Intravenous furosemide for fluid overload in acute decompensated heart failure
In acute decompensated heart failure (a sudden worsening), excess fluid is treated first with an intravenous loop diuretic such as furosemide, which makes the kidneys pass salt and water.
Remember
In acute decompensated heart failure with fluid overload (a build-up of fluid in the lungs and tissues), get the fluid out first with an intravenous loop diuretic such as furosemide; long-term heart drugs are added once the patient is stable.
In acute decompensated heart failure (a sudden worsening), the failing heart cannot keep up with the blood returning to it. Pressure builds up behind the heart, so fluid backs up into the lungs, causing breathlessness, and into the tissues, causing swelling (oedema). This build-up of fluid is called congestion, or fluid overload.
The first aim is to remove the excess salt and water. The first drug is an intravenous loop diuretic such as furosemide, given into a vein in hospital. By blocking salt reabsorption in the loop of Henlé (a section of the kidney), it makes the kidneys pass salt and water in the urine.
As the circulating volume falls, so does the filling pressure of the heart (preload). That relieves oedema and breathlessness and can improve cardiac output. Giving the drug into a vein means its effect does not depend on absorption from the gut.
Other measures support this. Oxygen is given if the patient is hypoxaemic (has a low blood oxygen level), and intravenous nitrates, which widen blood vessels, may be added.
Long-term drugs such as beta-blockers (drugs that slow the heart and reduce its workload) protect the heart over time rather than clearing fluid quickly. Beta-blockers are started or restarted once the patient is stabilised.
Key facts
- First drug
- an intravenous loop diuretic such as furosemide, given into a vein in hospital, is the first drug for fluid overload in acute heart failure.
- Action
- it blocks salt reabsorption in the loop of Henlé, so salt and water are passed in the urine.
- Effect
- a lower circulating volume lowers preload and relieves oedema and breathlessness.
- Why intravenous
- given into a vein, the effect does not depend on absorption from the gut.
- Alongside
- oxygen if the patient is hypoxaemic, and sometimes intravenous nitrates.
- Later
- beta-blockers are started or restarted once the patient is stabilised.
Exam traps
- Beta-blockers (drugs that slow the heart and reduce its workload) are started or restarted once the patient is stabilised, but they do not make the kidneys excrete sodium and water, so they are not the initial treatment for congestion.
- An inotrope (a drug that strengthens the heartbeat) such as dobutamine is used for low output heart failure and does not remove fluid, so it does not relieve fluid overload.
- Spironolactone is a relatively weak diuretic that is part of the long-term treatment of chronic heart failure, so it does not relieve congestion quickly; a loop diuretic is used first to control volume overload.
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