Respiratory Flashcards
What value of pulmonary artery pressure is diagnostic for pulmonary hypertension when measured by right heart catheterisation?
≥25mmHg
What is the difference between pre-capilary and post-capillary pulmonary hypertension?
Background: PHT is an interplay between pulmonary blood flow, vascular resistance and pulmonary venous pressure.
Pre-capillary PHT is associated with an increase in pulmonary capillary wedge pressure ≥15mmHg
Pre-capilary PHT implies that there is pathology of the blood vessels themselves whereas pre-capillary suggests an increase in pressure that is not dependent on the vasaculature (e..g left-sided cardiac disease)
What value of tricuspic velocity implies pulmonary hypertesions?
≥3.4 m/s
What are the diagnostic criteria for low, intermediate and high risk of pulmonary hypertension?
Low = TR <3.0m/s with 0 - 1 sites of PHT
Medium =
- TR ≤ 3 with 2 sites of PHT
- TR 3.0 - 3.4 with 0 - 1 sites of PHT
- TR ≥3.4 with 0 sites of PHT
High:
- TR < 3.0 with 3 sites of PHT
- TR 3.0 - 3.4 with≥2 sites of PHT
- TR >3.4 with ≥1 sites of PHT
What are the echocardiographic sites of pulmonary hypertension and their signs?
Ventricals: flattening of the IVS, underfilling of the LV, RV hypertrophy, RV systolic dysfunction
Pulmonary Artery: Enlargement, Increased PR velocity, RPAD index < 30%, RV doppler acceleration time, systolic notching of the dopple RV outflow
RA and CVC: RA enlargement, enlargement of the caudal vena cava
What are the conditions that need to be pressent in order to diagnose PHT secondary to left-heart disease?
- Left atrial enlargement needs to be present as this indicates pulmonary artery wedge pressure being increased
- Demonstration of left heart disease (e.g. MMVD needs to be present)
What are the clinical findings suggestive of pulmonary hypertension?
Syncope
Respiratoy distress at rest
Activity or exercise terminatin in respiratory distress
Right-sided heart failure
+/- Tachypnoea at rest
+/- Increased respiratory effort at rest
+/- Prolonged post-exercise tachypnoea
+/- cyanotic or pale MM
Group 1 PHT
Pulmonary arterialhypertension
Group 2 PHT
Left heart disease
Group 3 PHT
Respiratory disease/hypoxia
Group 4 PHT
Thromboembolic disease
Group 5 PHT
Parasitic disease
Group 6
Multifactorial or unclear mechanisms
What are the thoracic imaging findings that suggest PHT (5 points)?
- Tortuous, blunted or dilated pulmonary arteries
- Asymettrical radiolucent lung fields
- Patchy or diffuse alveolar infiltrates
- Bulge in the pulmonary trunk
- Right sided cardiac enlargement
What are the CT findings that can suggest PHT (6 points)?
Pulmonary trunk to descenting aorta ratio >1.4
Evicdence of RA and RV enlargement
Decreased pulmonary vein to pulmonary artery ratio, increased RV to LV ratio
Presence of pulmonary arterial filling defects
Mosaic attentuation pattern on an inspiratory scan that does not go away with an expiratory phase
Perivascular patterns
What are the three groups of treatment for pulmonary hypertension?
Decrease risk of progression or complications from pulmonary hypertension
Target the underlying disease or factors contributing to pulmonary hypertension
Specific treatment of pulmonary hypertension
What strategies can be applied to mimise the risk of diease progression and complications from PHT (5 points)?
Exercise restriction
Prevent respiratory pathogens (vaccination and deworming)
Avoid pregnancy (may exacerbate PHT)
Avoid high altitude and air travel
Avoid non-essential procedures that require a GA
In which group of PHT disorders is sildenafil not reccomended?
Left heart disease since the cause is really post-capilary hypertension and in L>R shunting (can consider in R>L shunting). In both these scenarious increasing pulmonary blood flow can result in pulmonary oedema. However, it can be considered in LHD as long as CHF is not present and they have syncope thought to be due to PHT
When can the use of tPA be considered in cases of PHT?
In group 4 disease where RV dilation and systolic dysfunction, hypotension and collapse are all present (essentially there aren’t other options)
What condition can sildenafil be given in group 1 (pulmonary arteria hypertension)?
In hospital, due to the risk of pulmonary oedema development
What treatments, other than sildenafil, can be considerd in PHT but do not have sufficient evidence for or against?
Pimobendan
Milrinone (an IV PDE3 inhibitor)
rTKIs (inhibit the action of PDGF)
L-arginine (when combins with oxygen it forms NO)
How should patients wit pulmoanry hypertension be monitored?
- Clinical assessment:
- RR, Reff, RCHF
- At baseline, 2 weeks after starting therapy and q 3 - 6 month therafter - Echocardiography: at clinicians discretion
- Other:
- 6 minute walk tests
- Repeat thoracic imaging and pulse oximetry
What is the success rate of lateral wall resection compared to TECALBO?
40-55% success for LWR vs. 90% for TECALBO
What are the potential neurological complications of ear surgery?
Horners - more common in cats
Facial nerve paralysis
Vestibular signs
What is the genetic basis for congenital sensorioneural deafness in the following breeds?
a) Collies, Austrailian Shepherds, Shelties, Great Danes
b) Bull Terriers, Bulldogs, Great Pyrenees and Dalmatians
c) Dobermans
d) Cats
a) Dominant in merle variants
b) Autosomal recessive in piebalds
c) not stated
d) Autosomal dominant with incomplete penetrance
Categories of DDx for nasal disease
Stenosis
Foreign bodies
Oronasal communication
Rhinitis
Neoplasia
Non-malignant masses (e.g. fungal)
% of cases of chronic nasal discharge that are due to neoplasia?
30%
Identify the structures in this picture of a larynx
Which breeds are commonly affected by acquired laryngeal paralysis?
Labrador (most common)
Golden Retriever
St. Bernard
Newfoundland
Irish Setter
Brittany Spaniel
What are the main DDx for laryngeal paralysis?
- Congenital: genetic or laryngeal paralysis-polyneuropathy complex
- Trauma affecting the recurrent laryngeal nerve
- Neoplasia affecting the RLN (e.g. thymoma, lymphoma, thyroid carcinoma)
- Neuromuscular diseases: e.g. GOLPP
Which breeds suffer from:
a) Congenital laryngeal paralysis
b) Congenital laryngeal paralysis-polyneuropathy
a) Bouvier des Flandres, Huskeys and Malamutes, Bull Terriers, GSD
b) Dalmatians, Rottweilers, Leonburgers, Pyrenean Mountain Dogs
What structure should be considered in the evaluation of dogs with laryngeal paralysis?
Thoracic imaging to identify for evidence of megaoesophagus
Which is the best induction agent for allowing laryngeal motion when performing airway examination?
Thiopental
Which breed gets a concurrent laryngeal paralysis and laryngeal collapes syndrome?
Norwich Terriers
What are the three clinical stages of laryngeal collapse?
- Eversion of laryngeal saccules into the glottis
- Collapse of the cuneiform process into the laryngeal lumen
- Collapse of the carnuculate process causing complete airway obstruction
Treatment options for laryngeal collapse?
- Sacculectomy
- Relief of airway obstruction (e.g. BOAS surgery)
- Unilateral laryngoplasty
- Permanent tracheostomy
What are the main causes of laryngeal stenosis?
Bilateral ventriculochordectomy
Trauma or chronic inflammatory laryngeal disease
What is the normal inspiratory:expiratory ratio in small animals?
1:1 to 1:2 (inspiratory to expiratory)
How does stertor differ to stridor?
Stertor is a low pitched sound originating from the nasopharyngeal meatues whereas stridor is a high pitched sound originating from the larynx or trachea. It can worsen with exercise (in contrast to stertor)
What advanced imaging technique can be used to assess for pulmonary perfusion?
Tc 99 nuclear imaging
What is the minimum size required generally for a TTW?
15kg
What additional radiographic view may be helpful in diagnosing tracheal collapse?
Rostrocaudal veiw
Grades of tracheal collapse
Grade I: Tracheal membrane is slightly pendulous, cartilage maintains normal shape, and lumen size is reduced by 25%.
Grade II: Tracheal membrane is widened and pendulous, cartilage is partially flattened, and lumen size is reduced by 50%.
Grade III: Tracheal membrane is almost in contact with the ventral trachea, cartilage is nearly flat, and lumen size is reduced by 75%.
Grade IV: Tracheal membrane is lying on dorsal cartilage, cartilage is flattened and may invert, and lumen is essentially closed.
What are the medical treatment options for tracheal collapse?
Corticosteroids (systemic or inhaled)
Stonazalol
Anti-tussives (hydrocodone, butorphanol, codeine, diphenoxylate, maropitant)
Bronchodilators (theophylline, terbutaline, albuterol)
What are the surgical treatments for the following?
a) Intra-thoracic tracheal collapse
b) Cervical tracheal collapse
a) Intraluminal stents
b) Extraluminal rings (better prognosis)
What are the main tumour types encountered in the trachea?
Young dogs get osteochondroma
Older dogs: MCT, SCC, adenocarcinoma, osteosarcoma, extramedullary plasmacytoa, leiomyoma, fibrosarcoma