Acute Pulmonary Oedema Pharmacotherapy

Acute cardiogenic pulmonary oedema is rapid fluid overload of the lungs from raised left heart pressure, and treatment relieves congestion, lowers afterload and treats the cause. Non-invasive ventilation and nitrates act within minutes, and diuretics take longer.

Positioning and oxygen. Sit upright, give oxygen for saturation under 94 percent, and start continuous positive airway pressure of 5 to 10 cm H2O early if breathlessness continues.

Cause search. Acute coronary syndrome, arrhythmia, hypertensive crisis, valve disease, myocarditis, kidney failure and drug non-adherence.

First line. Nitrate (when systolic blood pressure allows), loop diuretic, and positive airway pressure.

Hypotension or shock. Use the cardiogenic shock approach: an inotrope such as dobutamine, with noradrenaline for pressure.

Avoid. Routine morphine, because of harm, and nitrates in systolic pressure under 90 to 100 mm Hg, severe aortic stenosis, right ventricular infarction, and recent phosphodiesterase 5 inhibitor use (24 to 48 hours).

Special groups.

• Children: furosemide 1 mg/kg intravenously.

• Pregnancy: furosemide 20 to 40 mg and nitrates are used, and peripartum cardiomyopathy and pre-eclampsia need specialist care.

• Kidney failure: higher doses of furosemide are needed, and dialysis or ultrafiltration if there is no response.

• East Africa: rheumatic mitral stenosis with atrial fibrillation is a recognised cause, so control the heart rate with care and avoid large vasodilator doses that drop preload.

• Glyceryl trinitrate: 400 to 800 micrograms sublingually, repeated every 5 minutes. Infusion 10 to 20 micrograms/min, increased by 5 to 10 micrograms/min every 3 to 5 minutes, to a maximum of 200 micrograms/min, keeping systolic pressure over 100 mm Hg.

• Furosemide: 40 mg intravenously (20 to 40 mg if never treated, 1 to 2.5 times the usual oral dose in chronic users), doubled after 1 to 2 hours if urine output is poor. Doses of 80 mg are used in kidney impairment.

• Dobutamine: 2.5 to 20 micrograms/kg/min for low output.

• Noradrenaline: 0.05 micrograms/kg/min, titrated to a mean arterial pressure of 65 mm Hg.

Monitoring. Respiratory rate, oxygen saturation, blood pressure, ECG, urine output (catheter if needed), potassium, magnesium and creatinine. Check urine volume 1 to 2 hours after the diuretic.

Stop rules. Stop nitrates for systolic pressure under 90 mm Hg. Stop diuretics at euvolaemia, or for hypotension, hypokalaemia or acute kidney injury.

Referral and escalation. Seek cardiology review for acute coronary syndrome, arrhythmia, new valve or mechanical lesion, or shock. Seek intensive care for failing non-invasive ventilation or exhaustion.

Common errors. Giving morphine, using nitrates in hypotension, under-dosing furosemide in kidney disease, and omitting the cause search.