Hypervolemia, also known as fluid overload, is the state wherein there is an excessive buildup of fluids in the body. The body fluids are primarily composed of sodium and water . This increase in the level of body fluid, results to excessive circulating volume, which cannot be pumped effectively by the heart causing heart failure .
- 60% of the body is made up of water. This is distributed in the different body compartments.
Picture 1: An illustration of the water composition in our body
- Electrolytes are charged particles. These are responsible for the balance of total fluid in the body . The electrolyte, sodium, has an electrical charge that enables it to attract the water.
- According to the National Institutes of Health, the recommended intake for each individual depends on several factors such as altitude, climate, diet, and activity.
- The recommended intake by Institute of Medicine for men is 3 liters (13 cups) of beverages. On the other hand, women are advised to drink 2.2 liters (9 cups) of beverages everyday.
- The water loss in the body involves factors such as urination, perspiration, defecation, and other insensible loss. The normal water loss or output of the body is 1,600 mL.
- In hypervolemia, there is an increase in the level of body water and body sodium content [3, 4, 5, 6, 7].
Electrolytes, especially sodium, play a significant role in maintaining the balance of fluid in the body. The concentration of the electrolytes in the body dictate where the fluid goes.
For example, if there is a higher concentration of an electrolyte within the cells, that is where the fluid will move. On the other hand, if there is a higher electrolyte concentration outside the cells, the fluid will move outside the cells. So, with this, the body needs to maintain the normal concentration of electrolytes to obtain fluid balance. 
Sodium plays an integral part in the regulation of the total amount of water in the body. Also, it is important in the generation of the electrical signals in the body. When there is an excessive amount of sodium in the body, it is excreted through urination to maintain the balance.
If the Sodium level in the body becomes too high or too low, it can cause several malfunctioning of the cells which may lead to fatal conditions. The normal sodium level in the blood is 135-145 milliEquivalents per liter (mEq/L). 
In Hypervolemia, the sodium levels become too high. This results to feeling of intense thirst by an individual leading to more water intake. As a consequence, the pituitary gland releases antidiuretic hormone (ADH) which causes the kidneys to retain more water in the body. Therefore, increasing the amount of water in the bloodstream. 
Excessive sodium or fluid intake
1. Intravenous (IV) therapy:
- This occurs when the intravenous fluid is administered in a rapid rate or larger volume than what is advised by the doctor.
- When administration of the wrong intravenous fluid is done, this may cause imbalance in the Sodium levels in the blood.
- For perioperative patients who are undergoing intravenous therapy, it is advised that hypotonic fluids are avoided in the initial stages of the therapy. Also, frequent measurement of the electrolytes, especially sodium, is recommended. [10, 11]
2. Transfusion reaction by blood transfusions:
- Transfusion reaction caused by rapid infusion or larger volume of blood products may cause fluid overload .
3. Excessive dietary sodium intake 
Sodium or water retention
1. Heart Problems
- Congestive Heart Failure: In this condition, the heart is unable to effectively pump the blood throughout the body. This results to backing up of blood in the veins, leading to increased fluid volume.
- Chronic or acute heart disease [7, 13]
2. Kidney Disorders
- Nephrotic syndrome: In nephrotic syndrome, deficiency in albumin (protein) occurs. The decrease of albumin in the blood, results to transferring of the fluids from the blood to the tissues which causes edema or swelling. When the kidney detects this, it will retain more salt and fluid in the body.
- Glomerulonephritis: This results to failure of the kidneys to excrete excess fluids in the body. [13, 14]
3. Liver Cirrhosis
- It contributes to the fluid overload since this can also cause increased levels of blood plasma .
4. Hyperaldosteronism 
- Corticosteroid therapy
- Chemotherapy drugs [7, 13]
6. Reaction to Stress
- Patients, who are injured or underwent a surgery, have more difficulty in eliminating the excess fluid in their body.
- Hormonal disturbances: For head injury and post-operative patients, antidiuretic hormone (ADH) increases. This increase in the ADH levels cause retention of water and sodium. 
- Low protein intake 
Fluid shift into the intravascular space:
- For burn patients, shifting of fluid into the intravascular space occur when fluid remobilization is done.
- The infusion of plasma proteins such as albumin
- Intravenous therapy using hypertonic saline solutions or hypertonic fluids like Mannitol. 
- Cushing’s syndrome 
- Also known as swelling, is caused by the fluid buildup in the legs and arms. 
- This is the state where the excess fluid in the body accumulates in the abdomen. 
3. Cardiovascular problems:
- Pulse: Characterized as strong and rapid
- Hypertension (elevated blood pressure)
- Elevated central venous pressure (CVP)
- Increased Pulmonary Artery Pressure (PAP)
- Jugular vein distention
- Presence of extra heart sound: S3 heart sounds
- Low hemoglobin or hematocrit levels [7, 15]
4. Respiratory problems
- Respiratory pattern changes
- Presence of crackles or rales upon auscultation
- Dyspnea (difficulty of breathing)
- Orthopnea (difficulty of breathing when lying down)
- Paroxysmal nocturnal dyspnea
- X-ray results show pulmonary edema 
5. Urinary problems
- Specific gravity changes
- Intake is more than output
- Azotemia: characterized by elevated BUN and other creatinine-containing components 
6. Neurological changes
- Mental status changes such as confusion or lethargy
- Anxiety and restlessness 
Picture 2: Illustration of the symptoms manifested by patients with Hypervolemia
- Congestive heart failure (most common)
- Pulmonary Edema [13, 16]
Note: If symptoms of acute pulmonary edema are seen, immediately start treatment without waiting for the investigations. 
1. Medical Interview:
- The doctor will ask the patient about his medical history as well as the signs and symptoms related to the disease. 
2. Laboratory Tests:
- Complete blood count: This is done to determine the presence of anemia and infection.
- Serum urea, creatinine and electrolytes : These are assessed to examine the renal function and to rule out electrolyte imbalance contribution.
- Urinalysis, Glomerular Filtration Rate (GFR)
- Liver function tests : To assess protein and albumin levels [2, 15]
3. Imaging studies
- ECG: This will help in determining for any presence cardiac arrhythmias, hypertrophy or infarction.
- Chest X-Ray: This may identify pulmonary edema and pneumonia.
- Echocardiography: To rule out the cause of cardiac dysfunction, whether ventricular failure, large pulmonary embolus or cardiac tamponade. 
Other possible investigations
- B-type natriuretic peptide (BNP): This can aid in diagnosing heart failure.
- Arterial blood gases : This is ordered by the doctor if the cause of dyspnea is unclear.
- Fluid balance charts and serial weights : For monitoring treatment improvement.
- Further investigations may be done depending on the suspected cause of the disease. 
Hypervolemia Differential Diagnosis
Other causes of dyspnea
- Pulmonary embolism (without added lung sounds)
- Acute anaphylaxis may lead to wheezing, swollen tongue or lips.
- Bronchospasm which usually occurs in patients with asthma or chronic obstructive pulmonary disease.
- Basal lung crackles may result from poor effort in inspiratorion . This may be relieved after doing deep breathing.
- Fine inspiratory crackles may manifest in patients with Fibrosing alveolitis. 
Other causes of elevated jugular venous pressure (JVP)
- Cardiac tamponade or constrictive pericarditis may result to elevated JVP.
- Pulmonary embolism
- Superior vena cava occlusion (veins of upper limb and neck gets distended and non-pulsatile) 
Other causes of peripheral edema
- Pre-eclampsia: For women who are 20 + weeks pregnant, make sure to check their urine for protein.
- Lymphedema which is specifically a non-pitting edema.
- Hypoproteinaemia: This may occur due to malnutrition, nephrotic syndrome, disease of the liver or malabsorption.
- Other causes of Venous obstruction (unilateral) are severe varicose veins, Deep venous thrombosis (DVT), Pelvic mass (which may also involve pregnancy), and obstruction of inferior vena cava. 
Other causes of ascites
- Portal Hypertension
- Liver Cirrhosis
- Malignancy 
Hypervolemia treatment depends on the condition of the patient. It also includes treating the underlying cause of the fluid overload that occurred. 
- Diuretics: These medications aid the patients to excrete the excess fluids in their bodies.
- Inotropes: These are helpful for patient who have heart failure. [13, 17]
2. Diet modification
- Low salt in diet is recommended for patients with hypervolemia. This is to reduce the work of kidneys and let them function better. 
3. Isolated ultrafiltration
- It uses an extracorporeal filter to eliminate isotonic fluid. This treatment facilitates removal of excess sodium in the body and it avoids occurrence of electrolyte imbalance throughout the treatment duration. 
Picture 3: Picture of a machine used for isolated ultrafiltration
Hypervolemia – Expected Outcomes
- Facilitate the elimination of excess sodium and water
- Treat the underlying cause and relief of symptoms
- Maintain electrolyte and water balance in the body
- Improve the patient’s prognosis or quality of life 
1. Make sure to provide optimum treatment for renal and heart failure.
2. Be cautious while giving intravenous fluid administration, including blood transfusion.
3. For post-surgical patients, proper and advised postoperative fluid replacement therapy should be done.
4. In case of severe sepsis septic shock or sepsis, the guidelines on Surviving Sepsis Campaign should be included for information about the ideal fluid therapy.
5. Perform assessment of postoperative oliguria cases at bedside.
- In spite of no complications, there are chances that oliguria may occur post-operatively, as a normal response of the body to surgery.
- For post-operative patients who are experiencing oliguria, hypovolemia is suspected due to the administration of sodium-rich intravenous fluid.
- Serious attention needs to be given to intravascular hypovolemia, and it can clinically be assessed by signs like capillary refill, elevation in pulse and blood pressure, central venous pressure.
- Hence, it is essential to interpret the output of urine on the basis of the above mentioned intravascular hypovolemic signs, and also the normal physiological response of surgery on urine output. 
12. http://www.rcsed.ac.uk/fellows/lvanrensburg/classification/commonfiles/blood_transfusion.htm#Fluid overload
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