Presenting Signs: Cough and Dyspnoea

Question 1

1. Define cough.
2. Define Dyspnoea.

Answer 1

1. Sudden expiratory effort against a closed glottis, results in noisy expulsion of air from lungs.
2. Difficulty breathing w/ increased effort.

Question 2

1. Tachypnoea.
2. Hyperpnoea.
3. Orthopnoea.
4. Cyanosis.

Answer 2

1. Increased RR.
2. Increased respiratory effort (deeper breaths) w/o dyspnoea.
3. Difficulty breathing in while laying down. Cats often sit or stand to facilitate breathing w/ elbows abducted and neck extended.
4. Blue MM colouration due to reduced oxygenation.

Question 3

1. Aim of cough.
2. Cough receptors.
3. Cough arc reflex.
4. How does heart disease result in cough?

Answer 3

1. Aim is protective reflex to clear excess secretions / foreign materials.
2. Cough receptors in large airways and low density cough receptors in nose, sinuses, pharynx, pleura.
   - mechanical receptors for mucus, FB etc.
   - chemical receptors for acid, heat etc.
3. Cough arc reflex:
   - afferent pathway: sensory nerves (vagus).
   - cough centre: medulla oblongata.
   - efferent pathway: via vagus, phrenic and spinal motor nerves to diaphragm, abdominal wall and muscles.
4. Enlarged LA.
   Tachypnoea caused by pulmonary oedema.

Question 4

Harmful effects of coughing.

Answer 4

Exacerbate airway inflammation and irritation.
Emphysema.
Pneumothorax.
Weakness and exhaustion.
Dissemination of infections.

Question 5

Causes of dyspnoea and tachypnoea.

Answer 5

Respiratory:
- obstructive – fixed or dynamic obstruction.
- restrictive – decreased volume of air that the lungs can hold.
Cardiac.
Haematologic.
Metabolic.
Neurological.

Question 6

Approach to the patient presenting w/ dyspnoea and cough.

Answer 6

Assess patient:
- O2.
- Reduce stress – consider sedation and environment.
Hx.
PE.
Problem list and differentials.
Dx investigations.
Interventions/management.

Question 7

Considering the causes of the cough.

Answer 7

Cardiac or respiratory?
- what causes coughing in heart disease?
- any other signs of heart disease?
- any other signs of cardiac failure (i.e. dyspnoea and/or tachypnoea)?
– murmur?
- sinus arrhythmia?
– Y –> CHF v unlikely.
– N –> does not help.
- cats w/ heart disease rarely cough.

Question 8

1. Likely cause of dyspnoea and cough in young patients?
2. Likely cause of dyspnoea and cough in older patients?
3. Breed dispositions for diseases causes coughing and dyspnoea.

Answer 8

1. Lungworm?
2. Neoplasia? Chronic bronchitis?
3. Brachycephalic or dolichocephalic.
   Working/outdoor lifestyle - airway FB?
   CKCS and others = MMVD.
   Brachycephalic breeds - BOAS.
   Toy breed dogs e.g. Yorkie - tracheal collapse.
   Siamese cat - Feline asthma/chronic bronchitis.
   Westie - idiopathic pulmonary fibrosis.

Question 9

Taking a general history.

Answer 9

Vac status, contact w/ other animals.
Worming history (lungworm).
History of trauma.
Exercise tolerance.
Environmental influences: rural/urban/tobacco smoke.
Additional clinical signs: - vomiting or regurgitation?

Question 10

Characterising the clinical signs.

Answer 10

Coughing vs panting.
Reverse sneezing, gagging, retching.
Onset and duration:
- acute versus chronic >2mths.
- progressive?
The cough:
- initiating factors.
- Productive vs non-productive.
- sound: moist, gurgling, dry, goose honk.
- Presence of terminal retch.
Change in sound of bark/purr/meow.

Question 11

1. Is a patient suffering from BOAS suffering from an obstructive dyspnoea or restrictive dyspnoea?
2. Is a patient suffering from BOAS suffering from expiratory dyspnoea, inspiratory dyspnoea or both?
3. Is a patient w/ pneumonia likely the present with an obstructive dyspnoea or restrictive dyspnoea?
4. Is a patient w/ pneumonia likely to suffer inspiratory dyspnoea, expiratory dyspnoea or both?

Answer 11

1. Obstructive.
2. Inspiratory.
3. Restrictive.
4. Both.

Question 12

Distant exam of the patient.

Answer 12

Assess patient first and stabilise if necessary (O2).
Observe patient’s posture.
Observe patient’s respiratory rate a rhythm.
- inspiratory vs expiratory effort.
- shallow vs laboured.
Listen for:
- URT noise.
– stertor (like snoring) vs stridor.
- wheezing (LRT).

Question 13

Closer PE.

Answer 13

Once stable.
Palpate:
- cranial mediastinum compressibility in cats (gently!)
- thoracic cavity trauma/deformities.
- tracheal pinch.
Assess LNs.

Question 14

Thoracic auscultation.

Answer 14

Auscultate:
- crackles.
- wheezes.
- HR and rhythm: respiratory sinus arrhythmia?
- heart murmur.
- muffled/lack of heart sounds.
Percuss:
- increased/decreases resonance.

Question 15

Respiratory causes of dyspnoea and tachypnoea?

Answer 15

URT:
- obstructive disorders (e.g. laryngeal paralysis / tracheal collapse / BOAS).
LRT:
- obstructive disorders: luminal (e.g. mucus) vs mural (mass or bronchospasm e.g. feline asthma, chronic bronchitis).
Pulmonary parenchyma:
- restrictive disorder / reduced lung capacity e.g. pneumonia, haemorrhage, oedema.
Pleural space:
- restrictive disorder/reduced lung volume: e.g. pleural effusion.
- obstructive disorder e.g. mediastinal mass.

Question 16

Non-respiratory causes of dyspnoea and tachypnoea.

Answer 16

Haematological disorders:
- decreased O2 carrying capacity (anaemia or methaemoglobinaemia).
Metabolic disorders:
- compensatory mechanism to acidosis (DKA).
- muscular weakness (hypokalaemia).
Neurological disorders:
- brain, spinal cord, peripheral nerves.

Question 17

Diagnostic investigations of coughing and dyspnoeic patient.

Answer 17

Assess O2:
- SpO2.
- Arterial blood gas analysis.
Blood and faecal tests.
Diagnostic imaging:
- assess pleural space disease.
Laryngeal exam.
Advanced techniques e.g. bronchoscopy.

Question 18

Clinical pathology investigations.

Answer 18

Haematology:
- Neutropenia?
- Eosinophilia?
- Thrombocytopenia?
Biochemistry.
Lungworm?
- Angiostrongylus Antigen ELISA (blood test: AngioDetect).
- Faecal smear or Baermann for lungworm.
- Can get false negatives.
- Consider empirical treatment trial w/ fenbendazole or moxidectin.
NT-pro BNP.
- Cardiac vs respiratory cause.
- in pleural effusion (cats).
– negatives reliable.

Question 19

Investigations of cough/dyspnoea under GA.

Answer 19

ONCE STABILISED!
Laryngeal exam.
- structure: mass, collapse.
- function: paralysis.
Diagnostic imaging.

Question 20

1. Which lung pattern is best described as doughnuts and tram lines?
2. Which lung pattern is best described as cloudy/fluffy/patchy?
3. Which lung pattern is best described as looking through net curtains?
4. Which lung pattern is best described by cannon balls.

Answer 20

1. Bronchial.
2. Alveolar.
3. Interstitial diffuse.
4. Interstitial nodular.

Question 21

Diagnostic imaging in the coughing and dyspnoeic patient.

Answer 21

Ultrasound:
- thoracic mass?
- E.g. T-FAST techniques (look for thoracic fluid).
Radiography:
- pulmonary patterns (bronchial, alveolar, interstitial).
- heart and vessels.
- masses.
- pleural space.
CT:
- likely referral.

Question 22

Sampling for further investigation.

Answer 22

BAL:
- blind or guided by bronchoscope.
- pre-treat cats with Terbutaline.
- cytology.
- bacterial culture.
- Bordetella bronchiseptica and Mycoplasma spp. PCR.
Tracheal wash?
Lung FNA:
- ultrasound-guided.
- peripherally located lesions.

Question 23

Further investigations - bronchoscopy.
Method.

Answer 23

Pre-treat cats w/ terbutaline.
Pass through trachea in small patients.
Through ET tube in larger patients.
Look at tracheal mucosal surface.
Tracheal structure.
Facilitate collection of BAL samples.
Removal of FBs.
- can be difficult to retrieve seed head due to spike directions.
- lung lobectomy.

Question 24

Oxygen supplementation options for patients with dyspnoea.

Answer 24

Flow-by.
Mask.
Nasal prongs.
Nasal catheter.
Oxygen hood.
Oxygen cage/incubator.
Intubation w/o mechanical ventilation.

Question 25

1. Advantages of flow-by O2 supplementation. 2. Disadvantages of flow-by O2 supplementation. 3. Advantages of mask. 4. Disadvantages of mask.

Answer 25

1. Useful during initial assessment. Easy and well tolerated. 2. Needs someone to hold the tube. Fraction of O2 inhaled by patient is quite low - 25-40%. 3. Easy. Useful for recumbent patient. 4. Patient may not tolerate. Fraction of O2 inhaled by patient not very high - 50-60%.

Question 26

1. Advantage of nasal prongs. 2. Disadvantages of nasal prongs? 3. Advantages of nasal catheters. 4. Disadvantages of nasal catheters. 5. Fraction of O2 inhaled by the patient w/ nasal catheters?

Answer 26

1. Easy to place. 2. Often dislodge - designed for humans. 3. Can be used longer term. Well tolerated. Easy access to patient. Easy to place. 4. More invasive / time consuming. 5. Unilateral = 40%. Bilateral = 80%.

Question 27

1. Disadvantages of O2 hood. 2. Advantages of O2 cage / incubator. 3. Disadvantages of O2 cage/incubator.

Answer 27

1. Risk of hyperthermia. CO2 build-up. Humidity. Low fraction of O2 inhaled by patient at 30-40%. 2. well-tolerated. well suited for small patients. 3. Limited access for patient handling (but may have access via side). Need to monitor humidity and temperature. Fraction inhaled O2 60% and drops when open door.

Question 28

1. Indication for intubation w/o mechanical ventilation? 2. FiO2 w/ intubation w/o mechanical ventilation? 3. Additional O2 supplementation techniques.

Answer 28

1. Upper airway obstruction. 2. 100%. 3. Positive and expiratory pressure. Mechanical ventilation. Referral.