Fluid and Electrolytes Flashcards

Fluid and Electrolytes

Process of Regulating:

• The body meticulously regulates several factors to maintain homeostasis, which includes:

  • Extracellular Fluid Volume: Important for maintaining blood pressure and ensuring adequate perfusion to organs.

  • Body Fluid Osmolality: This reflects the concentration of solutes in body fluids and influences fluid movement across cell membranes.

  • Plasma Concentrations of Electrolytes: Essential for normal cellular function, nerve impulse transmission, and muscle contraction.

Electrolytes are charged particles that dissociate in water, playing crucial roles in a variety of bodily functions.

• Examples:

  • Sodium (Na): Primarily found in extracellular fluid and crucial for regulating blood volume and pressure.

  • Potassium (K): The main intracellular electrolyte necessary for muscle contractions and nerve signaling.

  • Magnesium (Mg): Involved in over 300 enzymatic reactions in the body, including ATP production.

  • Calcium (Ca): Vital for bone health, muscle function, and neurotransmitter release.

Maintaining Balance:

• The body maintains fluid and electrolyte balance through several interactive mechanisms that include:

  • Intake and Absorption: Fluid and electrolytes are absorbed through various routes to maintain adequate levels in the body.

  • Distribution: Distribution mechanisms ensure that fluids and electrolytes are available where needed in the body.

  • Output: The body regulates how much fluid and electrolytes are excreted, ensuring homeostasis is maintained.

Fluid Compartments:

• Fluid is distributed in the body in two main compartments:

  • Intracellular Fluid (ICF): The fluid inside cells, which accounts for approximately two-thirds of total body water.

  • Extracellular Fluid (ECF): This includes:

  • Interstitial Fluid: Fluid that surrounds individual cells.

  • Vascular Fluid: Fluid within blood vessels, crucial for transporting nutrients and waste products.

Intake and Absorption:

• Routes of intake can significantly affect fluid and electrolyte balance, including:

  • Oral: The most common route, where food and fluids are ingested and absorbed in the gastrointestinal (GI) tract.

  • IV (Intravenous): Provides fluids and electrolytes directly into the bloodstream, bypassing absorption requirements.

  • Rectal: Used for administering fluids in specific situations, such as severe dehydration.

  • NG (Nasogastric Tube): Assists in nutritional support and fluid management in patients who cannot swallow.

All routes of intake except IV require absorption into the bloodstream, which occurs mainly in the intestines.

Absorption:

• The absorption of electrolytes occurs in different parts of the digestive system:

  • Calcium: Absorbed primarily in the duodenum, influenced by the presence of Vitamin D, which enhances its absorption.

  • Magnesium: Taken up in the intestinal epithelium and is critical for maintaining various metabolic functions.

Distribution:

• Fluid distribution involves several processes that maintain balance between compartments:

  • Filtration: This process helps in distributing extracellular fluid (ECF) between vascular and interstitial compartments.

  • Osmosis: Regulates water distribution between the ECF and cells, influencing hydration status.

  • Hydrostatic Pressure: Drives fluid out of the capillaries into interstitial spaces.

  • Colloid Osmotic Pressure: Helps draw fluid back into the capillaries from the interstitial space.

Electrolyte Distribution:

• Electrolytes have specific locations within the body:

  • Sodium (Na) is primarily extracellular, critical for fluid balance and neuronal activity.

  • Potassium (K) is mainly intracellular, essential for cellular functions and cardiac health.

  • Calcium (Ca) chiefly resides in bones but plays important roles in muscle contraction and neurotransmission.

  • Magnesium (Mg) is found in cells and bones and is important for many biochemical reactions.

Output:

• The body has several routes for output, leading to electrolyte and fluid loss, including:

  • Feces: A minor route for fluid loss under normal conditions.

  • Sweat: Helps regulate body temperature but also contributes to electrolyte loss, particularly sodium and chloride.

  • Urine: The largest route of fluid and electrolyte excretion under normal circumstances, regulated primarily by the kidneys.

  • Lungs: Water vapor is lost during respiration, contributing to total fluid loss.

Aldosterone:

• This hormone is secreted in response to Angiotensin II, primarily influencing:

  • Sodium and Water Retention: Acts on the renal tubules to reabsorb sodium and subsequently water, thereby increasing extracellular volume (ECV).

  • Potassium Excretion: Facilitates the excretion of potassium, crucial for maintaining electrolyte balance.

  • Imbalances to Monitor:

  • Hypernatremia: Elevated sodium levels can lead to cellular dehydration.

  • Hypokalemia: Low potassium levels can cause cardiac dysrhythmias and muscle weakness.

Antidiuretic Hormone (ADH):

• Regulates water excretion by the kidneys rather than sodium. Its effects include:

  • Increased ADH Levels: Lead to retention of water, making urine concentrated.

  • Decreased ADH Levels: Result in increased urine output, potentially leading to dehydration.

Young and Old:

• Infants: Assessing thirst and hydration status can be challenging; they have a higher percentage of extracellular fluid than adults, affecting their hydration needs.

• Older Adults: Have diminished renal reserve due to a reduced number of nephrons, making them more susceptible to dehydration. Strategies for assessing hydration status are crucial in this demographic.

ECF, Osmolality, Electrolyte Imbalance:

• ECF Imbalance: May reflect abnormal fluid volumes in the extracellular space, impacting perfusion and organ function.

  • Isotonic Fluid: Maintains balance when used for rehydration, as it has the same concentration as body fluids, ensuring sodium holds water effectively within the extracellular compartment.

• Osmolality Imbalance: Refers to changes in the concentration of body fluids related to sodium levels:

  • Hypernatremia: Occurs when body fluids are too concentrated; may result from excessive loss of water relative to sodium.

  • Hyponatremia: Happens when body fluids are too dilute, potentially leading to cellular swelling.

• Electrolyte Imbalances: Result from abnormal plasma concentrations:

  • Hypo-: Refers to too low levels, while Hyper-: Refers to too high levels, affecting various bodily functions.

Causes of Electrolyte Imbalances:

• Imbalances can arise from multiple situations:

  • Output greater than intake and absorption: Can lead to deficits, such as hypokalemia or hypomagnesemia.

  • Increased output: Without corresponding intake can occur during events like diarrhea or excessive sweating.

  • Output less than intake and absorption: Such as during excessive IV fluid administration or substantial sodium and water intake.

  • Altered distribution: Fluid shifts can cause edema or electrolyte distribution issues.

Consequences of Disruption of Fluid and Electrolytes:

• Disruptions can severely impact physiological functions:

  • Impaired Perfusion and Oxygenation: Reduced blood volume can lead to inadequate perfusion of tissues.

  • Impaired Cerebral Function: Sodium imbalances can affect neurological status.

  • Impaired Neuromuscular Function: Calcium and magnesium levels directly impact muscle contraction and nerve signaling.

  • Cardiac Dysrhythmias: Potassium imbalances can lead to arrhythmias, which can be life-threatening.

Primary and Secondary:

• Primary Prevention: Centers on teaching about rehydration strategies and identifying at-risk individuals to intervene early.

• Secondary Prevention: Involves screening for imbalances through lab tests and regular monitoring to manage risks effectively.

Nursing Interventions:

• Focus on hydration strategies to correct or prevent imbalances, addressing both intake and output of fluids and electrolytes, while considering individual patient needs and conditions.