Common Acute Pulmonary Oedema exam questions for medical finals, OSCEs and MRCP PACES
Define and classify acute pulmonary oedema
- Rapid accumulation of fluid in the alveoli and parenchyma of the lung
- Cardiogenic pulmonary oedema: caused by elevated pulmonary capillary pressure due to decompensated LVF
- Non-cardiogenic: caused by injury to the lung parenchyma or vasculature
List the cardiac precipitants of acute pulmonary oedema
- Acute coronary syndrome (ACS)
- Cardiac arrhythmia e.g. atrial fibrillation (AF)
- Valvular heart disease
- Cardiac tamponade
List the non-cardiac precipitants of acute pulmonary oedema
- Non-compliance with medication
- Negatively inotropic medication
- Fluid overload
- High output cardiac failure
- Acute respiratory distress syndrome (ARDS)
By what mechanism do the symptoms dyspnoea, orthopnoea and PND occur?
- As alveolar oedema increases, diffusion of oxygen into the pulmonary capillaries is impaired, which manifests as dyspnoea; venous return to the already congested heart and lungs increases when the patient lies flat, which manifests as orthopnoea and paroxysmal nocturnal dyspnoea (PND)
What other symptoms would you enquire about in the history?
- Cough productive of pink, frothy sputum
- Ankle swelling
What signs on examination would be suggestive of LVF?
- Respiratory distress
- Bibasal crepitations
- Cardiac wheeze
- Displaced apex beat
- Third heart sound
What signs on examination would be suggestive of RVF?
- RV heave
- Raised JVP
- Peripheral oedema
- Third heart sound
What signs would you look for on CXR?
Non-compliance with medication
- Alveolar oedema
- Bats wing hilar shadowing and Kerley B lines
- Diversion to the upper lobes (distension of upper pulmonary veins)
- Effusions: blunting of the costophrenic angles
What postural adjustment may help a patient with acute pulmonary oedema?
- Sit the patient upright
Give pharmacological therapies excluding oxygen that you would institute
- Furosemide 40 mg IV
- Morphine 2.5-10 mg IV
- GTN IV infusion 1 mg/ml starting at 2 ml/hour and titrating upwards maintaining SBP >90 mmHg
If patients exhibit an inadequate response to the above therapies, what procedure can be initiated?
- Commence CPAP starting with a PEEP of 5 cmH2O and titrating up to 10 cmH2O
By what mechanisms does CPAP improve oxygenation?
- Delivers high flow oxygen
- Improves functional residual capacity (FRC)
- Recruits alveoli
- Splints airways
- Reduces the work of breathing
- Drives pulmonary oedema back into the circulation