Fluid and Electrolytes Lecture Notes Review

Composition and Movement of Body Fluids

• Total Body Water (TBW): Represents the sum total of fluid within all body compartments.

• Fluid Compartments:     * Intracellular Fluid (ICF): Fluid located inside the cells.     * Extracellular Fluid (ECF): Fluid located outside the cells, subdivided into:         * Interstitial Fluid: Fluid between cells and outside the blood vessels.         * Intravascular Fluid: Blood plasma.         * Transcellular Fluid: Fluids like cerebrospinal, pleural, peritoneal, and synovial fluids.

• Constituents of Fluids:     * Solutes: Substances dissolved in a liquid.     * Crystalloids: Small particles (e.g., salts, sugars) that can pass through semi-permeable membranes.     * Colloids: Large particles (e.g., proteins like albumin) that cannot pass through semi-permeable membranes.     * Electrolytes: Charged particles (ions).     * Nonelectrolytes: Uncharged particles (e.g., glucose, urea).

• Mechanisms of Fluid and Solute Movement:     * Osmosis: The movement of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.     * Diffusion: The movement of solutes from an area of higher concentration to an area of lower concentration.     * Filtration: The movement of water and solutes across a membrane due to hydrostatic pressure.     * Active Transport: The movement of electrolytes across cell membranes against a concentration gradient, requiring energy (ATP).

• Measurement of Concentration:     * Osmolality: Concentration of solutes per kilogram of solvent.     * Osmolarity: Concentration of solutes per liter of solution.     * Tonicity: The ability of an extracellular solution to make water move into or out of a cell by osmosis.     * Osmotic Pressure (Oncotic Pressure): The pressure exerted by colloids (proteins) that pulls water into the circulatory system.

Fluid Classifications and Tonicity

• Hypotonic Solutions:     * Fewer particles relative to fluid (\text{fewer particles} < \text{fluid}).     * Causes water to move into the cells, potentially causing them to swell.

• Isotonic Solutions:     * Equal concentration of particles and fluid ($\text{particles} = \text{fluid}$).     * No net movement of water; maintains equilibrium.

• Hypertonic Solutions:     * More particles relative to fluid (\text{more particles} > \text{fluid}).     * Causes water to move out of the cells, potentially causing them to shrink.

• Volume States:     * Hypervolemic: Excessive fluid volume relative to particles.     * Hypovolemic: Deficient fluid volume relative to particles.

Electrolyte Regulation and Ranges

• Electrolyte Types:     * Major Cations (Positive Charge):         * Sodium ($Na^{+}$)         * Magnesium ($Mg^{2+}$)         * Potassium ($K^{+}$)         * Calcium ($Ca^{2+}$)         * Hydrogen ($H^{+}$)     * Major Anions (Negative Charge):         * Chloride ($Cl^{-}$)         * Bicarbonate ($HCO_{3}^{-}$)         * Phosphate ($PO_{4}^{3-}$)

• Normal Serum Lab Values:     * Sodium ($Na^{+}$): $135-145\,mEq/L$     * Potassium ($K^{+}$): $3.5-5.0\,mEq/L$     * Calcium ($Ca^{2+}$): $9.0-10.5\,mg/dL$     * Magnesium ($Mg^{2+}$): $1.5-2.5\,mEq/L$

Sodium ($Na^{+}$) Imbalances

• Hyponatremia: Serum sodium content < 135\,mEq/L.     * Types: Hypovolemic and Hypervolemic.     * Signs/Symptoms: Confusion, lethargy, weakness, muscle cramping, seizures, anorexia, nausea, and vomiting. Serum osmolality will be < 290\,mOsm/kg.     * Nursing Interventions: Administer IV fluids containing Sodium; encourage high-sodium foods; monitor vital signs, I&O, and labs; administer hypertonic IV saline as ordered.     * Dietary Sources: Breads, cheeses, chips, processed meats (lunch meat, hot dogs, bacon, ham), commercially canned foods, and table salt.

• Hypernatremia: Serum sodium content > 145\,mEq/L.     * Signs/Symptoms: Thirst, dry sticky mucous membranes, weakness, elevated temperature, confusion, irritability, decreased LOC, hallucinations, and seizures. Serum osmolality will be > 290\,mOsm/kg.     * Nursing Interventions: Increase water intake, implement sodium-restricted diets, monitor vital signs and LOC, and administer hypotonic IV solutions as ordered.

Potassium ($K^{+}$) Imbalances

• Hypokalemia: Serum potassium content < 3.5\,mEq/L.     * Signs/Symptoms: Weak irregular pulse, fatigue, lethargy, anorexia, nausea, vomiting, muscle weakness/cramping, decreased peristalsis, hypoactive bowel sounds, paresthesia, and cardiac dysrhythmias.     * Nursing Interventions: Monitor heart rate/rhythm via cardiac monitor; monitor labs; administer Potassium supplements or IV fluids with Potassium. Warning: NEVER administer Potassium via IV Bolus or IV Push.     * Dietary Sources: Fish (not shellfish), whole grains, nuts, broccoli, cabbage, carrots, potatoes (with skins), bananas, cantaloupe, oranges, and nectarines.

• Hyperkalemia: Serum potassium content > 5.0\,mEq/L.     * Signs/Symptoms: Anxiety, irritability, confusion, muscle weakness, flaccid paralysis, paresthesia, GI hyperactivity (diarrhea, abdominal cramping), cardiac dysrhythmias, cardiac arrest, bradycardia, heart block, and irregular pulses.     * Nursing Interventions: Monitor heart rate/rhythm via cardiac monitor; limit Potassium-rich foods; administer Kayexalate, glucose, and insulin (to shift K back into cells), or prepare for dialysis as ordered.

Calcium ($Ca^{2+}$) Imbalances

• Hypocalcemia: Serum calcium content < 9.0\,mg/dL.     * Signs/Symptoms: Confusion, anxiety, hyperactive reflexes, cardiac dysrhythmias, muscle cramps progressing to tetany and seizures, numbness/tingling of extremities, and positive Trousseau’s and Chvostek’s signs.     * Nursing Interventions: Monitor heart rate/rhythm; implement fall and seizure precautions; administer Calcium and Vitamin D as ordered; encourage Calcium-rich foods.     * Dietary Sources: Dark green leafy vegetables, canned salmon, soy products, and milk.

• Hypercalcemia: Serum calcium content > 10.5\,mg/dL.     * Signs/Symptoms: Lethargy, stupor, coma, depressed deep muscle strength and tone, dysrhythmias, anorexia, nausea, vomiting, constipation, pathological fractures, and kidney stones.     * Nursing Interventions: Monitor heart rate/rhythm; encourage increased fluid intake; increase patient activity (including active ROM); restrict Calcium-rich foods.

Magnesium ($Mg^{2+}$) Imbalances

• Hypomagnesemia: Serum magnesium content < 1.5\,mEq/L.     * Signs/Symptoms: Neuromuscular irritability with tremors, disorientation, vertigo, confusion, increased reflexes, convulsions, positive Trousseau’s and Chvostek’s signs, tachycardia, elevated BP, respiratory difficulties, anorexia, and dysphagia.     * Nursing Interventions: Assess vital signs and mental status; monitor heart rhythm; administer Magnesium; assess swallowing before providing food/fluids; include Magnesium-rich foods; avoid alcohol; implement seizure precautions.     * Dietary Sources: Cereal grains, nuts, dried fruit, legumes, green leafy vegetables, dairy, meat, fish, and chocolate.

• Hypermagnesemia: Serum magnesium content > 2.5\,mEq/L.     * Signs/Symptoms: Warm flushed appearance, peripheral vasodilation, N/V, drowsiness, lethargy, generalized weakness, decreased deep tendon reflexes, hypotension, dysrhythmias (bradycardia, heart block), respiratory depression, and respiratory arrest.     * Nursing Interventions: Assess vital signs, LOC, and neuromuscular status; encourage increased oral and IV fluid intake; administer loop diuretics as ordered; provide respiratory support; low magnesium diet; dialysis.

Assessment of Fluid and Electrolyte Status

• Health History: Review recent changes in fluid intake, diet, and lifestyle habits.

• Vital Signs: Monitor for prolonged fever, tachycardia, respiratory changes, and blood pressure alterations.

• Intake and Output (I&O):     * Intake: Includes oral fluids and foods that liquefy at room temperature.     * Output: Measurable body fluids and drainage.     * 24-Hour Balance: Totals from each shift are added daily to monitor trends.

• Weight:     * A change of $1\,kg$ ($2.2\,lb$) is equivalent to $1\,L$ ($1000\,mL$) of fluid.

• Edema Grading (4+ Scale):     * 1+: Slight indentation ($2\,mm$); returns to normal quickly.     * 2+: Deeper indentation ($4\,mm$); lasts longer.     * 3+: Obvious indentation ($6\,mm$); lasts several seconds.     * 4+: Deep indentation ($8\,mm$); remains for several minutes.

• Skin and Mucous Membranes:     * Turgor: Pinched skin should return to normal quickly. "Tenting" indicates fluid volume deficit (less accurate in elderly).     * Mucous Membranes: Normal is pink/moist. Deficit results in dry, sticky membranes, tongue furrows, and cracked lips.

• Risk Factors/Susceptibility:     * Age: Infants and elderly are more susceptible.     * Stress: Leads to fluid retention and decreased renal excretion.     * Weight: Total body fluid is disproportionate in obese individuals.     * Surgery: NPO transitions, blood loss, drainage, and vomiting.     * Medical Conditions: Cardiac, hepatic, renal, and respiratory disorders.

Nursing Diagnosis and Planning

• Example Diagnoses:     * Fluid Imbalance: Supported by N/V, output > intake, dry membranes, urine specific gravity $1.041$, urine osmolarity $1080\,mOsm/kg$.     * Fluid Retention: Supported by pulse $116$ (bounding), respirations $32$ (labored), 3+ pitting edema, lung crackles, and weight gain.     * Dehydration: Supported by fluid loss, weak pulse, tachycardia, and thirst.

• Planning/Outcomes: Goals include moist mucous membranes by end of shift, zero pitting edema within 48 hours, and normal pulse rate by discharge.

Implementation: Fluid and Electrolyte Management

• Restricting Fluid Intake:     * Allocate $50\%$ of the total allowance during the day shift (highest activity/two meals).     * Divide the remainder between meals and medications.     * Subtract running IV fluids from the total restriction.

• Restricting Electrolyte Intake:     * Sodium restrictions classified as mild, moderate, or severe.

• Oral Replacement:     * Increase fluid intake to offset losses (at least $50\%$ during the day).     * Avoid caffeine.     * Common supplements: Potassium and Calcium. Potassium is often needed with potassium-wasting diuretics.

• Intravenous (IV) Therapy:     * IV fluids are viewed as medication; follow the rights of medication administration.     * Advantages: Immediate access, faster onset, predictable effect, nutrition access, and blood product transfusion.     * Types: Crystalloids (Isotonic, Hypotonic, Hypertonic) like Normal Saline or Lactated Ringers; Colloids (protein/starch) used for volume and oncotic pressure.

IV Site Assessment and Infiltration

• Infiltration Management: If suspected, stop infusion immediately, remove catheter, assess for extravasation, apply thermal applications, elevate extremity, and outline the area with a marker.

• Signs of Infiltration: Swelling, tenderness, coolness, firmness, and skin blanching.

• Infiltration Scale:     * Grade 0: No symptoms.     * Grade 1: Blanched skin, edema < 1\text{ inch}, cool to touch, possible pain.     * Grade 2: All Grade 1 symptoms plus edema of $1-6\text{ inches}$.     * Grade 3: All previous symptoms plus translucent extremity, edema > 6\text{ inches}, mild-moderate pain, possible numbness.     * Grade 4: All previous symptoms plus tight/leaking skin, deep pitting edema, circulatory impairment, moderate-severe pain (considered extravasation).

Questions & Discussion

• NGN NCLEX-RN Practice Question 1: The nurse is reviewing the laboratory results of a client who has been experiencing prolonged vomiting. The client's serum potassium level is $2.9\,mEq/L$. Select four of the following assessment findings that the nurse should anticipate:     * Correct Answers: Muscle weakness and cramping; Decreased peristalsis and hypoactive bowel sounds; Weak, irregular pulse; Cardiac dysrhythmias.

• Knowledge Check: The nurse is reviewing the fundamental principles of fluid and electrolyte balance. The nurse identifies that body fluids shift back and forth through cell and vessel walls. Which of the following terms best describes this movement of fluid?     * Correct Answer: Osmosis.

• NGN NCLEX-RN Practice Question 2: The nurse is caring for a client who has a serum sodium level of $152\,mEq/L$. The Nurse notes the client is experiencing thirst and dry, sticky mucous membranes. Select four nursing interventions that are appropriate for this client:     * Correct Answers: Administer hypotonic IV saline solutions as ordered; Monitor vital signs, level of consciousness, and laboratory results; Encourage the client to increase water intake; Implement a sodium-restricted diet.