Respiratory Flashcards
What is the difference between stertor and stridor?
Stertor: noise absent with mouth open and discontinous. low pitched. Nasal or nasopharyngeal obstruction - inspiratory but occasionally exp as well.
Stridor: continous, high-pitched, noise present with mouth open or closed. Laryngeal or laryngopharyngeal obstruction.
Where can a cough originate and what are the differences in each type of cough?
From alveoli or small ariwaus - preceeded by deep inspiration.
paroxysms : start sorted and increase in volume as secretions move up the tracheobronchial tree
often have post-tussive retch
From mainstem bronchi- goose honk
Laryngeal cough - stimulus is often abrupt => reflex laryngospasm so this prevents deep inspiration priot to start of the cough and => rapid fire cough that is weak or ineffective + gagging.
From airway narrowing - only noted during exercies.
Other areas - nose, nasophyrinx, paranasal sinus, ear canals, diaphrgm and pericardium.
Describe different breathing patterns?
- Normal => 1:1 or 1:2 insp to expiratory
- Obstructive:
- Extrathoracic => increased insp effort and noise => prolonged insp phase (stertor/stridor)
- intrathoracic => increased exp effort and noise => prolonged exp phase (dynamic lower airway obstruction eg asthma, TB collapse)
- fixed airway obstruction - prolonged cycle + insp and exp noise eg gade IV tracheal collapse - Restrictive:
- ixed insp and expiratory difficulty
- reduced lung compliance or airflow vols (IPF, pneumonia, pleural space disease)
=> need increased airway pressure to expand lungs thus reduce tidal volume and increase RR
=> shallow rapid respiration.
(quiet/absent lung sounds = pleural space disease)
(increased adventitious lung sounds = parenchymal disease) - Compensation for both restrictive and obstructive + pleural space disease
=> Paradoxical breathing
- fatigue of the diaphragm => abdo muscles sucked in with inspiration and then move out with expiration.
PCR testing for URTi should be obtained using what type of swab?
polyester-tipped as residue in cotton tipped or calcium alginate may inhibit PCR assays
What fungal URTi diseases can be detected by PCR?
Blasto coccidio crypto histo asper Pneumocystis
What viral URTi diseases can be detected by PCR?
Canine distemper CAV2 Canine herpes Canine parainfluenze virus 2 Canine resp coronavirus HCN2 H3N8 H1NI Canine pneumovirus
FHV1
Feline calicivirus
What bacterial URTi diseases can be detected by PCR?
Bordertella chalmydia felis mycoplasma cynos mycoplasma felis Strep equi subsp zooepidemicus
What protozoal URTi diseases can be detected by PCR?
Toxo
Neospora
Acanthamoeba
What are the different classifications of pulmonary radiographic abnormalities? (5)
- Interstitial
- unstructured/diffuse
- structured/nodular - Alveolar
- Bronchial
- Pleural effusion
- Pneumothorax
What is a radiographic interstitial pattern and possible causes?
- Diffuse/unstructured
- generalized increase in parenchymal background opacity and decreased distinction of pulmonary vasculature
Causes: pneumonia (viral, haematogenous), pulmonary oedema, neoplasia (lymphoma), pneumonitis (Eg uraemic), hypoventilation, obesity - Nodule/s:
Discrete or coalescing soft tissue nodules
>2cm = mass
- Multiple solid nodules - mets, fungal, septic emboli
- Single solid mass - primary tumour, abscess
- Multiple cavitary nodules - mets, parasitic, mullae
- Solitary cavitary mass - primary tumour, abscess, bulla
What is a radiographic alveolar pattern and possible causes?
when air within the alveoli is replaced with soft tissue or fluid =>
- increase in overall opacity.
- air bronchograms
- lobar sign
- soft tissue silhouetting
causes:
Fluid - pul oedema, hemorrhage, inflam (bronchopenumonia)
Tissue - inflam (eosinophilic bronchopneumopathy), neoplasia, PTE
Other - atelectasis
What is a radiographic bronchial pattern and possible causes?
- thickened bronchial walls or infiltation of peribronchial space with fluid or cells
=> - thickened bronchi (tram tracks or donuts)
- bronchiectasis
- cranial or middle lung lobe atelectasis
- hyperlucent lung fields (due to air trapping)
Causes:
- allergic airways disease
- parasitic
- chronic bronchitis
What can nuclear scintigraphy be used to diagnose in relation to the respiratory system?
- lung function including regional pulmonary perfusion or lung ventilation to calculate regional ventrilation to perfusion ratios to localize areas of low V/Q within diffuse lung disease (Eg pre-biopsy/lung lobectomy)
- PTE (better than angiography)
- mucocillary clearance
How much fluid should be instilled for:
- BAL
- ETW
- TTW
- BAL 1-2ml/kg in large dogs. 2-4ml/kg in smaller dogs/cats
- ETW 0.5-5ml/kg
- TTW 0.5=5ml/kg
What are the limitations and complications of:
- BAL
- ETW
- TTW
- transthoracic needle aspirate or biopsy
- BAL
- req GA
- interstitial lung disease
- hypoxemia due to ventilation perfusion mismatch
- bronchospasm - ETW
- req GA
- only large airways/productive cough
- worsening respiratory disease/cough
- bronchospasm - TTW
- only large airways/productive cough
- only large dogs >15kg
- myst tolerate restraint
- not with bleeding issues or ventral cervical pyoderma
- worsening respiratory disease/cough
- bronchospasm
- SC empyseme
- haemorrahge
- cardiac arrhythmia
- hemoptysis
- tracheal laceration => pneumomediasteinum or pneumothorax
- infection along the needle tract
- airway obstruction from haemorrhage or haematoma - transthoracic needle aspirate or biopsy
- req imaging
- not in animals with bleeding issues, cystic or bullous lesion, penumothorax, pulmonary hypertesion. resp distress ro instability
- complications inc bleeding, pnumothroax, seeding along needle tract, death
What is the mechanism of action, spectrum of activity and contraindications for doxycycline?
Tetracycline
Time dependent bacteriostatic
Inhibits protein synthesis by irreversibly binding to 30S ribosome
May alter cytoplasmic membranes
Mycoplasma, spirochetes (borrelia), chalmydia and rickettsia.
Gram +ve bacteria. Staph and strep may be resistant
Some gram -ve bacteris inc bordertella, brucella, bartonella, Haemophilus, pasturela, shigella and yersinia. (not ecoli, klebsiella, bacteroides, enterobacter, proteus or pseudomonas)
Contraindications:
- hypersensitivity
- pregnancy as they are embryo toxic and can cause retardation of foetal skeletal development, discolouration of teeth and enamel hypoplasia
- severe liver dysfunction
- oesophageal stricture
- long term use can be assocated with overgrowth of bacteria/fungi
- excreted in milk
What is the mechanism of action, spectrum of activity and contraindications for Gentamycin?
Bacteriocidal
Concentration dependant
Water soluble
minimal protein binding + don’t cross BBB
Irreversibly binds to the 30S subunit to inhib protein synthesis.
Req ratio of 10+ peak plasma concentration to MIC and alkaline environment to improve efficacy.
Primarily gram -ve aerobes and staph
- Pus, necrotic tissue or cellular debris
- Hypersensitivity
- renal disease
toxicity risk - old/young, fever, kypokalaemia, prolongted treatment, sepsis, hypotension and dehydration. - ototoxicity
- patients with neuromuscular disorders (can cause peripheral neuropathys, neuromuscular blockade) or botulism
- care with sighthounds (smaller vol of distribution)
What is the mechanism of action, spectrum of activity and contraindications for Azithromycin?
Macrolide
Bacteriostatic
Penetrates cell wall and binds 50S ribosomal subunit
Accumulates and persists in macro, neuts and pulmonary epithelial lining fluid.
Treats babesia and toxo via inhibition of apicoplast (DNA containing organelle) protein translation => protozoal progeny death
Broad spectrum
Gram +ve
Some gram -Ve inc salmonella, bordetella, pasurella and haemophilus.
Effective to treat mycoplasma and chalmydia but does not eradicate3 these in cats, so not recommended.
Toxo and babesia
+ atovaquone for babesia gibsoni/microti and theileriosis
+ toltrazuril for cryptosporidiosis
+/- minocycline for pythium
** poorer bio-avail and excreted unchanged in bile in cats. Good bio-avail in dogs.
** possibly for oral papillomatosis and reducing gingivial hyperplasia assoc with cyclosporine
- hypersensitviity
- hepatic dysfunction
- with other meds that prolong QT interval inc azoles, cisapride, dolasteron, monifloxacin, erythromycin, ondansetron, amidaone, procainamide, sotolol
What is the mechanism of action, spectrum of activity and contraindications for Enrofloxacin?
Fluroquinolone
Bacteriocidal
concentration dependant
inhibition of bacterial DNA-gyrase (type II toposiomerase) preventing DNA supercoiling and DNA synthesis.
Concentrates in Macrophages. Gets into bone, synovial fluid, skin, muscle, pleural fluid.
Aerobes
gram neg bacilli and cocci
brucella, chalmudia, staph, mycoplasma and some mycobacterium.
- hypersensitivity
- small to med dogs <2-8m and large-giant <12-18m to avoid cartilage damage.
- can cause CNS stimulation
- undiluted has high pH and can cause arrhythmia, hypotension and MC degranulation
- not in cats - occular toxicity
What is the mechanism of action, use and contraindications for butorphanol?
K and O- opioid receptor agonist
u- receptor antagonis.
Antitussive - elevated CNS resp center threshold to CO2 but doesn’t depress respiratory center sensitivity
- Can cause a decrease in HR secondary to increased parasym tone ad mild decrease in art BP.
- Hypersensitivity
- head trauma, increased intracranial pressure or other CNS dysfunction.
- MDR1 mutation => prolonged sedation.
- excessive mucus
- severe liver/renal disease
What is different in tracheitis between dogs and cats?
Cat’s don’t always have a significant cough and it is usually associated with infectious feline resp disease
What area of the tracheal ring is flattened in collapsing trachea
Dorsoventral with laxity of the dorsal tracheal membrane
What factors are associated with the development of tracheal collapse?
- primary cartilage abnormality due to reduced glycoaminoglycans and chondroitin=> intrinsic weakness of the tracheal rings
- other factors that initiate progression to symptomatic stage inc:
- obesity
- cardiomegaly
- inhaled irritant/allergens
- periodonal disease
- resp infection
- recent endotracheal intubation.
- incerased intrathoracic pressure such as with pul. fibrosis
With collapsing trachea, what changes to the intrathoracic trachea are seen with inspiration and expiration?
inspiration: the redundant dorsal membrane is aspirated/subjected to negative intrathoracic pressure and can enlarge the tracheal lumen - seen as widening on rads at peak inspiration.
expiration: collapse seen as narrowing of tracheal lumen
For dogs with collapsing trachea that fail to respond to medical management and management of concurrent diseases, what are the surgical options?
Cervical tracheal collapse = extralumination tracheal rings
intrathoracic collapse = intraluminal self expanding stenting.
What are other causes of obstructive tracheal disease?
- collapsing trachea
- stenosis secondary to injury/FB
- intracheal tumours - osteochontroma, MCT, SCC, adenocarcioma, osteosarc, EM plasmacytoma, leiomyoma, fibrosarc
- tracheal granumola post stent
parasitic - lungworms (osleurs, filaroides) or cuterebra (remove with scope)
That is required to confirm that the cause of a cough is bordetella?
pleomorphic cocci or coccobacilli adhered to the cillia or epithelial cells +/- PCR
*PCR +ve bordetella can be isolated from healthy dogs so question whether +ve always means bordetella is the cause of the signs or if could indicatedincidental ro carrier state
What is the treatment for bordetella?
Uncomplicated - none
Unwell - doxy
Non-responsive to doxy - aerosolized gentamicin for 3 weeks.
*vx don’t work in dogs with active infection.
What is required to meet the definition of chronic bronchitis in dogs?
- Chronic cough for >2 months
- Excessive mucus
- Exclusion of other chronic cardiopulmonary diseases
Chronic inflam of the airways not related to any specific primary cause
inflam in the bronchial mucosa => increased mucus production
=>wall thickening + bronchomalacia => airflow obstruction
=> cough
=> sustains inflammation.
What is the sequelae of chronic bronchitis in dogs?
bronchectasis (dilation and destruction of bronchi walls)
bronchomalacia (collapse)
COPD is uncommon in dogs
What are common bronchoscopy findings associated with chronic bronchitis in dogs?
irregular mucosal surfaces with loss of normal glistening appearance
- granular and roughed aspiect
- partial bronchial collapse
- bronchiectasis
- increased mucus
What are the BAL findings associated with chronic bronchitis?
- increased mucus +/- hyperplasia of epithelial cells
- increase globlet cells
- increased Neut and macrophages.
What are the 5 main groups of drugs used to manage coughing, examples and their general mechanism of reducing cough?
- Inhaled corticosteroids: act directly on the airway mucosa reducing local inflam. Fluticasone, beclomethasone, budesonide
- Expectorant: increase vol and reduce viscosity of airway secretions. guaifenesin
- Mucolytics: modify structure of mucus glycoprotein and reduce mucus thickness. Guaifenesin, acetylcystine, bromhexin, ambroxol
- Cough suppressants: centrally acting antitissives that inhib cough reflex via the medullary cough center. Butorphanol, codeine, hydrocodone, dextromethorphan
- Bronchodilator: relax contracted airway smooth muscle during bronchospasm. Only really useful in feline asthma. Sal/Albuterol, Theo/aminophylline and terbutalinw.
