Ch 105 Throacic cavity Flashcards
(103 cards)
1
Q
Anatomy
A
- 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
2
Q
what is normal plural fluid volume in dogs and cats?
A
Dog - 0.1ml/kg
Cats: 0.3ml/kg
3
Q
What cells make up normal plueral fluid?
A
mesothelial cells 9-30%
Monocytes/macrophages 61-77%
Lymphocytes 7-11%
Neutrophils under 2%
1500-2500 cells/mcL
Protein less than 2.5g/dL
4
Q
Lymph Nodes
A
- 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
5
Q
What % of dogs have a dorsal thoracic lymph centre?
A
25%
6
Q
Thoracic Duct
A
- 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
7
Q
Which parts of the body are NOT drained by the thoracic duct?
A
Right thoracic limb
Right shoulder
Cervical regions
Drained by the right lymphatic duct
8
Q
What is the cisterna chyli and where is it located?
A
- 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
9
Q
What is the major difference in the thoracic duct anatomy in dogs and cats?
A
Dogs - travel on right sife through caudal thorax, dorsolateral to aorta. Crosses to left at T5/6
Cats: On the left!
10
Q
Where does the thoracic duct drain?
A
Left external jugular vein or jugulosubclavian vein
(Significant anatomical variation - some branches may terminate in azygous)
11
Q
What embryonic structure forms the thymus?
At what age does it stop growing and starts to involute?
A
- 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.
12
Q
What is the normal functional residual capacity (volume of air remaining in lung at end of expiration)
A
45ml/kg
represents the point at which all forces, including collapse of the lungs and expansion of the chest cavity, are in passive equilibrium
13
Q
What fluid dynamics favour pleural fluid production and absorption?
A
- 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
14
Q
Respiration
A
- 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
15
Q
Fluid Gradients (pleural fluid)
A
- 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.
16
Q
What are the functions of the thymus?
A
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
17
Q
pathophysiology
A
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.
18
Q
How do you classify pleural transudate, modified transudate and exudate?
A
19
Q
List causes of a pleural transudate
A
Hypoproteinaemia
Increased hydrostatic pressure as with CHF (NT-proBNP significantly higher in cats with effusion from heart disease)
20
Q
ist DDx for a serosanguinous (modified transudate) effusion (6)
A
Lung lobe torsion
D-hernia with liver entrapment
Pericardial effusion
Right sided heart failure
Neoplasia (diffuse mesothelioma or carcinomatosis)
Idiopathic pleuritis
21
Q
List DDx for a sanguinous effusion
A
Trauma
Coagulopathy
Acute lung lobe torsion
Iatrogenic
Tumours (chemodectoma, right atrial HSA)
22
Q
List DDx for chylous effusion
A
Any condition that increases hydrostatic pressure in the cranial vena cava
Trauma
Idiopathic
23
Q
How do you confirm chylothorax?
A
- 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
24
Q
List DDx for inflammatory effusion
modified transudates or exudatesmodified transudates or exudates
A
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
25
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
26
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
27
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
28
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
29
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
30
What ICS is used for thoracocentesis?
7-9th
31
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
32
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
33
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
34
In which ICS is a thoracostomy tube placed?
7th or 8th
35
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
36
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
37
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
38
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
39
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.
40
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
41
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,
42
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.
43
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
44
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
45
What is the mortality rate of thoracic trauma?
11-15.5% with extensive bite wound trauma
63% survival in cats
46
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.
47
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
48
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)
49
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.
50
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
51
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
52
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
53
What do desquamated mesothelial cells make with chronic chylothorax?
Type III collagen promoting fibrosis and leading to fibrosing pleuritis
54
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
55
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
56
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)
- Steffey 2018 > fluorescence imaging with ICG and near-infrared light allows identification of all the branches of the thoracic duct at the time of surgery.
- 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.
57
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
58
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
59
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
- Pericardiectomy decreases right heart and venous pressures, easing flow across and enhancing formation of lymphaticovenous anastomoses.
- 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
60
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%
61
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
62
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.*
63
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
64
other Tx
- Decortication may result in serious hemorrhage and persistent air leakage
- Pleurodesis is defined as obliteration of the pleural space
65
Complications
persistent chylothorax,
persistent nonchylous pleural effusion,
lung lobe torsion
pneumothorax
66
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.
67
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.
68
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
69
What breed is predisposed to pyothorax?
lab
70
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
71
complications
- recurrence
- death,
- DIC,
- abdominal effusion
- thoracostomy tube complications
72
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
73
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
74
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.*
75
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
76
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
77
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
78
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
79
Anastomosis of the caudal thoracic duct and intercostal
vein using a microvascular anastomotic coupler device:
Experimental study in six dogs
Welker 2024
Anastomosis caudal thoracic duct and intercostal vein using microvascular anastomotic coupler: Experimental six dogs
10th or 11th intercostal vein (ICV) with operating microscope.
Anastomosis successful in all six dogs > lymphangiography documented flow into the azygos vein post surgery.
D 30, patent 4/6. In two dogs, obstructed due to kinking of the ICV just cranial to the MAC.
Diverted flow of abdominal lymphatics to the central venous circulation and thereby preventing the stimulus for collateral circulation and persistent chylous effusion.
in clinically affected > remains unknown.
Only lateral images fluoroscopic lymphangiograms > could not rule out branches in VD
80
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.
81
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
82
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.
83
Evaluation of thoracic duct ligation and unilateral
subphrenic pericardiectomy via a left fourth intercostal
approach in normal canine cadavers
Price 2024
Retrospective (CT) review and thoracic duct ligation and unilateral subphrenic pericardiectomy via a left 4th ICS. cadavers
CT lymphangiograms review: single TD in 10/13 at 4th ICS > Fewer branches in comparison to standard caudal location (1-4 branches at 9/10th ICS)
STUDY: thoracic duct in 43 canine cadavers from cisterna chyli to
the level of the fourth thoracic intervertebral space variable branches and course
contrast lymphangiograms > leakage or extravasation is seldom
reported.
flow around the ligation site > “bypass” vessels were assumed to be due to “sleeping” lymphatics not evident preop or at Sx
Cranial to the proposed left fourth > ramified into numerous cranialmediastinal lymphatic vessels and lymph nodes.
84
Bicavitary effusion in cats:
retrospective analysis of signalment,
clinical investigations, diagnosis and
outcome
Hardwick 2024
Bicavitary effusion in cats: retrospective 103 cats.
Neoplasia 20% and cardiac disease 20% > most common aetiologies of followed by infectious 10.7%, trauma (12.6%) etc
MST with bicavitary effusion = 3 days
85
Physical examination and CT to
assess thoracic injury in 137 cats
presented to UK referral hospitals
after trauma
Nicola Mansbridge 2024
Retrospective, examination and CT of thoracic injury in 137 cats
CT: atelectasis (34%), pulmonary contusions (33%), pneumothorax (29%) and pleural effusion (20%).
CT may be useful in identifying cats with normal thoracic physical examination
86
Prognostic factors and outcome in cats with thymic epithelial tumours: 64 cases (1999-2021)
T. A. Marks 2024
| TET = thymoma + thymic carcinoma
Retrospective. cats with thymic epithelial tumours: 64 cases
TET = thymoma + thymic carcinoma
Paraneoplastic syndromes 9 cats and metastatic 2 cats
Surgical > 54 cats, mortality 11%.
Tumour recurrence 20%
Masaoka-Koga stage was the only significant prognostic factor (1366d vs 454d)
good long-term prognosis following surgery > MST surviving discharge 897 days
87
Constrictive physiology is not present in all dogs
with idiopathic chylothorax
Taylor E. Adams 2024
| monnet
Retrospective. Constrictive physiology is not present in all dogs with idiopathic chylothorax. 12 cases
Dx constrictive physiology (CP) > cardiac catheterization = elevated and equal diastolic pressures in all 4 cardiac chambers
8 CP group > TDL and subtotal pericardectomy. 4 NCP group > only a TDL.
50% CP group and 1 NCP group required multiple surgeries for recurrent chylothorax.
1-, 2-, and 3-year disease-free rates (Survival rates similar):
- 100%, 100%, and 50% NCP
- 87.5%, 72.9%, and 72.9% CP group (not significant difference)
If CP is not diagnosed, subtotal pericardectomy may not be required. (constrictive pericarditis induced by the chronic chylothorax)
CT lymphangiogram post sx > not associated with an increased rate of long-term success as branches can open in the postoperative period
88
Computed tomographic lymphangiography via
intra-metatarsal pad injection is feasible in dogs
with chylothorax
Lee-Shuan Lin 2020
| VRU
CT lymphangiography via intra-metatarsal pad injection in dogs with chylothorax
enhancement of thoracic ducts (TDs) was successful in 18 (90%) 5-14 min after injection
dose = 1 mL/kg
89
The results of this study
highlight the limitations of radiography for differentiation of mediastinal and pulmonary masses
90
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
Retrospective. Thorascopic thoracic duct ligation with or without pericardiectomy . 17 TDL, and 9 TDL/P.
(96%) survived the perioperative period. 1 died > VF during pericardiectomy.
Resolution rates: TDL 94% and TDL/P 88% (not significant)
1 late recurrence TDL group
3-month postop CT: flow past the ligation site in 5/17 41% > only 1 dog developed recurrence
15/ 17 dogs, chylous redistribution > retrograde flow to the lumbar lymphatic plexus
In dogs with no CPP, TDL alone > very good prognosis. The additional benefit of pericardiectomy is questionable.
Would dogs with IC and CPP have poorer outcomes if a TDL without pericardiectomy performed? Why some after TDL ligation collateralize and others don’t? unknown answers.
| perineal subcutaneous injection
91
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.
92
Prospective evaluation of lymphatic embolization as part of
the treatment in dogs with presumptive idiopathic
chylothorax
Jose L. Carvajal 2022
Prospective. lymphatic embolization for idiopathic chylothorax. 8 dogs.
Methods: thoracic duct ligation (TDL), pericardiectomy (PC) and LE.
A mixture of 3:1 lipiodol: cyanoacrylate
LE technically successful 6/7; and clinically successful 5/6
lack of radiocontrast flow past the embolus documented at 12post op
92
Long-term survival in six cats
with mediastinal cysts
Corrine M Camero 2019
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.
93
CT findings, management and
short-term outcome of dogs with pyothorax: 101 cases (2010 - 2019)
A. Eiras-Diaz 2021
Retrospective. outcome of dogs with pyothorax: 101
CT: pleural thickening (84.1%), pannus (67.3%), pneumothorax (61.4%), mediastinal effusion (28.7%), abscessation, foreign body
71% managed surgically > 90.2% survived
29% managed medically > 72.4% survived.
Overall mortality 14.8% > most dies within 48 hours of admission.
The majority of dogs were SIRS positive at presentation > high prevalence in canine pyothorax cases
94
Short- and long-term outcome in cats diagnosed with pyothorax: 47 cases (2009-2018)
F. Krämer 2021
Retrospective. cats diagnosed with pyothorax: 47
(n=47) cats underwent medical management with thoracostomy tubes, pleural lavage and broad-spectrum antibiotics.
15% failed medical > thoracotomy.
28% did not survive to hospital discharge.
Short-term survival 72%. Long-term survival rate of 68% (n=30).
recurrence 6%
cats survive to discharge the prognosis is excellent
95
Computed tomographic lymphangiography of the thoracic duct
by subcutaneous iohexol injection into the metatarsal region
Kitae Kim 2020
The thoracic duct was visualized when at least 0.75 mL/kg of iohexol
was injected subcutaneously into the metatarsal region of dogs.
96
Efficacy of en bloc thoracic duct ligation in combination
with pericardiectomy by video-assisted thoracoscopic
surgery for canine idiopathic chylothorax
Hiroo Kanai 2020
Retrospective. Efficacy of en bloc thoracic duct ligation vs conventional ligation in combination with pericardiectomy by video-assisted thoracoscopic. 13 cases.
Long-term remission = no recurrence > 1 year
Clinical improvement 91.7%
one case of intraoperative death.
remission rate significantly higher with en bloc [85.7%]) vs conventional [20%])
thoracic ducts visualization by postoperative CTLG >100% conventional TDL and 42.9% en bloc
Conversion to an open thoracic approach was not required
97
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.
98
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
bronchoscopy with surgery for plant awn migration
Migrating plant awns were successfully retrieved via bronchoscopy.
Agreement CT and bronchoscopy was inconsistent > roles for both modalities.
Short- and long-term survival was excellent in this cohort.
Bronchoscopy may allow for diagnostic and therapeutic advantages > may have preserved lung lobes from surgical removal (7 in this study)
CT found to be unreliable for identifying MPA
99
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.
100
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
101
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%
102
Korpita 2022
– Prospective. Experimental. Thoracoscopic detection
– 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
