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Course: Fundamentals of Nursing�Topic: Fluid and Electrolyte Balance

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Module Goals

Learners will be able to:

Describe the pathophysiological processes involved in fluid regulation and electrolyte balance.
Identify risk factors for fluid and electrolyte imbalance.
Interpret laboratory studies used to assess fluid and electrolyte balance.
Apply the nursing process to care of clients with fluid and electrolyte imbalance.

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Fluid and Electrolyte Physiological Process

Ernstmeyer & Christman, 2021

Fluids and electrolytes move in and out of cells.

Any alterations can disrupt one or more body systems.

Body fluid

Made up of various components: solutes, water, electrolytes, plasma, proteins.
Found intracellularly and extracellularly.

Intracellular fluids

Found inside cells.
Protein, water, solutes, electrolytes.

Extracellular fluids

Found outside cells.
Most abundantly: sodium.

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Extracellular Fluid

Two main types of extracellular fluid.

Intravascular fluid

Fluid found in vascular system (arteries, veins, capillaries).
Whole blood volume.

Red and white blood cells, plasma, platelets.

Considered most important component of maintaining overall fluid balance within the body.
Loss of intravascular fluid leads to hypovolemia.

Ernstmeyer & Christman, 2021

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Extracellular Fluid

Interstitial fluid

Fluid found between cells outside of the blood vessels.
Also known as edema.

Extracellular fluid not classified as intravascular and interstitial fluid is known as transcellular fluid.

Examples: fluid found in cerebrospinal system, gastrointestinal system, intrapleural and synovial places.

Ernstmeyer & Christman, 2021

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Fluid Movement

Dependent on:

Vascular tissue being intact.

Prevents fluid leaking out of blood vessels.

Normal amounts of protein content.

Protein in blood (albumin) allows water to be held inside vascular compartment known as oncotic pressure.

Normal hydrostatic pressure within blood vessels.

When fluid is contained and exerting pressure on what it is contained in.

Ernstmeyer & Christman, 2021

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Fluid Movement

Filtration: Occurs when fluid and solutes are pushed through a permeable membrane by hydrostatic pressure in order to be excreted.

Osmosis: Occurs when there is water movement from a lesser concentrated area to a more concentrated area in order to neutralize and equalize solute concentrations.

Ernstmeyer & Christman, 2021

Contact info: info@nursesinternational.org

Example of fluid exerting hydrostatic pressure: Blood inside capillaries

Filtration is important and plays a large role in balancing the body’s fluids and acid-base balances. A major organ that depends on filtration is the kidney. Within the kidney, the glomerular capillaries filtrate fluid and waste and allow it to be excreted from the body, aiding in balancing fluid and acid-bases.

Osmosis occurs through a semipermeable membrane, allowing only some solutes to pass through. This blocks large molecules keeping them out. Osmosis does not require energy to move, but rather moves by a concentration gradient, making it a form of passive transport. A real world example of osmosis is when you consume a large amount of salty food. Within the blood, the sodium levels raise, allowing osmosis to occur by pulling fluid into the intravascular compartment from the both the intracellular and interstitial compartments to allow the solute concentration to equalize. When this happens, the cells shrink in size. These cells shrinking in size cause common signs of dehydration, a headache and/or dry mucous membranes.

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Solute Movement

Controlled by one of three methods: Diffusion, active transport, or filtration.
Diffusion

Occurs when solutes move from an area of higher concentration to an area of lower concentration to attempt to balance.
Moves from an area of higher concentration to lower so there is no energy expenditure.

Active transport

Occurs when solutes and ions move across a cell membrane from lower concentration to higher.
Requires energy because it is going against the concentration gradient.

Ernstmeyer & Christman, 2021

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Solute movement, continued

Filtration, which is due to the hydrostatic pressure of blood , causes a net outward movement of fluid at the arteriolar end of a capillary.

The hydrostatic pressure of the blood forces fluid at the arteriolar ends of capillaries into the interstitial spaces of the tissues.

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Regulation of Fluid and Electrolytes

Ernstmeyer & Christman, 2021

Regulation must occur to prevent excess accumulation or deficits of fluids and electrolytes.
Assists in maintaining blood pressure
Water balance mechanisms:

Thirst
Renin-Angiotensin-Aldosterone System (RAAS)
Antidiuretic hormones (ADH)

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Thirst

Regulates fluid intake:

When fluid is lost, it increases sodium within the intravascular space. This increases serum osmolality.
Serum osmolality: the concentration of dissolved solutes found in the blood.
Osmoreceptors in the hypothalamus signal the kidneys to release ADH to retain fluid after detecting a rise of serum osmolality levels.
The osmoreceptors trigger the sensation of thirst to encourage oral intake.

Ernstmeyer & Christman, 2021

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Renin-Angiotensin-Aldosterone System (RAAS)

Assists in regulation of fluid output and blood pressure:

Kidney cells, specialized in making renin, secrete renin into the bloodstream when there is decreased blood pressure.
The liver releases angiotensinogen and renin acts on it, converting it to angiotensin I, then converting it to angiotensin II.
Angiotensin II increases blood flow to vital organs through vasoconstriction.
It also stimulates the adrenal cortex to allow for aldosterone to be released.

Ernstmeyer & Christman, 2021

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Fluid Output

Output mainly occurs through releasing of urine

Consists of approximately 60% of daily fluid loss.
Normal production is approximately 1,500 mL of urine per day and 300 mL/hr.

Decreased production can signal early dehydration or kidney dysfunction.

Additional fluid outputs:

Sweat, stool, lungs.
Known as “insensible losses” and cannot be measured.
Consists of about 40% of daily fluid loss.

Ernstmeyer & Christman, 2021

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Fluid Imbalances

Two types of fluid imbalances:

Excessive fluid volume (hypervolemia)
Deficient fluid volume (hypovolemia)

Referred to imbalances in the extracellular compartment

Although, can cause fluid to move into the intracellular space dependent on the amount of sodium in the blood

Ernstmeyer & Christman, 2021

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Hypervolemia

Ernstmeyer & Christman, 2021

Intravascular compartment contains an increased fluid amount.
At risk clients:

Cirrhosis
Pregnancy
Kidney failure
Heart failure

Symptoms:

Dyspnea
Crackles in lungs
Ascites
Pitting edema

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Hypervolemia

Ernstmeyer & Christman, 2021

Treatment:

Dependent on cause of hypervolemia
Diuretics prescribed
Sodium and fluid restriction

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Hypovolemia

Ernstmeyer & Christman, 2021

Occurs when fluid loss is greater than fluid input
At risk clients:

clients taking diuretics
Chronic diseases -- diabetes mellitus & kidney disease
Infants and children
Older adults
People who exercise and work in outdoor heat

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Hypovolemia

Ernstmeyer & Christman, 2021

Symptoms:

Dry mouth, dry skin
Headache, elevated heart rate,
Dark urine, decrease urinary output, dizziness
Change of mental status, feeling very thirsty
Children specific: lack of wet diapers for three or more hours, unusually drowsy, sunken eyes, sunken fontanelles, crying without tears, irritability

Treatment:

Increased oral intake
Intravenous fluids if necessary

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What would the nurse do?

A parent takes their infant into a clinic stating that they are concerned because their baby is “not drinking enough bottles.” As the nurse is completing their physical assessment, what signs and symptoms does the nurse look for to assess for dehydration?

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Intravenous Solutions

Ernstmeyer & Christman, 2021

Prescribed to clients experiencing deficient fluid volume
A method to restore fluid to the intravascular compartment
Assists in facilitating movement of fluid between compartments
Three types of IV fluids:

Isotonic
Hypotonic
Hypertonic

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Isotonic Solution

Fluids that have a similar concentration to those particles located in the blood.
Example: 0.9% Normal Saline (0.9% NaCl).
The IV fluid that is similar to the blood concentration, the infused fluid stays in the intravascular space and therefore osmosis does not occur between compartments.
Used when:

Clients have hypovolemia to raise their blood pressure.

Cautions:

Excess isotonic solution can cause hypervolemia.

Ernstmeyer & Christman, 2021

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Hypotonic Solutions

Solution that has a lower concentration compared to the dissolved solutes found in the blood.
Example: 0.45% Normal Saline (0.45% NaCl).
During infusion, results in osmotic movement of water to move into intracellular space from intravascular compartment.
Used for:

Cellular dehydration.

Cautions:

Excess of fluid moving into cells from intravascular compartment.
Can cause cerebral edema, worsening hypovolemia, hypotension.

Ernstmeyer & Christman, 2021

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Hypertonic Solutions

Greater concentration of dissolved particles in solution compared to blood.
Example: 3% Normal Saline (3% NaCl).
Results in osmotic movement of water out of the cells and moving into the intravascular space.

Dilutes amount of solute in the blood.

Uses:

Cerebral edema
Hyponatremia

Caution:

Monitor for hypervolemia, hypernatremia, respiratory distress, elevated blood pressure.

Ernstmeyer & Christman, 2021

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Electrolytes

Ernstmeyer & Christman, 2021

Plays a key role in fluid regulation and healthy body functions.
Narrow range of “normal” values, even slight abnormality can have serious consequences.
Sodium
Potassium
Calcium
Phosphorus
Magnesium

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Sodium

Normal range: 135-145 mEq/L.
Most abundant electrolyte found in extracellular fluid (ECF).
Sodium-Potassium pump maintains levels of Sodium.
Key role in maintaining fluid balance between intravascular and interstitial spaces.
Hypernatremia (Sodium greater than 145 mEq/L).
Hyponatremia (Sodium less than 135 mEq/L).

Ernstmeyer & Christman, 2021

Contact info: info@nursesinternational.org

Hypernatremia is caused by excessive salt intake, or higher levels of sodium within the blood. This is achieved through a lack of fluid intake from the client, or vomiting or diarrhea. When there is an increase of salt in the blood, osmotic movement occurs moving the water out of the cells in order to dilute the blood. This occurrence causes the cells to shrink resulting in cellular dehydration. This can affect many vital organs because they are made up of cells. This can be most noticeable in the client’s cognitive function leading the client to be confused, irritable, lethargic, and potentially have seizures. Common signs of dehydration are also seen with hypernatremia such as dry sticky mucous membranes and thirst.

Hyponatremia can also be caused by excessive hypotonic solutions intravenously. Conversely, with hyponatremia, water moves into cells causing them to swell. Neurological symptoms may be seen as well, such as a headache, confusion, seizures, or even coma.

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Sodium

Ernstmeyer & Christman, 2021

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Potassium

Normal range: 3.5-5.1 mEq/L
Most abundant electrolyte found in the intracellular fluid
Sodium-Potassium pump also maintains potassium
Regulated by the kidneys and the release of aldosterone
Commonly consumed in dietary choices
Critical in cardiac functioning, neural functioning, and muscle contractility
Hyperkalemia (Potassium greater than 5.1 mEq/L)
Hypokalemia (Potassium less than 3.5 mEq/L)

Ernstmeyer & Christman, 2021

Contact info: info@nursesinternational.org

Common foods that aid in potassium consumption are oranges, bananas, and tomatoes.

Potassium is a key component in maintaining normal and healthy cardiac function and muscle contractility. Potassium levels outside of normal range can cause abnormalities in heart rhythms and contractility. Potassium is not conserved well by the body and is excreted in the urine. A nursing consideration of administering care to a client receiving loop or thiazide diuretics is to provide potassium supplements because potassium is commonly lost through excretion along with water. This supplement can be given either orally or through an intravenous infusion, but should never be given through IV push because this could stop the heart immediately.

The main signs of hyperkalemia are cardiac signs such as electrocardiogram abnormalities, which can then progress into more serious consequences such as cardiac dysrhythmias and cardiac arrest.

Kayexalate is a pharmacological intervention given for severe symptoms of hyperkalemia. This is given either orally or rectally and assists in binding excess potassium so that it is excreted through the gastrointestinal tract. In some instances, insulin may be administered to the client to assist in pushing potassium into the cells and therefore decreasing serum potassium levels. There are often accompanying medications that are given along with insulin to treat hyperkalemia such as IV dextrose and IV calcium gluconate. This is a temporary treatment to prevent cardiac muscle effects or arrest from high potassium.

Additional causes of hypokalemia involves an excess of vomiting or diarrhea, potassium-wasting diuretics, insulin use, or a lack of dietary consumption of potassium.

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Potassium

Ernstmeyer & Christman, 202

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Calcium

Normal range: 8.6-10.2 mg/dL
Calcium freely circulates in the blood but is mainly stored in bones
Key role in maintaining healthy bone and teeth structure, nerve transmissions, and muscle contractions
Parathyroid hormone (PTH), excreted by the parathyroid gland, regulates calcium excretion and reabsorption
Physical activity and dietary consumption impacts calcium levels
Hypercalcemia (calcium greater than 10.2 mg/dL)
Hypocalcemia (calcium less than 8.6 mg/dL)

Ernstmeyer & Christman, 2021

Contact info: info@nursesinternational.org

Low serum calcium → PTH secreted → calcium reabsorbed in kidneys and intestine while being released from bones → increased serum calcium

When a person is physically active, calcium moves into the bones. On the contrary, when a person is immobile, calcium is released from the bones causing weakness. Common forms of calcium that are present in a person’s diet include dairy products, vegetables, sardines, whole grains, and green leafy vegetables.

Prolonged immobility may cause hypercalcemia because the calcium exits the bones and is released into the serum. Examples of other causes that can cause hypercalcemia are hyperparathyroidism and a presence of a parathyroid tumor, causing too much PTH, therefore releasing too much calcium from the bones and absorbing it into the kidneys and intestine. Signs of hypercalcemia include typically affecting the gastrointestinal system or musculoskeletal system. Symptoms are outlined above in the image. Aside from decreasing calcium in the diet, administering phosphate supplementation can be performed because phosphorus has an inverse relationship with calcium. Weight bearing exercises may assist and also surgery to remove the parathyroid gland if hyperparathyroidism is causing the issue of hypercalcemia.

Hypocalcemia can be caused by hypothyroidism, where the parathyroid does not release enough PTH, therefore decreasing the the reabsorption of calcium and decreased calcium from the bones being released. Renal disease and a vitamin D deficiency can also cause hypocalcemia. Elevated phosphorus, as is commonly seen with renal failure, can affect the calcium numbers, and cause hypocalcemia. The nervous system and the musculoskeletal system are the two main systems involved in symptoms of hypocalcemia. Common symptoms are seen in the above image. Treatments often include increasing oral calcium, vitamin D, decreasing phosphorus, or giving IV supplements if necessary.

Chvostek’s sign: considered a “classic” sign of hypocalcemia. When the facial nerve is tapped, there is an involuntary twitching.

Trousseau’s sign: another “classic” sign of hypocalcemia. When inflating a blood pressure cuff to a level above the systolic pressure for 3 minutes, there is a hand spasm in the respective hand.

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Calcium

Ernstmeyer & Christman, 2021

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Phosphorus

Normal range: 2.5-4.0 mg/dL
Predominantly found in ICF, small amount in ECF, stored in bones
Key roles in: energy metabolism, nerve functioning, muscle contractions, forming RNA and DNA, building and repairing membranes, bone, and teeth
Excreted by the kidneys & absorbed by intestines
Commonly consumed through diet
Hyperphosphatemia (phosphorus over 4.0 mg/dL)
Hypophosphatemia (phosphorus under 2.5 mg/dL)

Ernstmeyer & Christman, 2021

Contact info: info@nursesinternational.org

Dairy products, vegetables, meat, cereal, and fruits provide dietary phosphorus.

Hyperphosphatemia, an increased phosphorus level, can be caused by excessive use of phosphorus containing enemas, a crush injury, or kidney disease. Symptoms are not often seen, but rather symptoms of hypocalcemia may be seen because of the inverse relationship between phosphorus and calcium. Treatment options may include a decreased oral intake of phosphorus, hemodialysis, and administering the client a phosphate-binder medication to increases excretion.

Hypophosphatemia may be caused by burns, acute alcohol abuse, starvation, diabetic ketoacidosis that is resolving, respiratory alkalosis, and the use of diuretics. This may also be seen chronically if a client presents with a vitamin D deficiency, hypomagnesemia, hypokalemia, the use of phosphate binders for an extended amount of time, and hyperparathyroidism. Unless severe hypophosphatemia is present, there are usually no symptoms. When the numbers are severely low, symptoms that can be present are muscle weakness, encephalopathy, seizures, anorexia, and even death. Treatment includes identifying and treating the underlying cause of hypophosphatemia. Often times, this includes oral or IV phosphorus replacements and increasing phosphorus rich foods in the diet.

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Magnesium

Normal range: 1.5-2.4 mEq/L
Key roles in: maintaining normal muscle, immune system, nerve, and cardiac functions
Half of magnesium found stored in bones, 1% in ECF and rest in ICF
Consumed through dietary sources
Hypermagnesemia (magnesium above 2.4 mEq/L)
Hypomagnesemia (magnesium below 1.5 mEq/L)

Ernstmeyer & Christman, 2021

Contact info: info@nursesinternational.org

Dietary sources of magnesium: citrus, peanut butter, legumes, chocolate, almonds, green leafy vegetables

Hypermagnesemia causes may be an excessive use of magnesium containing antacids or laxatives, overload of magnesium replacements, or renal failure. Aside from the symptoms listed in the image above, because it has a role in cardiac function, cardiac arrest may result. Treatments for hypermagnesemia include peritoneal dialysis or hemodialysis if the case is severe, as well as the treatments listed above. Calcium gluconate can also be given to help reduce any cardiac effects of the high magnesium levels until the level can be lowered.

Hypomagnesemia typically occurs from a lack of magnesium in the diet. Also, clients who have alcohol use disorder can exhibit hypomagnesemia because of the impaired nutrient absorption coupled with poor dietary choices. The use of a proton pump inhibitor chronically can impair nutrient absorption, leading to hypomagnesemia. Symptoms are listed in the image above, as well as treatments.

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Magnesium

Ernstmeyer & Christman, 2021

Contact info: info@nursesinternational.org

Dietary sources of magnesium: citrus, peanut butter, legumes, chocolate, almonds, green leafy vegetables

Hypermagnesemia causes may be an excessive use of magnesium containing antacids or laxatives, overload of magnesium replacements, or renal failure. Aside from the symptoms listed in the image above, because it has a role in cardiac function, cardiac arrest may result. Treatments for hypermagnesemia include peritoneal dialysis or hemodialysis if the case is severe, as well as the treatments listed above. Calcium gluconate can also be given to help reduce any cardiac effects of the high magnesium levels until the level can be lowered.

Hypomagnesemia typically occurs from a lack of magnesium in the diet. Also, clients who have alcohol use disorder can exhibit hypomagnesemia because of the impaired nutrient absorption coupled with poor dietary choices. The use of a proton pump inhibitor chronically can impair nutrient absorption, leading to hypomagnesemia. Symptoms are listed in the image above, as well as treatments.

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Case Study

The nurse is analyzing their client’s most recent blood draw. The client was admitted for gastroenteritis with symptoms of vomiting and diarrhea for multiple days, and is unable to eat or drink anything by mouth. The lab results indicate the following numbers: Sodium 124 mEq/L and Potassium 2.6 mEq/L. The nurses notes that the physician ordered the following: 0.9% Normal Saline infusion at 110 mL/hour, nothing by mouth, and strict inputs and outputs and daily weights be recorded.

Identify the abnormal results and common signs and symptoms that might be associated with each.

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Nursing Process for Fluid and Electrolyte Balances

Ernstmeyer & Christman, 2021

Daily weights

Assists in analyzing trends
May be beneficial to take more frequent weights

Example: every 8 hours

Closely monitor fluid inputs and outputs
Educate client about any dietary changes

Restrictions fluid or certain electrolyte rich food

Closely monitor for respiratory or cardiac function changes

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Reference:

Ernstmeyer, K., & Christman, E. (Eds.). (2021). Open RN Nursing Fundamentals. By Chippewa Valley Technical College, licensed under CC BY 4.0. https://wtcs.pressbooks.pub/nursingfundamentals/open/download?type=pdf

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