Fluid & Electrolyte Imbalance IV Fluid Therapy

Module 2B: Fluid & Electrolyte Imbalance and IV Fluid Therapy

Course Information

  • Instructor: Cathy Magowan, PhD, MSN, RN

  • Institution: D’Youville University

  • Course Code: NUR 320

  • Semester: Spring 2025

Learning Objectives

  • Compare and Contrast Membrane Transport Mechanisms:

    • Diffusion

    • Osmosis

    • Active Transport

    • Passive Transport

    • Endocytosis

    • Exocytosis

  • Verbalize: Understanding of fluid and electrolyte disorders.

  • Discuss: Diagnostic tests for fluid and electrolyte disorders.

  • Understand: Role of electrolytes in homeostasis and normal ranges of lab values of electrolytes.

  • Describe: Ways the body regulates blood pressure, including the RAAS system.

  • Describe: Diuretic agents' therapeutic action, contraindications, pharmacokinetics, adverse reactions, and drug-drug interactions.

  • Describe: Nursing actions, including patient education related to diuretic medications and fluid replacement therapy.

Terms to Know

  • Diffusion:

    • Process during which substances are dispersed until a uniform concentration is reached.

  • Osmosis:

    • Movement of water down the concentration gradient.

  • Active Transport:

    • Requires energy to move substances across a membrane.

  • Passive Transport:

    • Movement of substances across a membrane without the need for energy.

  • Exocytosis:

    • Process for secreting substances from inside a cell to the outside.

  • Endocytosis:

    • Process where cells surround and take in materials from their surroundings, which includes phagocytosis.

Plasma Membrane Role in Fluid and Electrolyte Movement

  • Structure:

    • Acts as a semipermeable barrier, determining entry and exit of substances.

    • Mainly composed of a lipid bilayer (phospholipids), serving as a barrier to all but lipid-soluble substances.

Mechanisms of Transport

  • Diffusion:

    • Movement of substances from higher concentration to lower concentration.

  • Osmosis:

    • Specific to the movement of water (not other substances).

  • Facilitated Diffusion:

    • Movement of substances with the assistance of proteins due to non-lipid solubility or size constraints.

  • Active Transport:

    • Energy-dependent transport of substances across membranes.

Fluid Distribution in the Body

  • Body Fluids Distribution:

    • Fluid distribution between intracellular fluid (ICF) and extracellular fluid (ECF).

    • Intracellular Fluid (ICF) Composition:

    • High in Potassium (K)

    • Moderate in Magnesium (Mg)

    • Small amounts of Calcium (Ca), Sodium (Na), Chloride (Cl), Bicarbonate (HCO3), and Phosphorus (P).

    • Extracellular Fluid (ECF) Composition:

    • High in Sodium (Na) and Chloride (Cl)

    • Moderate Bicarbonate (HCO3) and small amounts of Calcium (Ca), Magnesium (Mg), and Phosphorus (P).

Normal Lab Values of Electrolytes

  • Sodium (Na): 135 to 145 mEq/L

  • Potassium (K): 3.5 to 5.0 mEq/L

  • Calcium (Ca): 8.5 to 10.5 mg/dL

  • Chloride (Cl): 98 to 106 mEq/L

  • Magnesium (Mg): 1.8 to 3.0 mg/dL

  • Phosphorus (P): 2.5 to 4.5 mg/dL

  • Bicarbonate (HCO3): 24 to 31 mmol/L

Tonicity

  • Hypertonic:

    • Higher solute concentration outside the cell.

    • Water moves out, leading to cell shrinkage.

  • Isotonic:

    • Equal solute concentrations inside and outside the cell.

    • No net movement of water.

  • Hypotonic:

    • Higher solute concentration inside the cell, leading to water moving in and cell swelling.

Body Fluid Distribution - Age Considerations

  • Total Body Water (TBW):

    • Varies in amounts among different populations:

    • In pediatrics, TBW is 75% to 80% of body weight, making them susceptible to significant fluid changes.

    • Aging results in decreased TBW percentage due to increased adipose tissue and decreased muscle mass, renal decline, and diminished thirst perception.

Capillary-Interstitial Fluid Exchange

  • Capillary filtration pressure:

    • Pushes water out of the capillary.

  • Capillary colloidal osmotic pressure:

    • Pulls water back into the capillary.

  • Interstitial hydrostatic pressure:

    • Aims to retain water inside the capillary.

  • Tissue colloidal osmotic pressure:

    • Pulls water out of the capillary.

Edema Causes

  • Increased Capillary Pressure:

    • Includes causes like heart failure, kidney disease, pregnancy, and venous obstruction.

  • Decreased Colloidal Osmotic Pressure:

    • Associated with protein loss due to various diseases, extensive burns, liver disease, and malnutrition leading to hypoproteinemia.

Hypervolemia (Fluid Volume Excess)

  • Causes:

    • Inadequate sodium and water elimination, heart failure, renal failure, corticosteroid levels increase, excessive sodium intake, IV fluid overload.

  • Characteristics/Symptoms:

    • Sudden weight gain, edema, distended neck veins, full bounding pulse, increased blood pressure, shortness of breath, respiratory crackles, ascites, or pleural effusion if severe.

Diuretic Therapy Overview

  • Classification of Diuretics:

    • Thiazide Diuretics

    • Loop Diuretics

    • Carbonic Anhydrase Inhibitors

    • Potassium-Sparing Diuretics

    • Osmotic Diuretics

    • Indications for Use:

    • Management of edema associated with heart failure, acute pulmonary edema, liver disease, renal disease, and hypertension.

Specific Diuretic Details

  • Thiazide/Thiazide-like Diuretics:

    • Prototype: Hydrochlorothiazide

    • Major action site: Distal convoluted tubule

    • Common adverse effects: GI upset, CNS issues, electrolyte alterations.

  • Loop Diuretics:

    • Prototype: Furosemide (Lasix)

    • Major action site: Loop of Henle

    • Adverse effects: Hypokalemia, volume depletion, hypotension, ototoxicity.

  • Carbonic Anhydrase Inhibitors:

    • Prototype: Acetazolamide (Diamox)

    • Major action site: Proximal tubule

    • Indications: Glaucoma and certain forms of edema.

  • Potassium-sparing Diuretics:

    • Prototype: Spironolactone

    • Major action site: Distal tubule and collecting duct

    • Adverse effects: Hyperkalemia.

  • Osmotic Diuretics:

    • Prototype: Mannitol (Osmitrol)

    • Sites action: Glomeruli and renal tubules

    • Adverse effects: Hypotension, CNS toxicity.

Hypovolemia (Fluid Volume Deficit)

  • Causes:

    • Inadequate fluid intake, excessive fluid losses (vomiting, diarrhea), and diuretic therapy.

  • Characteristics/Symptoms:

    • Elevated heart rate, weak pulses, low blood pressure, dry skin and mucous membranes, concentrated urine.

IV Hydration Solutions

  • Hypertonic:

    • Examples: 3% Saline, 5% Saline

    • Indications: Treatment of sodium and chloride depletion.

  • Hypotonic:

    • Example: 0.45% Normal Saline

    • Indications: Hydrating solution for kidney function evaluation.

  • Isotonic:

    • Example: 0.9% Normal Saline

    • Indications: Fluid, sodium, and chloride replacement.

Electrolyte Imbalance Overview

Potassium Imbalance

  • Hyperkalemia:

    • Normal Levels: 3.5-5 mEq/L

    • Causes: Cellular movement of K+, renal failure, excess intake, certain drugs.

    • Signs & Symptoms grouped mnemonic: "Murder"

    • Muscle weakness

    • Urine output diminished

    • Respiratory failure

    • Decreased cardiac contractility

    • Early twitching/cramps

    • Rhythm changes (tall T waves, prolonged PR interval)

  • Hypokalemia:

    • Normal Levels: 3.5-5 mEq/L

    • Causes: Loop diuretics, loss via vomiting/diarrhea

    • Signs & Symptoms grouped mnemonic: "7 L's (low)"

    • Lethargy

    • Low, shallow respirations

    • Lethal dysrhythmias

    • Lots of urine

    • Leg cramps

    • Limp muscles

    • Low blood pressure

Sodium Imbalance

  • Hypernatremia:

    • Signs & Symptoms grouped mnemonic: "FRIED & SALTED"

    • Fever

    • Restlessness

    • Increased fluid retention

    • Edema

    • Dry mouth

    • Acute/severe symptoms can include confusion and seizures.

Other Electrolytes
Magnesium

  • Normal Range: 1.3-2.1 mEq/L

  • Hypermagnesemia Symptoms: High BP, bradycardia.

  • Hypomagnesemia Symptoms: Low BP, muscle weakness.

Calcium

  • Hypocalcemia Symptoms: Tetany, muscle spasms, Chvostek's and Trousseau's signs.

  • Hypercalcemia Symptoms: Muscle weakness, severe thirst, psychiatric symptoms.

Chloride

  • Normal Range: 96-106 mEq/L

  • Imbalances: Can lead to hyperactive reflexes, symptoms of electrolyte changes, and respiratory issues.

Phosphate

  • Hyperphosphatemia Causes: Renal failure, hypoparathyroidism, vitamin D intoxication.

  • Hypophosphatemia Causes: Decreased intestinal absorption, urinary losses. Symptoms include muscle weakness and confusion.

Practice Questions

Question 1

  • The nurse has administered a diuretic to a client that acts to block the chloride pump in the distal convoluted tubules and leads to a loss of sodium and potassium and a minor loss of water. What type of diuretic was administered?

    • A) Carbonic anhydrase inhibitor

    • B) Osmotic diuretic

    • C) Potassium-sparing diuretic

    • D) Thiazide diuretic

Question 2

  • A client diagnosed with glaucoma has been prescribed a diuretic. What drug does the nurse suspect will be prescribed?

    • A) Acetazolamide

    • B) Spironolactone

    • C) Chlorthalidone

    • D) Torsemide

Question 3

  • What statement by the client indicates understanding of the nurse’s teaching about diuretics?

    • A) “I will weigh myself daily and report significant changes.”

    • B) “I will have to limit my high sugar foods.”

    • C) “If my leg becomes swollen again, I’ll take an additional pill.”

    • D) “I will take my medication before bedtime on an empty stomach.”

Question 4

  • What classification of diuretics should be expected as first-line therapy for essential hypertension?

    • A) Loop diuretics

    • B) Carbonic anhydrase inhibitors

    • C) Thiazide diuretics

    • D) Potassium-sparing diuretics

Question 5

  • A client prescribed spironolactone reports decreased urination. What would be an appropriate question for the nurse to ask?

    • A) “Are you taking a salicylate?”

    • B) “Are you taking acetaminophen?”

    • C) “Are you taking ibuprofen?”

    • D) “Are you adding extra salt to your food?”