Dyspnoea/SOB Flashcards
Understand the mechanism behind dyspnoea, differential diagnosis of dyspnoea and investigations to aid diagnosis
What are five main categories of causes of dyspnoea?
- Respiratory
- Cardiovascular
- Neuromuscular/restrictive
- Systemic illness
- Psychogenic e.g. panic attack/anxiety
List common causes of respiratory diseases that cause SOB. List 4 acute causes and 4 chronic causes
Acute/subacute
1. Chest infection/pneumonia
2. Pulmonary embolism (acute, constant)
3. Asthma/COPD exacerbation
4. Pneumothorax
Chronic
1. COPD (progressive)
2. Interstitial lung disease
3. Auto-immune conditions with lung involvement e.g. sarcoidosis, rheumatoid
4. Lung cancer
List 4 cardiac causes of breathlessness
- Heart failure - pulmonary oedema
- Heart attack/ACS
- Atrial fibrillation, arrythmias e.g. tachycardias
- Valvular heart diseases - reduced output
List some anatomical causes of SOB
- Neuromuscular disease e.g. phrenic nerve paralysis, NMJ condition, Guillain-Barre
- Kyphosis/scoliosis
- Chest wall deformity
- Compression-related e.g. rib fractures, obesity, ascites
List some systemic conditions that cause SOB
- Anaemia: reduces oxygen-carrying capacity
- Sepsis
- Anaphylaxis
- Metabolic acidosis/ DKA (respiratory compensation)
- Acute renal failure
- Liver cirrhosis
List 5 of the most acute causes of SOB
Vascular: PE, MI
Immune-related: anaphylaxis, asthma,
Trauma: pneumothorax, foreign object inhalation, cardiac tamponade
What are the key signs and symptoms associated with breathlessness?
- Chest tightness and wheezing
- Chest pain – pleuritic or non-pleuritic
- Cough
- Tachypnoea/ increased respiratory effort
- Tachycardia
- Fever, fatigue
- Cyanosis
What are the primary physiological mechanisms that cause SOB?
Increased respiratory drive due to hypoxia, hypercapnia, or acidosis.
It can also be caused by mechanical factors like airway obstruction or reduced lung compliance.
What are some special characteristics of breathlessness in heart failure that should be asked? Which one is particularly pathognomonic for CHF?
- Paroxysmal nocturnal dyspnoea (PND): patient wakes up gasping for air —pathognomonic
- Worse with positioning: orthopnoea, ++pillows when sleeping
- Severity - quantify (New York classification)
- Associated with fatigue, peripheral oedema
- Might have a ‘cardiac cough’ due to pulmonary oedema – white or pink, frothy sputum due to small amount of blood.
What is the New York classification of dyspnoea severity in heart failure patients?
1- no symptoms,
2-with exertion,
3- with normal activity,
4- at rest
What is the MRC dyspnoea scale? How When is it used?
To quantify functional disability/severity of breathlessness.
0 = Zero difficulty (No apparent dyspnoea)
1 = Dyspnoea walking ↑
2 = Dyspnoea when walking in a pair (slower than people of the same age)
3 = Cannot walk 100 metres (three digits)
4 = Number four, you’re on the floor - too breatheless to leave the house
What are the top 5 conditions in hospital that cause dyspnoea?
- Heart failure
- COPD exacerbation
- Pneumonia/chest infection
- Pulmonary embolism
- ACS
- Asthma
- Anaemia
What are two causes of instantaneous SOB?
- PE
- PNeumonthorax
What immediate investigations should be performed for a patient with acute SOB?
- Vital signs - RR, O2 sats, cap refill
- Respiratory exam
- Bedside ECG
- ABG
- Chest X-ray
- D-dimer
- FBC/CRP
What are four main domains to assess when taking a history of presenting complaint for a patient presenting with SOB?
- Acuity – onset and triggers, duration
- Character: Severity/functional disability
- Exacerbating factors: timing, positional/orthopnoea, inspiration/expiration
- Associated features: e.g. chest pain, cough, haemoptysis, syncope, wheeze/stridor, oedema
