Severe pulmonary oedema

Causes
Cardiovascular (usually left ventricular failure)post-MI, or ischaemic heart disease. Also mitral stenosis, arrhythmias, and malignant hypertension.
ARDS (any cause, eg trauma, malaria, drugs), look for predisposing factors, eg trauma, post-op, sepsis. Is aspirin overdose or glue-sniffing/drug abuse likely? Ask friends/relatives.
Fluid overload.
Neurogenic, eg head injury.
Differential diagnosis
Asthma/COPD, pneumonia, and pulmonary oedema are often hard to distinguish, especially in the elderly, where that may co-exist. Do not hesitate to treat all 3 simultaneously (eg with salbutamol nebulizer, furosemide IV, diamorphine, amoxicillin).

Symptoms
Dyspnoea, orthopnoea (eg paroxysmal), pink frothy sputum. NB: drugs; other illnesses (recent MI/COPD or pneumonia).

Signs
Distressed, pale, sweaty, pulse is up, tachypnoea, pink frothy sputum, pulsus alternans, JVP is up, fine lung crackles, triple/gallop rhythm, wheeze (cardiac asthma). Usually sitting up and leaning forward. Quickly examine for possible causes.

Investigations
CXR (cardiomegaly, signs of pulmonary oedema: look for shadowing (usually bilateral), small effusions at costophrenic angles, fluid in the lung fissures, and Kerley B lines (linear opacities).
ECG signs of MI.
U&E; cardiac enzymes, ABG.
Consider echo.
Plasma BNP may be helpful if diagnosis in question.