - pathophysiology
- essentially a result of impaired or disrupted lymphatic drainage
- breeds may be predisposed.
- Blood work changes in affected animals are nonspecific
- chronic chylothorax may develop fibrosing pleuritis > fibrous tissue restricts pulmonary expansion
What do desquamated mesothelial cells make with chronic chylothorax?
Type III collagen promoting fibrosis and leading to fibrosing pleuritis
diagnosis- chylo
- complete workup (bloods, fluid testing, imaging including echocardiogram)
- modified transudate with protein concentrations >2.5 g/dL and nucleated cell count of 6000-7000/µL (lymphocytes and nondegenerate neutrophils)
- Triglyceride (increased) and cholesterol decreased
- Definitive diagnosis = lymphangiography CT
Popliteal Lymphangiography
- percutaneously with iohexol (1.5 mL of 300 mg I/mL solution in cats; 1 mL/kg in dogs) under ultrasound guidance
Intraoperative Intestinal Lymphangiography
- Administration of oil or cream per os hourly for 3 to 4 hours before anesthesia induction improves visualization of the lymphatics.
- abdomen is approached through a right paracostal incision
- ileocecal lymph node is located, and an efferent intestinal lymphatic is identified.
- methylene blue can be injected into the lymph node
- intraoperative fluoroscopy
- Postligation lymphangiography is used to confirm complete occlusion of all duct branches
What are the surgical options for chylothorax?
Thoracic duct occlusion/embolisation
Pericardiectomy
Cisterna chyli ablation
Omentalisation
thoracic duct trauma > may resolve < 1 week with thoracostomy tube
Thoracic Duct Occlusion
- 10th IC space on the right in dogs and left in cats
- transdiaphragmatic approach can also be use
- more easily identified after dye uptake (within 10 min)
- examined as far caudally in the chest as possible, where thoracic duct branches are likely to be fewest
- suture or hemovascular clips
- small lymphatic branches are found adherent to the aorta on the side contralateral
- En bloc ligation:: All structures in the area dorsal to the aorta and ventral to the sympathetic trunk
- Neither method results in a 100% success rate with regard to ligation of all branches > repeat lymphangiography after ligation
- left of the aorta most commonly missed, so transmediastinal entry
methylene > Heinz body hemolytic anemia and acute renal failure.
Thoracic Duct Embolization
- percutaneously or via an open laparotomy, with cyanoacrylate glue
- 1/2 dogs successful
- complications: distant, nontarget (e.g., pulmonary artery) embolization and persistent pleural effusion
Thoracoscopic Thoracic Duct Occlusion
- three ports in the caudal thorax (7th, 8th, 9th, 10th)
- Another port can be placed in the right cranial abdominal quadrant to permit methylene blue injection of a mesenteric lymph node
- clipped by means of a 10-mm medium to large clip applicator
- repositioned in dorsal recumbency for thoracoscopic pericardectomy
Pericardiectomy
- commonly performed concurrently with thoracic duct ligation to maximize the chance of success.
- combined success > prospective study with follow-up greater than 1 year reported a success rate of 55% in dogs
- Thoracoscopic pericardiectomy may be achieved with an intercostal or paraxiphoid approach.
- pericardial window can be created
- thoracoscopic pericardiectomy and thoracic duct ligation resulted in resolution of effusion in 86% of dogs with idiopathic chylothorax
Cisterna Chyli Ablation
- duct ligation with concurrent ablation cisterna chyli results in a success rate similar to that of thoracic duct ligation + pericardiectomy
- resolution was noted in 10 of 12 dogs in the cisterna chyli ablation group and 6 of 11 dogs in the pericardiectomy group
- cisterna chyli, which is medial to the hilus of the left kidney, via left paracostal incision
- kidney is mobilized and retracted medially to visualize the cisterna chyli on the surface of the aorta
- methylene blue to facilitate cisterna chyli identification
- cisterna chyli and any associated lymphatic connections to the caudal thoracic duct are sharply excised
- abdominal lymphatic drainage rerouted to major abdominal vessels, mesenteric root, or azygous vein
- single paracostal approach has been described > transdiaphragm (thoracic duct is dissected just cranial to the diaphragm)
sequele
- Five of the dogs that had resolution of chylothorax developed nonchylous pleural effusion within 3 to 6 weeks after surgery
- prednisone resolved 50%
omentalisation
- More frequently, it is used in combination
- omentum is mobilized and brought through the diaphragm
- pedicle is spread out and tacked dorsally and ventrally
- Theoretically, increased intrathoracic venous surface area provided by omentum may allow absorption of chyle or other fluid.
- unlikely that the omental lymphatics are important for resolution of effusion because they drain into the thoracic duct system, and no controlled prospective studies have been performed
WHat is the prognosis for idiopathic chylothorax?
- Thoracic duct attenuation alone: 50-59% dogs, 14-53% cats successful
- Thoracic duct and subphrenic pericardiectomy: 55-100% dogs, 80% cats
- Thoracoscopic duct ligation and pericardial window 83-86%
- Thoracic duct and cisterna chyli 63-88%
- Thoracic duct, percardiectomy and omentalisation 57-77%
difficult to compare because of small case numbers, variation in treatment protocols, regional or institutional differences in patient profiles and surgical techniques, limited follow-up times, lack of objective data on follow-up, and the retrospective nature of most studies.
What are the options for managing recurrent chylous effusion?
Percutaneous drainage systems (Pleuraport)
Pleuroperitoneal shunts
most common complication is port obstruction (pleuraport), severe abdominal distention, dislodgement, pyothorax, peritonitis, pleural compartmentalization, and lack of owner compliance.
infused with heparinized saline after aspiration
other Tx
- Decortication may result in serious hemorrhage and persistent air leakage
- Pleurodesis is defined as obliteration of the pleural space
Complications
persistent chylothorax,
persistent nonchylous pleural effusion,
lung lobe torsion
pneumothorax
Medical Management
- nutritional supplementation and a low-fat diet.
- rutin (50 to 100 mg/kg PO every 8 hours)
- Purported mechanisms of action include decreased lymphatic leakage, increased protein removal, increased macrophage phagocytosis, increased macrophage numbers, or increased proteolysis (not been proven in large clinical trials)
- repeated thoracocentesis may result in dehydration and loss of lipids, protein, and fat-soluble vitamins.
Pyothorax
- exudate protien greater than 3.5 g/dL and nucleated cell counts greater than 7000/µL. which are predominantly degenerate neutrophils.
- penetrating injuries to the thoracic wall, airways (e.g., inhaled migrating plant material), or esophagus; hematogenous spread; pulmonary or intrathoracic neoplasia or abscess; and extension
- postoperative complication in 6.5% of dogs undergoing thoracic surgery
- fungal and aerobic and anaerobic bacterial culture and antimicrobial sensitivity testing
- negative culture results may be obtained in up to 30%
- Frequently, multiple bacterial species are present, including anaerobes (60% of dogs and 89% of cats)
- Pasteurella spp. (22% of dogs, 62.5% of cats)
- Nocardia spp. (19% of dogs, 12.5% of cats)
- preoperative CT was recommended in patients undergoing surgical exploration.
treatment - pyo
Nonsurgical Treatment
- appropriate antimicrobial therapy, oxygen supplementation, crystalloid (fluid loss with drain)
- empirical ampicillin and enrofloxacin
- abs minimum of 6 to 8 weeks
- thoracostomy tube is placed unilaterally or, more commonly, bilaterally
- thorax is drained completely and then lavaged with warm, isotonic, crystalloid fluids (10 to 20 mL/kg) at least every 8 hours.
- Continued evaluation of packed cell volume, albumin, hydration status, and nutritional balance
- median duration for tube drainage of 4 to 8 days
surgery
- identification of a primary cause, failure of medical management, persistence of effusion beyond 3 to 7 days, and thoracostomy tube complications
- median sternotomy,
- A vessel-sealing device is useful for mediastinectom (haemorrgae diffuse with inflamed tissue)
- Thoracostomy tubes
What breed is predisposed to pyothorax?
lab
What is the prognosis of pyothorax?
medical vs Sx?
What factors are associated with increased survival in cats?
Successful Tx in 47.8 - 86%
85% disease free at 6m and 78% at 1yr post-op
disease free after medical and surgical treatment, respectively, were 32% and 85% at 6 months and 25% and 78% at 1 year
Factors assoc with increased survival in cats:
- Lower resp rate
- Higer heart rate
- Higher WBC counts
complications
- recurrence
- death,
- DIC,
- abdominal effusion
- thoracostomy tube complications
Malignant Pleural Effusion
- commonly caused by mesothelioma and carcinoma
- typically a modified transudate or sanguineous effusion
- Surgery is contraindicated in patients prediagnosed with mesothelioma, carcinomatosis, or lymphosarcoma.
- Neoplastic conditions associated with pleural effusion have a significantly shorter survival time (15 days) than those associated with inflammatory effusions (>785 days)
- Survival mesothelioma may be days to weeks, with rare reports of years of remission
thymoma
- dogs is thymoma (33% to 64%); in cats, thymic lymphoma is more common.
- Cranial vena cava syndrome
- significant local invasion, but rarely does the tumor spread to other thoracic or abdominal organs.
- RADS: mediastinal mass, pleural effusion, megaesophagus, or aspiration pneumonia.
- cystic areas identified on CT or ultrasonography
CT:
- differentiating mediastinal and pulmonary mass lesions and detecting tracheobronchial lymph node enlargemen
- accuracy is not 100%, Invasion of the cranial vena cava was noted on CT in 9 of 60 dogs (15%)
FNA
- Flow cytometry is useful for distinguishing thymoma and lymphosarcoma in dogs.
myasthenia gravis
- diagnosed in 17% of dogs with thymoma
- weakness or signs consistent with megaesophagus, acetylcholine receptor antibody titers should be evaluated
- caused by circulating autoantibodies against acetylcholine receptors, resulting in failure of nerve impulse transmission at neuromuscular junctions
- Tensilon/neostigmine test
old dogs and cats
ddx thymoma
osteosarcoma,
fibrosarcoma,
neuroendocrine tumor,
mesothelioma,
histiocytic sarcoma,
carcinoma
infectious granulomas, abcsess
lymphosarcoma,
branchial cyst,
heart-base tumors
Thymic lymphoma is a nonsurgical condition of the mediastinum that is most frequently diagnosed in younger animals.
What breeds are overrepresented with thymoma?
What paraneoplastic syndromes are common?
How many have concurrent nonthymic neoplasia?
Labs and Goldens
Myaesthenis gravis (up to 47%), hypercalcaemia
27% concurrent nonthymic neoplasia
How can you differentiate thymoma and lymphoma on cytology?
- Both contain large numbers of lymphocytes
- Thymoma will more consistently have epithelial cells which may also exfoliate mast cells, eosinophils and erythrocytes
surgery- thymoma
- myasthenia gravis: thymectomy itself may result in resolution of clinical signs
- usually via median sternotomy,
- Most commonly, the cranial vena cava is affected, followed by the internal thoracic arteries and axillary vein.
- Phrenic nerve involvement has also been documented > unilateral phrenic nerve transection occurred in 15 of 84 dog
- thoroscopy
outcome thymoma
complications
- aspiration pneumonia,
- hemorrhage,
- infection,
- hypocalcemia
- persistent signs of myasthenia gravis,
- DIC
- tumor recurrence (17%)
survival
- MST 1825 days in cats and 790 days in dogs.
- One- and 3-year survival rates were 89% and 74% in cats, respectively, and 73% and 49% in dogs
- Hypercalcemia and phrenic nerve transection was not correlated with survival rates
- Radiation therapy alone or in conjunction with surgery may be a viable means of prolonging survival
Anastomosis of the caudal thoracic duct and intercostal
vein using a microvascular anastomotic coupler device:
Experimental study in six dogs
Welker 2024
10th or 11th intercostal vein (ICV) using a microvascular
anastomotic coupler (MAC) device in dogs and assess patency of the anastomosis
on days 0 and 30.
Study design: Experimental study.
Sample population: Six adult Beagle dogs
operating microscope
The anastomosis was successful and lymphangiography documented
flow into the azygos vein in all six dogs immediately after surgery. At day
30, the anastomosis was patent in four of six dogs. In two dogs, flow through
the anastomosis was obstructed due to kinking of the ICV just cranial to
the MAC.
Conclusion from the abdominal lymphatics to the central venous circulation and thereby
preventing the stimulus for collateral circulation and persistent chylous effusion.
ability to perform this procedure in clinically affected
dogs remains unknown. Only lateral images were
obtained when performing the fluoroscopic lymphangiograms
and so it is possible that the ventrodorsal images
would have identified a different branching pattern than what was reported.
By
maintaining the flow of chyle from the abdominal lymphatics to the systemic
circulation, this procedure may reduce the stimulus for collateral circulation
and persistent flow to the cranial mediastinal lymphatics.
Current treatment options involve ligation of the TD and ablation of the cisterna chyli (CC) to eliminate flow through the TD and redirect it away from the thoracic lymphatics via acquired lymphaticovenous anastomoses created in the area of the CC ablation.
Treatment of idiopathic chylothorax with TD ligation and CC ablation is successful in approximately 80% of dogs.4–6
However, a potential mode of failure of TD ligation and CC ablation is the insufficient formation of lymphaticovenous anastomoses resulting in progressive hypertension within the abdominal lymphatic system.
This hypertension leads to the development of
collateral lymphatics that bypass the site of TD ligation and results in persistent leakage from the lymphatics in the cranial mediastinum.
Outcome of video-assisted thoracoscopic treatment of idiopathic chylothorax in 15 cats
Dickson 2024
cinti mayhew
Multi-institutional retrospective study.
Animals: Fifteen client-owned cats.
Thirteen cats underwent simultaneous
pericardectomy
Conversion from a thoracoscopic to open approach was necessary in 2/15 (13%)
postoperative complication was persistent pleural effusion in five cats (33%). Four of 15 cats (27%) died or were euthanized prior to hospital discharge
following surgery. Recurrence of effusion occurred in 1/7 (14%)
overall mortality attributed to chylothorax was 47%.
low incidence of intraoperative complications or conversion
Evaluation of mediastinoscopy for cranial mediastinal and
tracheobronchial lymphadenectomy in canine cadavers
Gibson 2024
mediastinoscopy was performed via a SILS port placed
cranial to the thoracic inlet with CO2 insufflation
retrieval or cup biopsy of a variety of lymph nodes is possible
from the described approach. Application in living animals and its associated
challenges should be further investigated.
Evaluation of thoracic duct ligation and unilateral
subphrenic pericardiectomy via a left fourth intercostal
approach in normal canine cadavers
Price 2024
Study design: Retrospective computed tomography (CT) review and cadaveric
study.
Animals: Thirteen dogs with idiopathic chylothorax and 10 canine cadavers
A review of lymphangiograms revealed a single TD in 10/13 clinical
cases at the fourth intercostal space.
Fewer thoracic duct branches at this location in comparison
with the standard caudal location may simplify TD ligation.
variable success rates,
ranging from 60–100% for open, and 85–95% for thoracoscopic
TD ligation and pericardiectomy
variable course and branching of the thoracic duct in
43 canine cadavers from the level of the cisterna chyli to
the level of the fourth thoracic intervertebral space, but anatomy of the duct cranial to the fourth intervertebral
space (the area of interest in the present study) could
not be well characterized
When contrast lymphangiograms are performed on
dogs with idiopathic chylothorax or experimentally
induced chylothorax, leakage or extravasation is seldom
reported.13,25–27 When abnormalities are noted, such as
dilated lymphatics or leakage of contrast, these abnormalities
are consistently identified cranial to the fourth intercostal
space in the mediastinum rather than from the
thoracic duct proper.
flow around the ligation site. These “bypass”
vessels were assumed to be due to “sleeping” lymphatics,
or small/collapsed lymphatics that were not evident on
preoperative lymphangiograms or at the time of surgery.
Median number of TD
branches at the level of the ninth and tenth intercostal spaces
were 3 (range:1–4), and 2 (range 1–4) branches,
Cranial to the proposed left fourth
intercostal surgical site the duct then emptied into cranial
mediastinal veins or ramified into numerous cranialmediastinal
lymphatic vessels and lymph nodes.
Bicavitary effusion in cats:
retrospective analysis of signalment,
clinical investigations, diagnosis and
outcome
Hardwick 2024
In total, 103 cats with bicavitary effusion were included. Neoplasia and cardiac disease were the most
common aetiologies of bicavitary effusion, in 21 (20.4%) and 20 (19.4%) cats, respectively, followed by infectious
disease (n = 11, 10.7%), trauma (n = 13, 12.6%), hypoalbuminaemia (n = 6, 5.8%), sterile inflammatory disease
(n = 4, 3.9%) and coagulopathy (n = 1, 1.0%).
median survival time for all cats with bicavitary effusion was
3 days
Physical examination and CT to
assess thoracic injury in 137 cats
presented to UK referral hospitals
after trauma
Nicola Mansbridge 2024
A multicentre, retrospective
In total, 137 cats
he most frequently identified thoracic pathologies on TCT were
atelectasis (34%), pulmonary contusions (33%), pneumothorax (29%) and pleural effusion (20%).
TCT may be useful in identifying cats with normal thoracic physical examination
findings that have significant thoracic pathology, and a high number of abnormal findings on thoracic examination
should raise suspicion for both minor and major thoracic pathology
Prognostic factors and outcome in cats with thymic epithelial tumours: 64 cases (1999-2021)
T. A. Marks 2024
TET = thymoma + thymic carcinoma
Sixty-four cats were included. Paraneoplastic syndromes were present in nine cats and metastatic disease was seen in two cat
Surgical excision was attempted in 54 cats with a perioperative mortality rate of 11%.
Surgical excision was attempted in 54 cats with a perioperative mortality rate of 11%.
Tumour recurrence occurred in 11 cats
Masaoka-Koga stage was the only significant prognostic factor detected on multi-variable analysis,
good long-term prognosis following surgery
represent the second most frequent tumour in this location in cats after lymphoma
Constrictive physiology is not present in all dogs
with idiopathic chylothorax
Taylor E. Adams 2024
monnet
12 client-owned dogs
diagnosis of constrictive physiology (CP) was established with cardiac catheterization and defined as elevated and equal diastolic pressures in all 4 cardiac chambers
8 dogs were entered into the CP group and underwent TDL and subtotal pericardectomy. Four dogs were entered in the NCP group and underwent only a TDL. Four dogs in the CP group and 1 in the NCP group required multiple surgeries for recurrent chylothorax. The 1-, 2-, and 3-year disease-free rates were, respectively, 100%, 100%, and 50% for the NCP group and 87.5%, 72.9%, and 72.9% for the CP group (P = .935). The 1-, 2-, and 3-year survival rates were, respectively, 100%, 100%, and 100% for the NCP group and 87.5%, 72.9%, and 72.9% for the CP group (P = .317).
CLINICAL RELEVANCE
Constrictive physiology should be evaluated by cardiac catheterization before surgical treatment of IC in dogs. If CP is not diagnosed, subtotal pericardectomy may not be required.
hypothesized that constrictive pericarditis was induced by the chronic chylothorax and a subtotal pericardectomy should be performed in combination with TDL in dogs with idiopathic chylothorax.
Steffey et al19 showed that fluorescence imaging with ICG and near-infrared light allows identification of all the branches of the thoracic duct at the time of surgery.
performing CT lymphangiogram after surgery to confirm ligation of the branches of the thoracic duct does not seem to be associated with an increased rate of long-term success or preventing recurrence, since other branches can open in the postoperative period
Computed tomographic lymphangiography via
intra-metatarsal pad injection is feasible in dogs
with chylothorax
Lee-Shuan Lin 2020
VRU
enhancement of thoracic ducts (TDs) was successful in 18 (90%)
dogs within 5-14 min after initiating the injection
successful enhancement of the lymphatic
vessels cranial to the popliteal lymph nodes was seen in all dogs within 5 min after injection. The
dose with good success to achieve TD enhancement was 1 mL/kg
The results of this study
highlight the limitations of radiography for differentiation of mediastinal and pulmonary masses
Resolution, recurrence, and chyle redistribution after thoracic duct ligation with or without pericardiectomy in dogs
with naturally occurring idiopathic chylothorax
Philipp D. Mayhew 2023
thorascopic
17 dogs underwent TDL, and 9 underwent TDL/P. Twenty-five of 26 (96%) survived the perioperative period. One dog died from ventricular fibrillation during pericardiectomy. Resolution rates for TDL and TDL/P were 94% and 88%, respectively (P = .55), with 1 late recurrence occurring in the TDL group in a median follow-up of 25 months (range, 4 to 60 months). On 3-month postoperative CT lymphangiography studies, ongoing chyle flow past the ligation site was demonstrated in 5 of 17 dogs, of which 1 dog developed recurrence at 13 months postoperatively. In 15 of 17 dogs, chylous redistribution after TDL was principally by retrograde flow to the lumbar lymphatic plexus
In dogs without evidence of CPP, TDL alone was associated with a very good prognosis for treatment of IC. In the absence of CPP, the additional benefit of pericardiectomy in the treatment of IC is questionable.
Outstanding questions that cannot be answered by the data include whether dogs with IC and evidence of CPP would have poorer outcomes if a TDL without pericardiectomy were performed. Further studies would be required to answer this question. A clear explanation for why a small percentage of dogs that appear to have a complete ligation at the time of TDL ligation collateralize also cannot be elucidated by the results of this study.
perineal subcutaneous injection
Surgical management of intrathoracic wooden skewers migrating from the stomach and duodenum in dogs: 11 cases (2014–2020)
S. Garcia-Pertierra 2022
A coeliotomy combined with transdiaphragmatic thoracotomy was performed in six of 11 cases (55%), a coeliotomy combined with median sternotomy in four of 11 cases (36%) and a median sternotomy alone was performed in one case. Foreign bodies penetrated from the stomach (n=10) or the duodenum (n=1). Intrathoracic trauma was most commonly identified to the lungs (n=3) and pericardium (n=3). Complications occurred in three of 11 cases (27%), two minor and one resulting in death. Ten of the 11 cases (91%) survived to discharge.
Laparoscopic extra-abdominal transfascial suturing
technique for diaphragmatic rupture repair in a cat
Filippo Cinti 2023
Prospective evaluation of lymphatic embolization as part of
the treatment in dogs with presumptive idiopathic
chylothorax
Jose L. Carvajal 2022
Eight client-owned dogs.
Methods: Dogs underwent CTLa followed by thoracic duct ligation (TDL),
pericardiectomy (PC) and LE. A mixture of 3:1 lipiodol: n-butyl cyanoacrylate
embolic solution was injected
LE was technically successful in six of the eight dogs; and clinically
successful in five of the six dogs
LE is feasible as part of treatment for dogs with IC. Additionally, a
robust lymphatic embolus and lack of radiocontrast flow past the embolus was
documented at 12 weeks following surgery.
Long-term survival in six cats
with mediastinal cysts
Corrine M Camero incidental findings
Radiographically, the cysts appeared as soft tissue opacities, u/s showed fluid
in one case the cyst ruptured during aspiration
Post-aspiration, all masses
were no longer visible with ultrasound or radiographs. No treatment was recommended for the cysts. Long-term
follow-up (2–9 years post-diagnosis) was available in all six cats. The cysts recurred in five cats but were never
associated with clinical signs.
CT findings, management and
short-term outcome of dogs with pyothorax: 101 cases (2010 - 2019)
A. Eiras-Diaz 2021
retrospective
CT abnormalities included pleural thickening (84.1%), pannus (67.3%), pneumothorax (61.4%), mediastinal effusion (28.7%), pulmonary (13.8%) and mediastinal (7.9%) abscessation, foreign body presence (7.9%), foreign body tracts (6.9%) and pneumonia (6.9%). Seventy-one percent of dogs were managed surgically, of which 90.2% survived, and 29% were managed medically, of which 72.4% survived.
Overall mortality was 14.8% and 86.6% of these dogs died within 48 hours of admission.
All dogs with evidence of a foreign body on CT underwent surgery
Mortality in our population was low and most dogs that died did so within 48 hours of hospitalisation, regardless of management type.
The majority of dogs were SIRS positive at presentation,
including all the non-survivors. This would suggest a high prevalence
of SIRS in canine pyothorax cases,
Short- and long-term outcome in cats diagnosed with pyothorax: 47 cases (2009-2018)
F. Krämer 2021
Fifty-five cats met the inclusion criteria. Eighty five percent (n=47) cats underwent medical management with thoracostomy tubes, pleural lavage and broad-spectrum antibiotics. Fifteen percent (n=5) cases failed medical treatment and underwent thoracotomy. Twenty eight percent (n=13) did not survive to hospital discharge. Short-term survival (14 days) was achieved in 72% (n=34). Long-term follow-up was available for 31 of 34 with a long-term survival rate of 68% (n=30). The recurrence rate was 6% (n=2).
C
o
nclusion: For cats with pyothorax that survive to discharge the prognosis is excellent and the condition is associated with a low recurrence rate.
Computed tomographic lymphangiography of the thoracic duct
by subcutaneous iohexol injection into the metatarsal region
Kitae Kim
The thoracic duct was visualized when at least 0.75 mL/kg of iohexol
was injected subcutaneously into the metatarsal region of dogs.
Efficacy of en bloc thoracic duct ligation in combination
with pericardiectomy by video-assisted thoracoscopic
surgery for canine idiopathic chylothorax
Hiroo Kanai 2020
To compare the outcomes of pericardiectomy performed with conventional
clipping thoracic duct ligation (C-TDL) to those with en bloc thoracic
duct ligation (EB-TDL) using video-assisted thoracoscopic surgery
(VATS) for canine idiopathic chylothorax.
Study design: Retrospective consecutive case series.
Animals: Thirteen
Long-term remission (LTR) was defined as rapid
resolution of pleural effusion and no recurrence for more than 1 year
Clinical improvement was achieved in 91.7% of the cases (C-TDL, 4/5;
EB-TDL, 7/7), excluding one case of intraoperative death. The LTR rate was significantly
higher with EB-TDL (6/7 [85.7%]) than with C-TDL (1/5 [20%])
The rates of thoracic ducts visualization by
postoperative CTLG were 100% (5/5) with C-TDL and 42.9% (3/7) with EB-TDL.
Conversion to an open thoracic
approach was not required in any of the dogs in this
case series
Evaluation of Jackson-Pratt Thoracostomy Drains
Compared with Traditional Trocar Type and
Guidewire-Inserted Thoracostomy Drains
Alec Sherman
jahaa
JP (n ¼ 31), TRO (n ¼ 25), and GW (n ¼ 9) thoracostomy drains were
placed in 65 patients. Ten minor (15.3%) and four major (6.2%) complications occurred. Cases with JP thoracostomy
drains were significantly less likely to have complications (2 minor, 1 major) than cases with TRO thoracostomy drains (8
minor, 3 major, P ¼ .009). There were no differences in the number of major complications when comparing all three drains
individually (P ¼ .350). JP drains and GW drains can be considered as an alternative to traditional TRO thoracostomy
drains.
Utility of bronchoscopy combined with surgery in the treatment and outcomes of dogs with intrathoracic disease secondary
to plant awn migration
Erin A. Gibson 2019
Conclusion: Migrating plant awns were successfully retrieved via bronchoscopy.
Agreement between CT findings and bronchoscopy was inconsistent, so there may be
roles for both modalities. Short- and long-term survival was excellent in this cohort.
Clinical significance: Bronchoscopy may allow for diagnostic and therapeutic advantages
compared with CT in dogs with endobronchial MPA. Actinomyces spp appear to
be variably present in surgically acquired bacterial cultures in dogs with MPA.
Computed
tomography was found to be unreliable for identifying MPA
Bronchoscopy was
successful in identifying and retrieving MPA in dogs and may
have preserved lung lobes from surgical removal (7 lobes preserved in this study)
Feasibility of open-chest cardiopulmonary resuscitation through
a transdiaphragmatic approach in dogs
Malcolm W. Jack 2019
To describe and evaluate the feasibility of a transdiaphragmatic (TD)
approach for open-chest cardiopulmonary resuscitation (OCCPR) as an alternative to
a traditional lateral thoracotomy (LT) in a canine cadaver model.
Study design: Randomized noninferiority ex vivo study.
Animals: Fourteen canine cadavers weighing 17.4–30.2 kg.
Conclusion: The TD approach did not prolong the procedure or increase the
complication rate compared with an LT.
Mayhew 2019 – VATS-TDL-P in 39 dogs with chylothorax
- mortality: 2/39 intra-op (1 euthanasia, 1 vfib during pericardectomy)
- intra-op complications: 9/39 (23%) - major: 2 lung laceration → VATS lung lobectomy
1 left auricle injury → stapled
1 air leak → conversion; 1 vfib → death
- conversion to open: 1/39 (3%) for TDL, 4/36 (11%) for pericardectomy
- resolution of effusion: 35/37 (95%) - late recurrence in 3/35 (9%) at 12, 12 and 19m
Treatment of idiopathic chylothorax in dogs and cats:
A systematic review
Lauren A. Reeves 2020
- no strong conclusions for effectiveness of surgical method
- some support for TDL+CCA or TDL+SP
- medical management not supported as primary treatment
- dogs: overall reoperation rate 23% - highest: TDL alone 46%; lowest: TDL+SP 12%
mortality rate: TDL+CCA, SP (1) alone 0% - cats: overall reoperation rate 7% - TDL alone → lowest rate (3%) vs SP alone 100% (2/2)
mortality rate: TDL alone/TDL+SP+CCA 57%, TDL+SP 13%
Korpita 2022 – u/s-guided intrahepatic indocyanine green or methylene blue injection
- NIRF lymphangiography → 5/5 TD visualisation vs 0/5 methylene blue
- intrahepatic ICG injection → successful NIRFL in median 6min, with 20min persistence
