Breathlessness, Dyspnoea

Dear patients

Thank you for your most interesting questions and thank you for trusting me to manage you health.

Breathlessness
Dyspnoea is the perception of breathlessness and may be exertional or, when more advanced, occur at rest. It may only occur when lying down (orthopnoea). Is the breathlessness a recent development? Is it episodic?
Ask how far the patient can walk without stopping (often an unreliable history) and how many pillows he/she uses in bed at night (in orthopnoea). Look for digital clubbing, central cyanosis and chest wall deformities.
Pulmonary causes

• Pneumonia, e.g. bacterial, viral.
• Bronchitis—acute or chronic.
• COPD.
• Acute asthma.
• Pneumothorax—even a small pneumothorax may acutely exacerbate dyspnoea in patients with pre-existing chronic pulmonary disease.
• Interstitial lung disease—e.g. sarcoidosis, fibrosing alveolitis, extrinsic allergic alveolitis, pneumoconiosis.
• Bronchogenic carcinoma.
• Foreign body obstructing bronchus (esp. children—peanut in right main bronchus).
• Pleural effusion—unilateral or bilateral.
• Ascites (diaphragmatic ‘splinting’).
• Lymphatic carcinomatosis (Note: CXR may appear normal in early stages).
• Pulmonary embolism ± infarction—single, multiple, recurrent.
• Pulmonary hypertension—1° or 2°.
• Pulmonary oedema—acute or chronic.
• Adult respiratory distress syndrome (ARDS).

Note: Remember metabolic acidosis—diabetic and alcoholic ketoacidosis, lactic acidosis (in metformin-treated patients, especially if renal impairment).

• Also
•  Salicylate poisoning.
•  Methanol (metabolised to formic acid).
•  Ethylene glycol (metabolised to oxalic acid).
• Other causes
•  Associated with angina pectoris/acute coronary syndromes.
•  Acute myocardial infarction (MI).
•  Valvular heart disease, VSD.
•  Anxiety.
•  Hyperventilation syndrome.
•  Obesity.
•  Kyphoscoliosis.
•  Metabolic acidosis—e.g. severe salicylate poisoning, DKA, lactic acidosis, hepatic or renal failure (acute or chronic).
•  Anaemia 
•  Diaphragmatic/respiratory muscle paralysis, e.g. Guillain-Barré syndrome.
•  Generalised neuromuscular disease, e.g. motor neurone disease (MND).
•  Acute laryngeal oedema, e.g. angio-oedema, diphtheria.
•  Laryngeal obstruction, e.g. laryngeal carcinoma.
•  External compression of larynx, e.g. retrosternal goitre.
•  Laryngeal spasm, e.g. 5 serum Ca2+.

Note: Occasionally, diabetic ketoacidosis may present in the absence of marked hyperglycaemia. However, true ‘euglycaemic’ ketoacidosis is rare (<1% of all cases. In alcoholic ketoacidosis, plasma glucose may not be elevated and Ketostix® reaction may be misleading.

Preliminary investigations should include

•  CXR.
•  ABGs (± blood lactate).
•  12-lead ECG.
•  FBC.
•  Venous plasma glucose.
•  Ca2+.
• Other tests may be indicated
•  CT chest.
•  V/Q scan. 
•  Spiral CT (if acute PE suspected).

• Bronchoscopy.
• Lung biopsy.
• Peak flow rate.
• Respiratory function tests.
•  Echocardiogram.
• Serum salicylate levels.
•  U&E.
•  LFTs.
•  ESR.