Clinical exam and investigation of respiratory disease Flashcards
What history is important in respiratory disease? 6
Herd/individual problem Age Animal use General management and environment Disease time course and features Response to tx
What to observe from a distance
General behaviour, demeanor RR, effort and pattern Inspiratory/expiratory noise Nostril flare Nostril airflow Noises
General clinical exam - respiratory disease - 8
BCS Posture Abdominal effort Abdominal mm hypertrophy (heaves lines) MM Eyes (discharge) Jugular veins (SOL --> increased jugular pulse height) Pectoral oedema
Specific clinical exam - respiratory disease
Paranasal sinuses - symmetry and percussion, facial and maxillary
Pharyngeal area - GPs, LNs and larynx
Thoracic auscultation and percussion
Define empyema
= collection of pus in the pleural space
What should the larynx be looked at for?
look for asymmetry of the cricoarytenoideus dorsalis mm (horses). You can assess the movement of this muscle by the slap test where you slap the withers (gently) and then there is a reflex which causes this muscle to move.
Define lung consolidation
a region of (normally compressible) lung tissue that has filled with liquid, a condition marked by induration (swelling or hardening of normally soft tissue) of a normally aerated lung. It is considered a radiologic sign.
Is thoracic ausculation normally louder in foals and thin anials?
yes
What are the borders for auscultation in ruminants?
6th ICS (point on elbow) 9th ICS 9midway) 11th ICS (level with tuber coxae) Diaphragmatic border (straight, unlike equines)
Outline small animal auscultation
not a reliable indicator of respiratory disease. usually significant if noise is increased. Beware of referred noise from the URT.
What do crackles indicate?
small airways and alveoli
What do wheezes indicate?
partial obstruction of longer airways.
Why is it important to palpate the apex beat in small animals?
there may be caudal displacement of the apex beat due to a SOL.
What should further diagnostic tests be based on?
Focus on diagnositic goals:
- rule in/out DDx
- will results change therapy/managment options
- specific advantages/disadvantages of each test.
What can you examine using endoscopy of the RT in horses?
nasal passages GPs Nasopharynx soft palate larynx trachea (to bifurcation) At rest, minimal restraint, and exercise
What can you examine using endoscopy of the RT in small animals?
Trachea, mainstem bronchi an dlarger divisions of the main bronchi
How do you perform RT endoscopy in small animals?
Take radiographs first (artefacts following washes)
In patient able to tolerate GA with trachea of sufficient diameter to accommodate an endoscope.
Sternal recumbency.
Strengths - endoscopy of RT?
can detect disease of major airways AND dynamic disease of URT.
Weaknesses - endoscopy of RT?
unable to visualise smaller airways or parenchymal lesions
What techniques can be performed via endoscope? 3
aspiration
biopsy (discrete lesions)
FB retrieval
What possible tests can be conducted if viral infection is suspected?
Paired serology
Virus isolation - buffy coat, nasopharyngeal swabs
Viral Ag detection - FAT (nasopharyngeal swabs)
PCR - specific virus ID
What RespT samples can you perform cytology and/or bacteriology on? 6
nasopharyngeal swab endoscopically guided tracheal aspirate transtracheal aspirate BALV pleural fluid lung biopsy
When is a nasopharyngeal swab suitable?
Only suitable for bacterial culture of specific organisms that aren’t normally commensal of the pharynx - Streptococcus equi equi
How do you do a GP lavage?
Endoscope within GP and aspirate discharge or lavage and aspirate (sterile saline) - commensal organisms are present. Most commonly used for detection of Strep equi equi via culture and/or PCR
Describe endoscopically-guided tracheal aspirate (equine)?
position endoscope in trachea, advance catheter, 30ml sterile buffered saline, withdraw saline
How do you do endoscopically-guided tracheal aspirate (small animals)?
GA - go via ETT - blind wash - use plastic tube via ETT
Advantages - endoscopically-guided tracheal aspirate - 3
easy
sample representative of whole lung
non-invasive
Disadvantages - endoscopically-guided tracheal aspirate - 4
sample contaminated by pharyngral flora
contaminated by equipment
wide range of normal cell populations
cells tend to be poorly preserved
Why do a transtracheal aspirate?
to avoid orophryngeal contamination (uncommon, only do when you need a 100% accurate culture results)
Method - transtracheal aspirate - equines
surgically prepare site in lower third of trachea - instill LA - insert guide catheter (10 gauge, 3 inch) or needle between tracheal rings - insert sample catheter (16-14 gauge, 30cm) - instill 25-30mls sterile saline - withdraw sample - remove sample catheter first, then guide catheter
Advantages - transtracheal aspirate
- no pharyngeal contamination if procedure performed succesfully
- no specialised equipment
- useful in foals where standard endoscopes too large
Disadvantages - transtracheal aspirate - 3
- horse may cough catheter into pharynx and contaminate sample
- invasive procedure
- complications - cellulitis, SC emphysema
Indications - small animal transtracheal aspirate - 2
- Collection of tracheal secretions where endoscopy not available (no facilities or anaesthesia is contra-indicated)
- Direct direct access to airway in conscious patient
Method - BALV - equine
insert guide catheter into trachea if being used - advance BAL tube into bronchus until it will not advance further, then inflate balloon, instill 120-200mls sterile saline - withdraw sample
Advantages - BALV
- sample comes from area of tract most likely to be affected
- narrow range of cell populations (aids interpretation)
- equipment cheap
- accessible equipment (used in all large animals)
Disadvantages - BALV
site sampled may not be appropriate in animals with localised pulmonary abscesses or pneumonias
What does thoracocentesis allow you to do?
characterise pleural effusion.
therapy
Method - thoracocentesis - horse
under ultrasonographic guidance - select 7th or 8th ICS - above lateral thoracic vein - prepare surgically - instill LA - make a stab incision - use blunt teat cannula or drain closed from atmosphere
Method - thoracocentesis - small animal
- Cr of Cd to heart
- Site determined by radiography or ultrasound
- If fluid evenly distributed then 8th or 9th ICS, either side
- Use LA (not cats)
- Closed system
What do you analyse a thoracocentesis sample for? 3
- Cytology
- Protein (transudate - modified transudate or exudate)
- Triglyceride: cholesterol ratio - identify chylothorax (small animals only)
- Culture
Indication - lung aspiration
when discrete intrapulmonary lesion exits which cannot be accessed in any other way. only severely ill patients.
What is chylothorax identified (small animals)?
chylothorax fluid triglyceride higher than plasma triglyceride
Indications - lung biopsy
not frequently performed
used to ID specific pathology (e.g. interstitial pneumonia and neoplasia)
Disadvantages - lung biopsy - 2
- very invasive
- complications - uncontrollable haemorrhage and pneumothorax
Why would you take a faecal sample to investigate respiratory disease in small animals?
Angiostrongylus vasorum larvae
What cnabe seen with pulmonary radiography?
Pulmonary structures - locate specific pathology
Pleural cavity - fluid/gas
Mediastinum - masses, fluid, gas
What is CT useful for? 5
= Pleural, mediastinal and parenchymal structures
= high image quality and detailed sectional anatomical structure
= cheaper, quicker, better detail of lung tissue (vs. MRI)
= doesn’t require gating for respiration (vs. MRI)
= radiation exposure unlikely to be an issue in our patients
Outline thoracic ultrasonography - 5
- sound doesn’t penetrate normal aerated lung
- sound will penetrate non-aerated (diseased) lung
- lesions that don’t extend to surface aren’t visible
- characterises pleural effusion ( v. useful)
- obtain samples (pleurocentesis, lung biopsy)
List examples of pulmonary function tests -6
- tract exercise tests
- treadmill exercise tests
- oesophageal manometry
- flow-volume loops
- oxygen uptake
- blood-gas analysis
ALL can quantify disease effects and monitor response to therapy but all rarely used - mainly studies.
