Causes of dyspnoea
Respiratory
1. Airways disease
COPD
Asthma
Bronchiectasis
Cystic fibrosis
Laryngeal or pharyngeal tumour
Bilateral cord palsy
Tracheal obstruction or stenosis
Tracheomalacia
Cricoarytenoid rheumatoid arthritis
2. Parenchymal disease
Interstitial lung diseases
Diffuse infections
Acute respiratory distress syndrome (ARDS)
Infiltrative & metastatic tumour
Pneumothorax
Pneumoconiosis
3. Pulmonary
circulation
Pulmonary embolism
Chronic thromboembolic pulmonary hypertension
Pulmonary arteriovenous malformation
Pulmonary arteritis
4. Chest wall & pleura
Effusion or massive ascites
Pleural tumour
Fractured ribs
Ankylosing spondylitis
Kyphoscoliosis
Neuromuscular diseases
Bilateral diaphragmatic paralysis
Cardiac
Left ventricular failure
Mitral valve disease
Cardiomyopathy
Pericardial effusion or constrictive pericarditis
Intra-cardiac shunt
Anaemia
Non-cardiorespiratory
Psychogenic
Acidosis
Hypothalamic lesions
Onset of dyspnoea
Seconds to minutes favours:
Hours or days favours:
Weeks or longer favours:
Asthma
Pulmonary embolism
Pneumothorax
Pulmonary oedema
Anaphylaxis
Foreign body airway obstruction
Exacerbation of COPD
Cardiac failure
Asthma
Respiratory infection
Pleural effusion
Metabolic acidosis
Pulmonary fibrosis
COPD
Interstitial lung disease
Pleural effusion
Anaemia
Differential diagnosis of dyspnoea of sudden onset
Presence of pleuritic chest
pain favours:
Absence of chest pain
favours:
Presence of
central chest
pain favours:
Presence of
cough & wheeze
favours:
Pneumothorax
Pleurisy
Pneumonia
Pulmonary embolism
Trauma
Pulmonary oedema
Metabolic acidosis
Pulmonary embolism
Myocardial
infarction &
cardiac failure
Large pulmonary
embolism
Asthma
Bronchial irritant
inhalant
COPD
What is dyspnoea?


Subjective sensation of breathing discomfort
o This experience varies widely
Breathlessness arises when there is a recognition by the subject of an inappropriate relationship
between respiratory work & total body work
o There is an imbalance in the drive to breath & the mechanical effort
Clinical causes of dyspnoea





Respiratory
Cardiac
Chest wall restriction/muscle weakness
o Eg/ MND, cachexia, spinal cord lesions, muscular dystrophies
Metabolic/anaemia
o Eg/ Obesity, metabolic acidosis
Psychogenic
Mechanisms of dyspnoea
Increased sense of respiratory effort due to:
1. Increased drive (demand) for ventilation - exercise, metabolic acidosis, hypoxia, anxiety
2. Increased load (work of breathing) - resistive load, elastic load
3. Decreased strength of respiratory muscles
Diagnosing dyspnoea



History
Examination findings
Suitable/targeted investigations:
o CXR, ECG, ABG's, basic bloods
o Lung function, CT, VQ, exercise test, echo
Physical findings as clues


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
Wheeze = airways
o Not just asthma, could be COPD, heart failure, obesity
Crepitations/crackles = terminal lung units
o Eg/ pulmonary oedema, pneumonia
Stony dullness = pleural
o Eg/ pleural effusion
Silent zone (no findings) = pulmonary vessels
o Eg/ pulmonary embolism