LPN IV Series: Homeostasis and Regulatory Functions Relationship to IV Therapy

Our bodies maintain equilibrium through many processes. One of these processes involves homeostasis, which will be discussed in detail. Electrolytes also have a crucial role in our body by ensuring our levels are balanced, and our cells, nerves, and muscles function as they should. Many of these electrolytes and what can happen if they are not balanced will be discussed. One way to ensure we are hydrated and keep our bodies in check is hydration. When hydration is limited, we can replenish through intravenous (IV) fluids. We must use the correct fluid type based on the patient's need and condition.

Homeostasis is the steady state of the body by which the body's internal systems maintain a balance. It is maintained by adaptive responses that promote healthy functioning of the body.

One of the primary objectives of IV therapy is to maintain or restore the fluid and electrolyte balance in the body. Our bodies are composed mainly of fluid. These fluids will account for about 60% of the total body weight in an adult male and 45-50% in an adult woman. In infants, fluids account for about 80% of the total body weight and will steadily decrease throughout childhood until it reaches adult percentages at around eight years old.

Body fluids are composed of water and solutes. Solutes are classified as either electrolytes or nonelectrolytes. The nonelectrolytes are solutes without an electrical charge, including glucose, proteins, lipids, oxygen, carbon dioxide, and organic acids. The electrolytes will be discussed later.

Fluids help:

• regulate the body's temperature
• transport nutrients and gases throughout the body
• carry cellular waste products to excretion sites

The body fluids are distributed between two major compartments: intracellular fluid (ICF) inside the cells and extracellular fluid (ECF) outside the cells.

The ECF occurs in two forms: interstitial fluid surrounding each cell and lymph gland: and intravascular fluid, which is blood plasma. The interstitial fluid comprises the cerebrospinal, pleural, peritoneal, or synovial fluids and the secretions from the salivary glands, pancreas, liver, and sweat glands. The distribution of fluids between these two compartments is constant when the body is healthy. The heart, kidneys, liver, adrenal and pituitary glands, and nervous system all play a part in maintaining fluid balance in the body.

Fluid accumulation in a compartment other than the intracellular or extracellular space is third-space fluid shifting. The accumulation happens when a cellular membrane allows water and fluid to enter but not exit. For example, fluids pool in a burn site with severe burns, causing depletion of the ICF and ECF. If pancreatitis fluids "leak out" into the peritoneal cavity, this causes depletion of the ICF and ECF. Patients undergoing long and extensive surgeries will collect third-space fluids and become intravascularly depleted despite administering large volumes of IV fluids and blood. Third-space fluid shifting can also occur due to acute bowel obstruction, ascites, and sepsis. These patients will experience tachycardia, hypotension, weight gain, low urine output, poor skin turgor, and hyponatremia.

Fluid balance is also affected by the following:

• fluid volume
• distribution of fluids in the body
• the concentration of solutes in the fluid

The distribution of fluids depends on the hydrostatic and colloid osmotic pressures in the capillaries. Fluid volumes and concentration are regulated by interacting with two hormones, antidiuretic hormone (ADH) and aldosterone.

ADH is secreted when plasma osmolarity increases or circulating blood volume decreases, and blood pressure drops. ADH restores blood volume by reducing diuresis and increasing water retention.

Aldosterone is secreted when the serum sodium level is low, the potassium level is high, or the circulation volume of fluid decreases. It causes the kidneys to retain sodium and water.

Osmolarity is the concentration of a solution. Usually, the serum has the same osmolarity as other body fluids, approximately 300 mOsm/L. If your patient has a lower serum osmolarity, they may have a fluid overload. A higher serum osmolarity indicates the patient may be experiencing hemoconcentration of the fluid and dehydration.

Body fluids are in constant motion moving between the fluid compartments through membranes. Homeostasis is maintained when the solutes and fluids are distributed evenly on each membrane. When there is an imbalance, these molecules will move between the compartments by various routes, including:

• In diffusion, molecules move from areas of higher concentration to areas of lower concentration.
• Active transport requires energy for molecules to move from areas of lower concentration to areas of higher concentration. These molecules are moved by physiologic pumps (sodium-potassium pumps).
• With passive transport, solutes are affected by the electrical potential across cell membranes.
• Filtration is the movement of substances from an area of high hydrostatic pressure to an area of lower hydrostatic pressure.
• Capillary filtration forces fluid and solutes through capillary wall pores.
• Osmosis fluids flow passively from an area of higher water concentration to an area of lower concentration. The process stops when the solute concentrations on both sides of the membrane are equal. The body responds to osmolality changes because of osmotic and hydrostatic pressures (Nettina, 2019).

As discussed above, fluid is essential for our body. It has many different functions, our body depends on it, and the actions of fluid depend on our intake and excretion.

Just as there are types of dehydration, there are different types of IV fluids often used to replenish a loss.

Three basic types of fluids are utilized for IV therapy. They are:

1. Isotonic
2. Hypotonic
3. Hypertonic

Isotonic fluids have the same osmolality as serum and other body fluids (Nettina, 2019). It expands the intravascular compartment. It can treat hypotension secondary to hypovolemia or as maintenance fluids.

Isotonic fluids include:

• 2.5% dextrose/0.45% sodium chloride
• 0.9% sodium chloride (normal saline)
• 5% dextrose and water
• Normosol® R
• Plasmalyte® A
• Plasmalyte® R
• lsolyte® 4 E · Ringer's
• Lactated Ringer's
• 2.5% dextrose in 1/2 lactated Ringer's
• 6% dextran and 0.9% sodium chloride
• 10% dextran and 0.9% sodium chloride

Hypotonic fluids have a lower osmolality than the serum (Nettina, 2019). When given, they help hydrate the cells and can decrease the amount of fluid in the circulatory system. Hypotonic fluids are used when diuretic therapy dehydrates the cells to lower serum sodium levels, treat diabetic ketoacidosis, and treat hyperglycemic nonketotic syndrome.

Hypotonic fluids include:

• 0.45% normal saline (half-normal saline)
• 0.33% normal saline (one-third saline)
• D2.5W (dextrose 2.5% in water)

Hypertonic solutions have a higher osmolality than the serum (Nettina, 2019). These fluids pull fluid back into the blood vessels from the interstitial and intracellular compartments. It can treat hypovolemia and low serum sodium levels or help reduce the risk of edema and low blood pressure in postoperative patients.

Hypertonic fluids include:

• 5% dextrose/0.2% sodium chloride
• 5% dextrose/0.3% sodium chloride
• 5% dextrose/0.45% sodium chloride
• 5% dextrose/0.9% sodium chloride
• 10% dextrose/0.2% sodium chloride
• 10% dextrose/0.45% sodium chloride
• 10% dextrose/0.9% sodium chloride
• 3% sodium chloride
• 5% sodium chloride
• 10% dextrose and water
• 50% dextrose and water
• 5% dextrose in Ringer's
• 5% dextrose in lactated Ringer's
• 5% dextrose and 5% alcohol
• 5% sodium bicarbonate injection
• 10%, 15%, and 20% mannitol injection
• 6% dextran and 0.9% sodium chloride
• 10% dextran and 0.9% sodium chloride

Electrolytes help to keep our bodies functioning properly. Electrolytes help our muscles contract and assist with chemical reactions like fluid balance. Electrolytes can be either positive or negative; they can conduct electricity when dissolved in a liquid. For example, sodium and chlorine are oppositely charged, and when together, they even each other out.

Electrically-charged ions are positive ions or cations, and negative ions are called anions.

Electrolytes help to maintain homeostasis and balance within the body. Our bodies use ions and electrolytes to help move chemical compounds between cells (Cleveland Clinic, 2021).

As we learned above, electrolytes play critical roles in the body. Electrolyte imbalances occur when the level of electrolytes in the body is not within their specified ranges. Any imbalance can create significant issues for the patient, including life-threatening symptoms.

Hypernatremia: Hypernatremia means there are excess amounts of sodium in the body. Severe volume loss and depletion can cause hypernatremia. However, the most common cause of hypernatremia is osmotic diuresis, often seen in patients diagnosed with diabetes. Patients with kidney disease are at risk of hypernatremia if the kidneys cannot concentrate the urine.

Patients with hypernatremia will experience thirst. However, extreme symptoms of hypernatremia are possible, depending on the extent of the condition. Adults may experience confusion, seizures, comas, hyperreflexia, and muscle excitability. Children may experience brain bleeds and thrombotic events (Lewis, 2022c).

Hyponatremia: Hyponatremia occurs when there is a lack of sodium in the body. At times, low sodium can be caused by an excess of other substances in the body, such as glucose or sugar. Patients with hyponatremia will experience central nervous system dysfunction. Older adults tend to experience more symptoms than younger adults. Altered mental status, altered personality, coma, seizures, muscle hyperexcitability, and even death can occur (Lewis, 2022d).

Hyperkalemia: Hyperkalemia occurs when the body has high amounts of potassium. Potassium is often found in many of the foods we eat and supplements we take. Even though potassium is helpful and necessary for our bodies, having too much potassium is very dangerous for the heart.

The most common causes of high potassium include the following:

• Kidney damage and disease: One of the jobs of the kidney is to balance potassium levels between intake, such as food, and output with urination. When severely damaged or diseased, the kidneys cannot remove potassium, leading to excess buildup. The most common cause of hyperkalemia is chronic and advanced kidney disease.
• Other causes of hyperkalemia include overeating food high in potassium, such as bananas, orange juice, cantaloupe, and honeydew melon. Medications can also cause high potassium in the body. Some medications prevent the kidneys from removing potassium.

Mild symptoms of hyperkalemia include tingling, nausea, muscle weakness, and paresthesia. These symptoms can be mild to severe and can progress. If severe, hyperkalemia can progress into problems such as arrhythmias and heart attacks (Simon et al., 2022).

Hypokalemia: Hypokalemia is the opposite of hyperkalemia and occurs when the body has a low potassium level, less than 3.5 mEq/L. Anything less than 2.5 mEq/L is considered to be severe and can be life-threatening. Hypokalemia usually occurs from a lack of potassium intake, a shift of potassium in the body to inside the cells, and increased potassium excretion.

Symptoms of hypokalemia include the following:

• Worsening diabetes
• Polyuria
• Weakness
• Fatigue
• Palpitations
• Pain/muscle cramps
• Depression
• Delirium, psychosis, and/or hallucinations (Kim et al., 2023)

Hyperchloremia: Hyperchloremia occurs when there is excess chloride in the blood. A chloride imbalance can also cause dehydration as chloride helps to maintain fluid balance.

Patients may not experience symptoms until chloride levels are high for an extended period of time. When symptoms are experienced, they include the following:

• High blood pressure
• Seizures
• Retention of fluid
• Arrhythmias
• Muscle twitches
• Weakness
• Confusion
• Personality changes
• Numbness and tingling (Cafasso, 2018)

Hypochloremia: Hypochloremia is when there is a low level of chloride in the blood, this would be a level lower than 97 mEq/L.

Kidney problems often cause chloride imbalances.

Chloride imbalances often do not show signs and symptoms unless they are extreme. When patients do experience symptoms, they usually experience:

• Fluid loss
• Dehydration
• Diarrhea
• Vomiting (Seladi-Schulman, 2018)

Hypercalcemia: Hypercalcemia occurs when there is excess calcium in the blood. It can be mild to severe and temporary or chronic. As discussed above, parathyroid hormone and calcitonin assist with controlling the level of calcium in the body. Vitamin D is also essential in maintaining adequate levels of calcium. Acute and temporary hypercalcemia may not produce symptoms. However, with long-term and severe hypercalcemia, patients often experience the following:

• Fatigue
• Constipation
• Loss of appetite
• Headaches
• Bone pain
• Gastrointestinal upset (Lewis, 2022b)

Hypocalcemia: Hypocalcemia results when there are low calcium levels in the blood, usually less than 8.8 mg/dL. There are many causes of hypocalcemia, including renal disease, hypoparathyroidism, and vitamin D deficiency.

Symptoms of hypocalcemia include:

• Seizures
• Paresthesia
• Heart failure
• Tetany (Fong & Khan, 2012)

Hyperphosphatemia: High phosphate levels in the blood are called hyperphosphatemia, and it is often a sign of kidney damage. High phosphate levels may not cause problems, but it can cause low calcium, which results in symptoms such as muscle pain and weak bones (Goyal & Jialal, 2022).

Hypophosphatemia: Hypophosphatemia occurs when there are low phosphate levels in the blood. Hypophosphatemia can be mild to severe and acute or long-term.

Long-term hypophosphatemia can include the following symptoms:

• Seizures
• Altered mental status
• Muscle pain
• Fatigue
• Weakness
• Irritability (Sharma et al., 2022)

Hypermagnesemia: Hypermagnesemia results when there are excess magnesium levels in the blood. It is uncommon to see; if seen, patients may experience nausea, vomiting, and headaches. Common causes of hypermagnesemia include the following:

• Lithium intake
• Addison's disease
• Hypothyroidism
• Depression
• Familiar hypercalcemia (Cascella & Vaqar, 2022)

Hypomagnesemia: Hypomagnesemia is when there are low levels of magnesium in the body. It can be mild or severe and usually occurs with low calcium and potassium levels.

Symptoms of mild hypomagnesemia include:

• Fatigue
• Weakness
• Tremors
• Muscle spasms or cramps
• Nystagmus or abnormal eye movements

Symptoms of severe hypomagnesemia include:

• Arrhythmias
• Seizures
• Delirium (Ahmed & Mohammed, 2019)

Sharon is a 60-year-old female who presented to the emergency department with shortness of breath for the past four days. Sharon has a history of high blood pressure, stage 3 chronic kidney disease, and diabetes. Sharon's son, Jeremy, is present and tells the nurse that his mom is always winded, no matter what she does. She even experiences shortness of breath while resting lately. Jeremy also tells the nurse that his mother has been extremely lethargic for the past two days. Also, Sharon has been experiencing severe cramping in both legs for the past few days. She requires nearly total assistance with daily and routine activities.

Sharon was in the hospital six weeks ago for her chronic kidney disease; since then, she has continued to experience further medical problems.

She has been on 1.5L of oxygen via nasal cannula since her discharge from the hospital. One week ago, her dose of Lasix was doubled as she is experiencing increased kidney problems and now heart trouble.

Sharon appears alert and oriented to person, place, and time with no neurological deficit. However, she is in respiratory distress. She relies on her accessory muscles to assist with breathing and has difficulty completing sentences without stopping for air. Her vital signs show tachycardia, tachypnea, hypotension, and hypoxia.

The nurse and provider of care decide labs should be drawn.

Serum potassium: 2.4 mEq/L

Magnesium 1.3 mEq/L

During her physical exam, her abdomen was soft and non-distended. Pulses in the lower extremity were diminished bilaterally to +1.

The physician makes the following impressions:

• Acute hypoxic respiratory failure secondary to pulmonary edema
• Congestive heart failure
• Hypokalemia and hypomagnesemia secondary to diuretics (her Lasix)

Impairments include the following:

• The patient is lethargic and has difficulty breathing on minimal exertion (appears winded at rest).
• The patient exhibits a decrease in overall muscle strength.

Activity limitations include the following:

• The patient is unable to ambulate due to weakness and fatigue.
• The patient cannot complete a simple task due to fatigue and respiratory distress.

Based on the patient's subjective and objective findings, Sharon's cardiopulmonary complications and co-morbidities (kidney disease) have led to congestive heart failure, hypomagnesemia, and hypokalemia. The targeted interventions include replacing potassium via IV and monitoring for other possible electrolyte imbalances. The patient's diuretics should be monitored since they may lead to unwanted side effects. The goal is to make the patient euvolemic, and if the patient cannot do so with diuretics, a nephrologist should be consulted for possible hemodialysis. Upon discharge, the patient will need potassium supplements following her diuretic therapy. Labs will need to be rechecked in one week, and the patient should be referred to a heart failure specialist.

In one week, Sharon got her labs rechecked, and it was determined that her electrolyte levels were now within normal range. Sharon and the family know what symptoms to look for and to get labs checked frequently.

It is natural for our bodies to seek balance and homeostasis. Homeostasis is the steady state of the body. It is maintained by adaptive responses that promote healthy functioning of the body. Some of these adaptive processes occur when there is an imbalance of electrolytes or fluid.

Our bodies are made up of a lot of water and fluid. Fluids help regulate the body's temperature, transport nutrients and gases and carry cellular waste products to excretion sites. Fluid is very important and can easily be affected. Fluid balance is affected by fluid volume, the distribution of fluids in the body, and the concentration of solutes in the fluid.

One surefire way to ensure fluid balance in the body is by maintaining an adequate fluid intake. A healthy adult should drink around two liters of fluids daily. If the body is healthy and not diseased, water and fluid excretion occur through urination and natural losses. Fluid volume overload can happen if we drink too much or our body holds on to too much water. Losing too much fluid is called a fluid volume deficit, and patients can easily become dehydrated. Hypotonic or hyponatremic dehydration occurs when sodium loss exceeds water loss, decreasing serum osmolality. Hypertonic or hypernatremic dehydration occurs when water excretion from the body exceeds sodium excretion. Isotonic or isonatremic dehydration occurs when sodium and water are lost.

Just as important as fluid is electrolytes. Common electrolytes include sodium, potassium, magnesium, phosphate, and chloride. Each electrolyte imbalance has its own causes, symptoms, and interventions. For example, sodium helps to maintain blood pressure and acid-base balances. When patients experience gastrointestinal upset, such as excessive vomiting and diarrhea, sodium loss or hyponatremia can occur. With hyponatremia, patients may experience further symptoms of irritability, fatigue, muscle weakness, tachycardia, headache, and hypotension. To fix the sodium imbalance, we must treat this underlying problem. Patients with gastrointestinal upset may not feel like eating and drinking. Therefore, patients may need IV hydration. Nurses must be careful when administering IV hydration to patients with heart or kidney failure. As you can see, each imbalance is unique to the patient, and interventions or treatments depend on the underlying cause of the imbalance and the condition and status of the patient.

It is our job as nurses and providers of care to ensure we take adequate histories from the patient to determine what is truly going on. Patients may be working out in extreme temperatures or accidentally taking too many over-the-counter vitamins. Patients can sometimes forget to keep up with their intake, which is often seen in dementia and Alzheimer's. It can be easy to overlook an electrolyte or fluid imbalance until the patient is experiencing symptoms; sometimes, those symptoms can be severe or life-threatening.

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