Fluid overload means that there is too much fluid in the body. The increased level of fluid results in an excessive volume of fluid flowing around the circulatory system. This can overwork the heart and lead to heart failure.
What are the symptoms?
If the total amount of fluid in the body is raised above normal, this increases the fluid circulating through the arteries and veins. Fluid can settle in the lungs (pulmonary oedema) causing breathlessness. The heart has to work harder to deal with all this fluid and this can result in heart failure. The symptoms of heart failure are breathlessness, tiredness, and swelling of the legs and feet.
Read more about the symptoms of fluid overload.
What are the causes?
The heart and kidneys act together to control the fluid content and sodium content in the body. If something goes wrong with this system (for example, heart failure or kidney damage), fluid overload can occur.
Another common cause is treatment with fluids administered through a vein. The fluids may be a mixture of chemicals and sterile water, nutrient solutions or blood. If too much fluid is administered, or the mixture of chemicals is imbalanced (too much sodium, for example) fluid overload can occur.
Learn more about the causes of fluid overload.
How is it diagnosed?
The features of fluid overload are very similar to those of other conditions, and these conditions need to be ruled out. They include lung and heart problems, circulatory disorders, liver disease and thyroid disease.
You will need heart tests, X-rays, blood tests and measurements of your fluid input and output (fluid balance).
What treatment is available?
Treatment of the underlying cause is important. The effects of fluid overload on the lung and heart also need treating. Separate leaflets are available on these topics.
What is the outlook?
This depends on the cause. If you were fit and well before the problem occurred (for example, if you had too much fluid after a routine operation), you stand a good chance of recovery. If your fluid overload was due to heart or kidney problems, the outlook (prognosis) depends on how easily the underlying condition responds to treatment.
What are the symptoms of fluid overload?
The excess fluid circulating around the body can cause waterlogging of the lungs, leading to breathlessness. The medical term for this is acute pulmonary oedema. 'Acute' means 'of quick onset'.
If fluid overload goes on for a long term it eventually leads to heart failure. This causes tiredness, breathlessness and swelling of the legs and feet. The type of swelling that occurs is called pitting oedema. This means that when the swelling is pressed with a finger, it leaves an indentation, or 'pit'.
What are the causes of fluid overload?
The heart and kidneys interact to control fluid volume and the sodium content in the body. This system is quite complex. More information about it can be found in the separate article written for doctors, called Fluid Overload.
- Treatment with fluid can be a cause. It is sometimes difficult to calculate how much fluid the body needs. This can happen when nutritional fluid or blood is given through a drip. The risk of overload may be increased if you are elderly, you have had a major injury or operation, or your kidneys or heart do not work as well as they should,
- Sometimes the problem is not so much fluid as too much sodium. Sodium is a chemical that occurs naturally in the body and needs to be at a certain level in the blood and other body fluids. If too much sodium is given, the body will retain water to try to correct this.
- People with heart failure may have fluid overload,
- People whose kidneys suddenly stop working properly (acute kidney injury) can be similarly affected.
- When something goes wrong with this system it's known as cardiorenal syndrome.
How is fluid overload diagnosed?
A number of conditions produce signs and symptoms that resemble fluid overload, and these need to be excluded. These conditions include:
- Lung problems, such as blood clots, infections, asthma.
- Heart problems, such as inflammation of the covering of the heart (pericarditis).
- Problems with the venous circulation or lymphatic circulation.
- Disorders causing a low protein level in the blood (hypoproteinaemia).
- Liver disease.
- Thyroid disease.
Will I need any tests?
It's not surprising that with all these conditions to rule out you will need several tests. These may include:
- Heart tests: heart tracing (electrocardiogram, or ECG) and ultrasound scanning of the heart (echocardiogram, or echo).
- Chest X-ray.
- Blood tests to check your kidney function, blood count, liver function, blood gases.
- A special test for heart failure, called B-type natriuretic peptide (BNP).
- Charts to check how much you drink and pee and any weight changes in response to treatment.
What are the treatment options for fluid overload?
The treatment depends on your symptoms.
See separate leaflet on the treatment of sudden-onset (acute) fluid overload of the lungs, called Pulmonary Oedema. There is also more information available on heart failure treatment. See separate leaflet called Heart Failure.
What is the outlook for fluid overload?
This depends on the underlying cause and how well you were before the fluid overload occurred. For example, if the fluid overload was due to a problem with your heart, the outlook (prognosis) depends on how treatable your heart condition is. If the fluid overload resulted from being given too much fluid during intravenous treatment, the outlook will depend on the reason why you needed intravenous fluid in the first place. If you were given it because you had just had a simple operation but were well beforehand, the outlook should be good once the overload is corrected. However, if intravenous treatment was given because you had a serious problem such as extensive burns, correcting the overload may be more complicated.
Further reading & references
- Kim IY, Kim JH, Lee DW, et al; Fluid overload and survival in critically ill patients with acute kidney injury receiving continuous renal replacement therapy. PLoS One. 2017 Feb 14;12(2):e0172137. doi: 10.1371/journal.pone.0172137. eCollection 2017.
- Byrne L, Van Haren F; Fluid resuscitation in human sepsis: Time to rewrite history? Ann Intensive Care. 2017 Dec;7(1):4. doi: 10.1186/s13613-016-0231-8. Epub 2017 Jan 3.
- Glatz T, Kulemann B, Marjanovic G, et al; Postoperative fluid overload is a risk factor for adverse surgical outcome in patients undergoing esophagectomy for esophageal cancer: a retrospective study in 335 patients. BMC Surg. 2017 Jan 13;17(1):6. doi: 10.1186/s12893-016-0203-9.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but makes no warranty as to its accuracy. Consult a doctor or other healthcare professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Laurence Knott
Dr Adrian Bonsall