Chapter 105 Thoracic Cavity Flashcards
What is normal pleura fluid volume in dogs? and in cats?
- 1 ml/kg in dogs
- 3 ml/kg in cats
What side does the thoracic duct run on in dogs and cats? Where does it cross to contralateral side in dogs?
Runs along left in cats.
Runs along right in dogs, crossed to left at level of 5/6th vertebra.
Thoracic duct is drainage for most of body except what? Where does this region drain into instead?
Right thoracic limb, shoulder and cervical region drain into right lymphatic duct.
Where does the cisterna chyli live?
Dorsal to the aorta (and l in dogs), caudal to level of celiac and cranial mesenteric arteries, level with 1-4th lumbar vertebrae (usually 3rd in dogs)
Where does the thoracic duct terminate (i.e. drain into?)
L jugular or jugulosubclavian angle
Until what age does thymus keep growing?
4-5 months
What is seen histologically in a normal thymus (two features)
- Small lymphocytes (same as those foudn elsewhere)
- Spherical/oval corpuscles Hassall bodies (concentrically arranged cells with central degenerated cells)
What is the mean peak inspiratory and end expiratory pleural pressure in awake dogs?
Inspiratory -26 cm H2O
Expiratory -15 cm H2O
What is functional residual capacity?
FCR = volume of air remaining at end of normal exhilation (approx 45 ml/kg). Point at which forces of lung and chest wall are equal and opposite
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What is the net movement of fluid across parietal and visceral pleura?
Overall, fluid moves out of parietal pleura, and in to visceral pleura
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What is the main function of the thymus?
Maturation and selection of T-cells
(+ endocrine funtion suggested)
What are the TP, SG and TNCC (ug/L) values to classify an exudate, modified transudate and transudate?
List the 6 “clinically useful” classifications of pleural effusion (and 2 obscure ones)
Sanguineous, serosanguinous, inflammatory, chylous, transudate, neoplastic
Bilithorax and urothorax
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how can CHF vs other feline pleural effusion be distinguished?
NT-proBNP in fluid >in cardiogenic effusion (1100 vs 100 pmol/L)
How is chylous effusion diagnosed (3 options)?
- Effusion triglycerides > serum triglycerides and fffusion cholesterol < serum cholesterol (N.B. cholesterol effusion not related to lymphatics - usually due to chronic effusion in humans. Cholesterol effusion not reported in dogs/cats)
- Presence of chylomicrons (stain with Sudan Black)
- Positive ether clearance test
- (on cyto lymphocytes usually predominate but may be taken over by degenerate neuts if chronic)
List 5 ddx for non-septic inflammatory pleural effusion
- Hepatitis
- Pancreatitis
- Diaphragmatic hernia
- FIP
- LLT
- Neoplasia
- Chronic chylothorax
What is typical TP and SG values for FIP effusion?
TP 5-12 g/dL
SG >1.017
Up to what volume of air (pneumothorax) has been shown not to cause clinical signs in dogs
45 ml/kg
What are the lower volume limits for radiographic detection of pleural fluid indogs? and in cats?
100 ml in dogs and 50 ml in cats
List 3 radiographic features of pleural effusion
- Pleural fissure lines
- Retracion of lung borders from chest wall
- Effacement of cardiac silhouette and diaphragm (loss of detail)
What % of CT guided FNAs, and of CT guided biopsies (of intrathoracic lesions) were diagnostic?
What is % of heamorrhage and % pneumothorax (n.b. most require no tx)
FNA 65%
Biopsy 83%
30% haemorrhage
27% pneumothorax
In ECVS exam style, what tests shoudl be run on effusion?
If suspect pancreatitis?
Differentiating transudate vs exudate in cats?
Differentiating transudate vs exudate in dogs?
- Cytology
- PCV
- TP, SG, TNCC
- Aureobic, anaerobic, fungal culture and susceptibiltiy
- Triglycerides and cholesterol
- Can run lipase and amylase if suspect panc.
- Differentiating transudate vs exudate in cats? Effusion:serum TP ratio and effusion [lactate dehydrogenase]
- Differentiating transudate vs exudate in dogs? [Effusion CRP]. (VEGF not useful for malignant vs non malignant)
At what level shoudl thoracostomy tube be inserted?
7-9th rib
What is recommended inspiratory:expiratory ratio during mechanical ventilation? why?
1:2 - 1:3, because mechanical ventilation –> increased pleural pressures (3-5 cm H2O) –> reduced venous return, pukmonary and coronary circulation.
2 recommendations re securing thoracostomy tube, specific to finger trap suture
gapt between throws at leastas wide as tube, and at least 6 crossings.
(x-ray after if not placed surgically)
what are recommended fluids levels for removal of thoracostomy tube?
previsouly 2 ml/kg/day
paper showed in dogs usually 3 ml/kg/day, cats 5 ml/kg/day
list typical ‘dose; of intrapleural bupi and lidocaine and fentanyl CRIs
Intrapleural bupi 1.5mg/kg q6 hours
Fentanyl 1-5 mcg/kg/hr
Lidocaine 20-50 mcg/kg/min
In animals undergoing thoracotomy, what was overall mortality rate? Loist 5 factors associated with non-survival
5.9% mortality
Pre-op oxygen requirement, use of NM blockade, surgical duration (>180m), blood product requirement (not ASA status)
List 4 most common thoracic findings in bite wounds
Rib fractures > pneumothorax > contusions > pleural effusion
In cats with high rise syndrome, what % have pneumthorax? and haemotorax?
20 - 60% pneumothorax, 10% haemothorax
What 3 factors have been associated with non-survival in cats with thoracic trauma?
Flail chest, pleural effusion, diaphragmatic hernia
Mortality rate for thoracic bite wounds?
11-15%
What are possible causes of spontaneous pneumothorax, in order of prevalence?
What breed over-represened for spontaneous pneumothorax?
Bullae/blebs/pulmonary emphysema (68% dogs) vs asthma in cats
Neoplasia (11% dogs, 14% cats)
pleuritis, migrating plant material, pulm abcessation, chronic pneumonia. heartworm.lungworm
Huskies over-represented
- In Howes 2020 JSAP, what was 2 and 5 year survival rate for dogs undergoing sx for spontaneous pneumothorax?
- What was recurrence rate?
- What were risk factors for recurrence (univariable)
- In tobias, what was recurrence rate and mortality rate for medically managed dogs?
Howes:
- 88% 2 year survival, 84% 5 year survival
- 14% recurrence rate
- Giant breed and increased BW risk factors
Tobias:
Recurrence rate 50%, mortality rate 53%
List 5 ddx for underlying cause of chylothorax. What is most common cause?
- Neoplasia (mediastinal masses)
- Cardiomyopathy
- Congenital abnormalities ( tetalogy, PPDH, tricuspid dysplasia, cor triatriatum dexter, DCRV, thoracic duct anomaly)
- Cranial caval/jugular compression/thrombosis
- Diaphragmatic hernia
- Pericardial effusion
- LLT
- Trauma to thoracic duct
- Heart worm
- IDIOPATHIC MOST COMMON
What dog breed and cat breed are predisposed to chylothorax?
Afghan hound and oriental cats
Briefly outline pathophys of fibrosing pleuritis secondary to chylothorax
Outline how to perform popliteal lymphangiography
How is intestinal lymphagiography performed
Give oil/cream 3-4 hours pre-op.
Mesenteric lymphatic vessel or iliocolin LN.
Can use methylene blue to aid visualisation (max 0.5 mlkg)
What is pathophysiological rationale behind pericardiectomy for chylothorax?
Decreases r heart and venous pressures –> eased flow + formation of lymphaticovenous anastomoses
What are anatomical ventral and dorsal limits of thoracic duct ligation
Ventral limit = dorsal aorta
Dorsal limit = sympathetic trunk (i.e. can include azygous v if nec.)
- How long does it take for methylene blue colourisation to appear in the thoracic ducat after iliocolin LN injection?
- How long does it persist for?
- What are risks of methylene blue use?
- 10 minutes to appear
- Persists 60 mins
- Complication of methylene = heinz body anaemia (oxidative) and renal damage.
List 3 (broad) methods of thoracic duct ligation
Open sx liation
Thoracoscopic ligation
Cyanoacrylate embolisation (reported in 2 cases of recurrent chylothorax that already had TD ligation and pericardiectomy)
List 5 possible sx interventions for chylothorax resolution
And options for ‘management’ of recurrent effusions
Initial sx
- TD ligation
- Pericardiectomy
- Cisterna chyli ablation
- Omentalisation
- Pleurodesis (not proven useful in dogs)
Recurrent effusion management
- Re-analyse fluid
- Repeat lymphangiography
- Try above options not done at initial sx
- Per-cutaneous drainage (Pleural port)
- Pleural-peritoneal drainage (owner pump operated 1 way valve = active shunt, or mesh in diaphargmatic defect = passive shunt)
What medication can be given for chylothorax (unproved). What is proposed MoA?
Rutin 50-100mg po tid.
MoA: decreased lymphatic leakage, increased protein removal, increased macrophage phagocytosis, increased macrophage numbers, increased proteolysis
What is resolution rate of chylothorax following TD ligation + subtotal pericardiectomy in dogs? and cats?
Dogs 55-100%
Cats 80%
(sl lower if just TD ligation + cisterna chyli)
What two bacteria are associated with sulphur granules?
How do they look on cytology?
Actinomyces or Nocardia
Gram positive, acid fast, filamentous rods
What proportion of dogs have polymicrobial pyothorax?
and cats
60% dogs
89% cats
What was survivaly to discharge % in dogs with pyothorax who underwent
Thoracocentesis only
Thoracostomy (+- lavage)
Surgery
Thoracocentesis only: 29%
Thoracostomy (+- lavage): 77%
Surgery: 92%
What is most common thymic mass in dogs?
And cats?
Dogs thymoma
Cats lymphoma
How can thymoma be distinguished from lymphome following FNA
Flow cytometry. If >10% of lymohocytes have dual expression of CD4 and CD8 is consistent with thymoma
List 2 paraneoplastic syndromes with thymoma
Myasthenia gravis
Hypercalcaemia
Also: polymyositis, myocarditis, feline exfoliative dermatitis,
What proportion of dogs with thymoma have myasthenia gravis?
17%
How is myasthenia gravis diagnosed
acetylcholine–receptor antibody titre
Tensilon test (endrophonium chloride - risk parasymathetic ‘crisis’ have atropine on hand)
What is MST following thymoma excision in dogs?
And cats?
What factors have been negatively associated with survival?
Dogs: 2 years
Cats: 6 years
Higher grade (3), tumour elsewhere, megaoesophagus and concurrent pneumonia
List methods for performing lymphangiography for chylothorax
Contrast injection into:
- Popliteal LN
- SC metetarsal region (Kim VetSurg 2020)
- Mesenteric LN (or lacteal vessel) (intra-op or US guided pre-op)
- Rectal/vaginal mucosa or perianal SC tissues
Intra-op can also inject NMB to aid visualisation (or indocyanine green + near infra-red flouresence (Steffey VetSurg 2018)