Armando Hasudungan
Biology and Medicine videos

Acute Dyspnea

Dyspnea is a subjective experience of breathing discomfort; patients experience qualitatively distinct sensations that vary in intensity. Acute dyspnea might be secondary to an acute problem, or it might be an exacerbation of an existing disease (eg, asthma, chronic obstructive pulmonary disease, heart failure).

Overview Dyspnea (Greek dys, meaning “painful,” “difficult,” and pneuma, meaning “breath. Dyspnea is the medical term for subjective experience of breathlessness or shortness of breath. Dyspnea can be acute when it develops over hours to days and chronic when it has been for more than four to eight weeks.

Acute Chronic
Pulmonary edema COPD
Asthma Left cardiac failure
Injury to chest wall and intrathoracic structures Asthma
Spontaneous pneumothorax Pulmonary vascular disease
Pulmonary embolism Psychogenic dyspnea
Pneumonia Anemia (severe)
Acute respiratory distress syndrome Hypersensitivity disorders
Pleural effusion Pleural effusion
Pulmonary Haemorrhage
Foreign body aspiration

The usual causes of acute dyspnea in children differ from those in adults. In children, upper airway infection (e.g., epiglottis, laryngitis, or acute laryngotracheobronchitis) is a common cause.

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Dyspnea may be due to diseases in virtually any organ system, whether caused by interference with breathing, increased demand for breathing, or weakening of the respiratory pump. In most cases, however, patients with dyspnea can be categorized into one of two groups: respiratory related dyspnea or cardiovascular related dyspnea.

Respiratory Disease Cardiovascular Disease
Pulmonary Embolism Acute left ventricular failure
(heart failure)
Pulmonary Infection (Pneumonia, bronchitis) Acute Coronary Syndrome
Upper airway obstruction (Aspiration, anaphylaxis)
COPD/Asthma exacerbation


Acute onset Dyspnea Associated signs/symptoms
Foreign object Sign of choking, Inspiratory and expiratory stridor
Anaphylaxis Angioedema, stridor, rash, pruritus
Pulmonary Haemorrhage
Pulmonary Embolism Acute dyspnea, fever, haemopytsis, pleuritic chest pain, signs of DVT
Pneumothorax Acute dyspnea, one sided-pleuritic chest pain
Cardiac Tamponade Cardinal Quatrad: hypotension,↑JVP, tachycardia, pulsus paradoxus
Acute Coronary Syndrome Retrosternal chest pain, radiates to jaw/neck, diaphoresis and feeling of impending doom
Gradual onset Dyspnea  Associated signs/symptoms
Asthma exacerbation Pallor/Cyanosis, ↑resp rate, accessory muscle use, wheezing, silent chest, muscle exhaustion
COPD exacerbation
Anaemia From Haemorrhage: Shock
Epiglottitis  “Barking cough”
Diabetic ketoacidosis History of polyuria, polydipsia, polyphagia, and progressive weakness; signs of severe disease include hyperventilation, altered mental status, and abdominal pain


  • History
    • Drugs history
      • Amiodarone
      • Methotrexate
Pharmacology Amiodarone is a K+ channel blocker (class III antiarrythmic). It acts on the myocardium to delay repolarization and increase duration of the action potential. It also decreases SA and AV conduction rate. Side effects (6Ps): Prolongs action potential duration, Photosensitivity, Pulmonary fibrosis and inflammation, Pigmentation of skin, Peripheral neuropathy, Peripheral conversion of T4 to T3 is inhibited (Hypothyroidism). 
  • Examination
    • Smoker signs
    • BMI
NYHA classification of dyspnea (For Heart Failure)
I nil at rest, some on vigorous activity
II nil at rest, dyspnea on moderate exertion
III mild dyspnea at rest, worse on mild exertion
IV significant dyspnea at rest and worse on slight exertion


MRC Dyspnea score
1 Not troubled by breathlessness except on strenuous exercise
2 Dyspnea when hurrying or walking up a slight hill
3 Walks slower than contemporaries on level ground due to dyspnea, or has to stop for breath when talking at own pace
4 Stops for breath after walking 100m or less on ground level
5 Too breathless to leave house, or when getting dressed


  • Pulse oximetry
  • Full Blood Count
  • EUC
  • Electrolytes
  • Cardiac troponin
  • Brain natriuretic peptide (BNP) or N-terminal pro-BNP
  • D-dimer
  • Chest X-ray
  • Electrocardiogram (ECG)

Specific Dyspnea

  • Orthopnea – dyspnea when lying flat. patient usually sleeps with multiple pillows
  • Paroxysmal nocturnal dyspnea – episodes of breathlessness at night. It is associated with pulmonary oedema
  • Cheyne–Stokes breathing is characterized by alternating periods of hypoventilation and hyperventilation
  • Kussmaul breathing – Diabetic ketoacidosis who manifests with “air hunger”: rapid breathing
  • Hyperventilation – dysfunctional breathing, breathing off CO2 causes ↓CO2 and so increases pH

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