Acute Pulmonary Oedema

Question 1

Aetiology of acute pulmonary oedema

Answer 1

-Accumulation of fluid within alveoli of the lung
-Impairs gas exchange and leads to hypoxia and respiratory failure
-Main causes split into Cardiogenic and non-cardiogenic
-Cardiogenic.
=Myocardial infarction from coronary disease
=Valvular heart disease
=Arrhythmia
-Non-cardiogenic – infectious (ARDS), neurogenic

Question 2

Pathophysiology of acute pulmonary oedema

Answer 2

-Decreased arterial blood pressure causes sympathetic activation and release of neurohormones (i.e. norepinephrine).
-Decreased renal perfusion activates the renin-angiotensin-aldosterone system (RAAS) which retains Na and water
-Increased circulating neurohormones cause peripheral vasoconstriction (increased afterload) and cardiotoxicity leading to secondary myocardial injury
-Splanchnic vasoconstriction leads to redistribution of blood contributing to increased preload and eventually, pulmonary volume overload

Question 3

Symptoms of APO

Answer 3

-Breathlessness
-Orthopnoea and PND
-Chest pain (hypoxic)
-Haemoptysis (oink frothy sputum)
-Anxiety

Question 4

Clinical signs of APO

Answer 4

-Tachypnoea
-Cyanosis (hypoxic)
-Tachycardia
-Hypotensive (hypertensive)
-Sweaty and pale
-Elevated JVP (distention)
-Gallop rhythm
-Crepitations, rales
-Peripheral oedema
-Hepatomegaly

Question 5

Investigations

Answer 5

-Oxygen saturations
-Arterial blood gas
-ECG (MI, tachycardia)
-Chest X Ray (oedema- widespread airspace opacification, dilated heart, upper lobe venous diversions/ bat loop)
-Bloods including FBC, -U+E, LFT, Troponin (myocardial damage), lactate (tissue perfusion), BNP
-Echocardiogram (valvular/ regional wall abnormality)

Question 6

Treatment

Answer 6

-Sit patient upright
-Oxygen therapy (aim Sp02 > 94%)
-IV diuretic – Furosemide 50mg
-IV Nitrate (GTN) if BP allows
=Nitrates at low dose cause vasodilatation reducing preload. At higher doses they use vasodilatation thereby reducing afterload
-Consider IV Morphine- dilatation but suppresses respiratory drive
-CPAP/BiPAP

Question 7

Prognosis and long-term care

Answer 7

-Treat underlying cause (MI- primary PCI, arrhythmia etc)
-Avoid precipitants (excess salt, fluids, hypertension)
-Medication adherence (ACEi, beta blocker, MRA, diuretics)
-Consider other HF treatments such as CRT pacemaker/LVAD/heart transplant if appropriate