Hypervolemia

Hypervolemia Facts

Hypervolemia, also known as fluid overload, is an excessive increase in the volume of fluid volume. It is an abnormal increase in blood plasma volume, which causes an elevated blood volume. ^{[4, 2]}

The condition involves expansion of the volume of extracellular fluid and covers the interstitial and intravascular space. The cause can be the overproduction of the isotonic fluid that is composed of sodium and water. ^{[1,2, 3,6]}

Hypervolemia and hyponatremia

Hyponatremia is a condition caused by abnormally low levels of sodium in the body. As an electrolyte, it regulates the amount of water in and around the cells. Hyponatremia causes the rise of water levels causing the cells to swell and retain water. ^{[2, 4, 6, 7, 8]}

Signs and Symptoms

One or more of these signs and symptoms may manifest when there is excess plasma volume:

• Increased rate of respiration and shortness of breath. This is caused by the decreased number of red blood cells. Once blood is diluted, the body compensates it by an increase in respiration to enable all the cells to get enough oxygen.
• An increase in the pulse rate, which is caused by the overload on the circulatory system and elevated contractility of the cardiac muscles.
• Central venous pressure (CVP), pulmonary artery pressure (PAP) and shift of fluids from plasma cause edema in the ankles and the legs.
• An increase in the volume of fluids among the lung pleural spaces causes labored and difficulty in breathing, a condition called pulmonary edema. The collection of the fluid in the lungs also causes paroxysmal nocturnal orthopnea (difficulty of breathing when lying down) and dyspnea (difficulty in breathing).
• Crackling when auscultated due to the increase in hydrostatic pressure in the pulmonary arteries
• Moist skin as the body tries to eliminate the excess fluid through sweating
• Jugular vein distention caused by increased volume of the blood and the preload.
• Excessive and rapid weight gain because of the building up of the extracellular fluids. There is also fluid buildups in the abdomen as the fluid drains from different parts of the body.
• The feeling of a third heart sound, also known as S3 gallop during auscultation due to rapid filling of the articular part of the heart during systole and overloading of the ventricular part during diastole.
• There is also an abnormality in the renal function that leads to specific alterations of gravity, change in the levels of the electrolytes, oliguria and azotemia.
• Neurological changes such as change of the mental status characterized by lethargy or confusion, anxiety and restlessness. ^{[2,3, 5,8,9,10, 11]}

Hypervolemia and hypertension

Circulatory overload and an increase in the mean arterial pressure causes hypertension along with pulmonary artery pressure (PAP) and central venous pressure (CVP).  ^{[1, 2, 3, 4, 5, 7, 11]}

Hypervolemia and pregnancy

Pregnancy-induced hypertension called pre-eclampsia is common in women during their gestation period. It characterized by edema and presence of proteins in the urine. The expectant mother should get treatment for fluid retention promptly. ^{[1, 3, 5, 10]}

Hypervolemia pathophysiology

• In the normal function, the body creates processes in which it enhances the electrolyte equilibrium, relinquishes, and compensates fluid. The process is achieved through the help of such hormones as aldosterone, antidiuretic hormone ADH and atrial natriuretic peptide ANP. The hormones influence the release of sodium and water that are essential to the body from the nephrons of the kidneys.
• Here is an illustration of the fluid balancing mechanism. If an electrolyte is in higher concentration within the cells than the outside, fluids will move from outside the cells to inside the cell. If the electrolyte concentration outside the cells is higher than on the inside of the cell, the fluid moves outside. This body mechanism maintains the normal concentration of the electrolyte and balance of the fluid. ^{[1, 3, 10, 11]}
• There may be cases of hypervolemia when they are cases of elevation of volume levels in the intramuscular space. The cause of the condition could be due to the shifting of the fluids from interstitium to the plasma, the excessive occurrence of intravenous fluids reduced water and sodium excretion and chronic stimuli on the renal part of the kidney causing the conservation of both the elements. [1, 3]
• The elevation of the fluids in volume overloads the circulatory systems and leads to abnormally amplified contractility of the cardiac muscles, increases the mean artery pressure MAP and elevates the capillary hydrostatic pressure. The latter action leads to a shifting of the fluids to the interstitial space, which results in edema.  ^{[1,2,3,4,5,10,11]}
• If the case of hypervolemia gets severe or in case the patient suffers from a history or cardiac dysfunction, the body’s compensatory mechanisms may not work. Moreover, he or she may experience a shortfall of urinary excretion of water and sodium. In a worse case, the aldosterone and antidiuretic hormone may not be stopped from causing an elevation of mean arterial pressure. The result is usually pulmonary edema, which is followed by heart failure. ^{[1, 3,]}

 Causes of Hypervolemia

• Excessive intake of fluid or sodium
• Intravenous (IV)therapy
• Hypervolemia may occur if an intravenous fluid is administered in a larger volume or rapid rate than directed by the doctor.
• When a wrong intravenous fluid is administered, it may alter the sodium levels in the blood.
• Use of hypotonic fluids on perioperative patients who are undergoing an intravenous therapy [1,3]
• Body’s reaction to transfusion when a large volume of blood products are infused or the process if infusion done rapidly [3]
• Excessively taking of dietary sodium  ^{[1,2,3,4, 5, 11]}

Retention of water and sodium

Heart problems

• Acute and chronic heart diseases
• Congestive heart failure; where the heart is unable to pump the blood effectively throughout the body. The blood backs up in veins causing an increase in fluid volume. [1,3,5]

Kidney disorders

• Glomerulonephritis that makes the kidneys unable to excrete excess fluids from the body.
• Nephritic syndrome that causes the deficiency in as protein called albumin. The deficiency leads to transfer of fluids from the blood to the body tissues, which ends in edema. The kidney on the other hand, tends to retain more fluid and salt. [7,8]
• Liver cirrhosis also contributes to the overload of the fluid as it leads to increase in plasma levels ^{[1,2, 3]}
• Certain medications such as chemotherapy drugs and corticosteroid therapy drugs ^[1,2,3]
•  Low protein intake [3]
• The body’s reaction to stress such as after an injury of surgery. Head injury patients all experience increased antidiuretic hormone levels that lead to sodium and water retention. ^[3,8]

Shift of fluids into intravascular space

• In burn patients during fluid remobilization
• Intravenous infusion of plasma proteins ^{[ 1,3]}

Leg edema because of a result of capillary leak syndrome
Source: Wikimedia

Diagnostic tests and lab values

Below some of the common laboratory tests used for accessing a person’s hydration status

• Hematocrit test – This test measures the percentage of the blood that is made up of red blood cell. The test is often a part of complete blood count. Hematocrit decreases at the increase of hydration
• Normal adult male values; 40.7 % to 50.3 %
• Normal female values : 36.1 % to 44.3 %
• Sodium test – The test measures the amount of sodium in the blood and is often done when the doctor suspects electrolyte imbalance. Overhydration causes hyponatremia, which are low amounts of sodium in the blood.  Normal values in adults is 135-145 mEq/L
• BUN (Blood Urea Nitrogen Tests) – The test measures the amount of nitrogen and urea in the blood as part of kidney function evaluation. BUN decreases with overhydration. Normal adult values: 10-20mg/dl
• Serum Osmolality Test – The test seeks to determine the number of solute in the blood or serum sample. It is a common test in the evaluation of hyponatremia (loss of sodium). Osmolality decreases with overhydration. [6, 8]

Pitting edema before and after the application of pressure on the skin. The action shows the extent of swelling in the leg.
Source: Wikimedia

Treatment of Hypervolemia

There are several treatments and nursing interventions that can manage the problem as listed below

• Medication – Patients are given diuretics to help in the excretion of the excess fluids while heart failure patients are given inotropes
• Modification of diet – The doctor may recommend a low salt diet for hypervolemia patients to ease the workload on the kidneys.
• Isolated ultrafiltration – The process uses an extracorporeal filter for the elimination of isotonic fluid. It is effective in the removal of excess sodium from the body. [1, 2,3,4,5, 9, 10, 11]

References

1. http://www.healthresource4u.com/hypervolemia.html
2. http://www.ihealthblogger.com/2013/07/Hypervolemia-Definition-Symptoms-Diagnosis-and-Treatment.html
3. http://howshealth.com/hypervolemia/
4. Mayoclinic.org
5. http://patient.info/doctor/fluid-overload
6. Physio-pedia.com. Fluid Excess/Intoxication – Physiopedia, universal access to physiotherapy knowledge. [Internet]. 2015 [cited 22 December 2015].
7. Weir M. Hypervolemia and Blood Pressure: Powerful Indicators of Increased Mortality Among Hemodialysis Patients.
8. Androne AS e. Relation of unrecognized hypervolemia in chronic heart failure to clinical status, hemodynamics, and patient outcomes.  – PubMed – NCBI [Internet]. Ncbi.nlm.nih.gov. 2015 [cited 22 December 2015].
9. Merck Manuals Professional Edition. Hyponatremia – Endocrine and Metabolic Disorders [Internet]. 2015 [cited 22 December 2015].
10. Hypervolemia.com
11. Drjohnivanoffmdtulsa.com. Fluids Hypervolemia And The Heart