Respiratory Flashcards
What are the cut-offs for pulmonary arterial (PA) systolic and mean pressures that define pulmonary hypertension (PH)?
PA systolic > 30mmHg, PA mean >20mmHg
List the 5 disease classes which can lead to pulmonary hypertension.
ACVIM consensus
Group 1 (pulmonary arterial hypertension) – primary diseases of the vasculature. E.g. idiopathic, familial, drugs/toxins, congenital heart disease (systemic-to-pulmonary shunts), HWD, veno-occlusive disease, persistent PH of newborns.
Group 2 (pulmonary venous hypertension) – left-sided heart disease & chronic increases in LA pressure. Valvular or myocardial dz. MOST COMMON in dogs.
Group 3 (PH associated with lung diseases or hypoxemia) – obstructive pulmonary disease, interstitial lung disease, alveolar hypoventilation, sleep apnea, chronic exposure to high altitude, developmental abnormalities.
Group 4 (PH associated with chronic thrombotic or embolic) – obstruction of proximal or distal PAs, non-thrombotic embolism (HWD or other parasites, neoplasia, foreign material – catheter or coil)
Group 5 (systemic & other disorders) – compression of pulmonary vessels, lymphadenopathy, neoplasia, fibrosing mediastinitis, granulomatous disease, others (histiocytosis, sarcoidosis, lymphangiomatosis)
Bronchial collapse occurs most commonly in which regions?
L cranial & R middle bronchi
Bronchial collapse occurs most commonly in which regions?
L cranial & R middle bronchi
Thoracic radiographs most sensitive for the diagnosis of airway collapse in which regions of the lungs?
Sn for the detection of bronchoscopically identified collapse was highest for radiography at the trachea, left lobar bronchi & right middle bronchus. But relatively low Sp.
What clinical sign can epiglottic entrapment of the soft palate cause?
Reverse sneezing
How to calculate estimated systolic PA pressure from echo?
Measure TRV max
Modified Bernoulli equation:
Pressure gradient (aka estimated systolic PAP) = 4 x (TRVmax)^2 in mmHg
ACVIM consensus panel’s definition (cut-offs) for pulmonary hypertension in dogs?
TR PG cut-off of >46 mmHg (TRVmax >3.4 m/s)
Defined as moderate PH historically
Specific treatment for PH targets which 3 pathways?
ACVIM consensus.
NO, endothelin & prostacyclin pathways
These mediate pulmonary arterial/arteriolar vasoconstriction (secondary to endothelial injury).
What is a rare disease to be suspected if a dog with pulmonary hypertension develops pulmonary oedema after sildanefil treatment? How does this occur?
ACVIM consensus
Pulmonary veno-occlusive disease or pulmonary capillary hemangiomatosis.
Also caution when administering PDE5-i in dogs with LHD & congenital shunts.
Reactive” or “responsive” pulmonary arteries (or arterioles) have an unpredictable response to tx. Increased right sided CO, acutely increases pulmonary VR to the LA»_space; subsequently increase LA & thus pulmonary venous and capillary pressures»_space; pulmonary oedema.
What anti-neoplastic drug may be considered as an adjunct treatment for refractory PH in dogs & MOA? What evidence is there to support its efficacy?
ACVIM consensus
TKIs (e.g. toceranib, imatinib) - cause PA vasodilation by inhibiting action of PDGF (by inhibiting phosphorylation of PDGF-receptor TK). Used in people, little data in dogs, but imatinib reduced PAP in dogs with PH 2’ to LHD in 1 study.
List the broad clinical signs of respiratory disease in dogs and cats
- Sneezing
- Reverse sneezing
- Nasal discharge
- Open mouth / postural breathing
- Audible respiratory sounds
- Stridor
- Stertor
- Wheezes?
- Crackles?
- Coughing
List the various abnormal respiratory sounds and describe how they help localise respiratory disease
- Stertor - soft palate / nasopharynx
- Stridor - inspiratory noise, continuous - larynx
- Wheeze
- low pitched versus high pitched
- large airway versus small airway
- Monophonic versus polyphonic
- large airways vs smaller/multiple airways
- low pitched versus high pitched
- Crackles
- Loudest end inspiratory
- Indicate alveolar or bronchiolar disease
- Decrease / absent sounds
- Pleural space
- Dorsally reduced sounds - air
- Ventral reduced sounds - fluid
- Pleural space
List the various imaging modalities to assess the respiratory tract.
Together with their major indication and limitation
- Radiography
- General assessment of heart size and lung/airway changes. Assess symmetry of the nose.
- Nasal studies limited by complexity of the structure and difficulty identifying early lesions
- Computed tomography
- Indicated for nasal and thoracic imaging - Ideal for thoracic studies due to spatial definition, contrast and speed of acquisition
- The need for sedation / general anaesthesia is the biggest limitation in thoracic investigations
- MRI
- Primarily indicated for assessment of nasal disease and other fixed soft tissue changes
- Thoracic investigation limited by movement and bony change may be underestimated
- Fluoroscopy
- Dynamic airway disease and swallowing studies (pharyngeal and oesophageal function)
- Limited by patient compliance primarily
- Ultrasonography
- Assessment of extra-luminal soft tissue structures. Descriptions of changes have been reported for laryngeal paralysis (insensitive for laryngeal collapse)
- Limited by tissue/air interface and tissue/bone interface artefacts
- Nuclear Imaging
- Global assessment of lung perfusion and lung ventilation (IV versus nebulized technetium) including V/Q scans
- Most sensitive for identifying PTE
- CAn be used for assessment of mucocilliary clearance
- Cumbersome and requires patient isolation
- Poor spatial resolution
List the options for sampling of the respiratory tract
Nose, large airways and lower airways
- Nasal swab
- Nasal flush
- Nasal biopsy
- Transtracheal wash
- Bronchial brushing
- Bronchoalveolar lavage
- Transthoracic needle aspirate or biopsy
- Surgical biopsy