F & E

FLUID & ELECTROLYTES / ACID BASE BALANCE

NURS 196

LEARNING OBJECTIVES

• Describe the role of the kidneys, lungs, and endocrine glands in regulating the body’s fluid composition and volume.

• Describe the etiology, laboratory diagnostic findings, clinical manifestations, nursing and collaborative management of the fluid/electrolyte imbalance and acid/base imbalance.

• Describe the composition and indications of common intravenous fluid solutions.

• Discuss evidence-based practice implications necessary to prevent complications related to fluid and electrolyte imbalance.

HOMEOSTASIS

• Proper functioning of all body systems is essential to maintain fluid and electrolyte balance.

• Control of homeostasis involves various physiological systems.

AMOUNT AND COMPOSITION OF BODY FLUIDS

• Solvent: Liquids that hold a substance in solution, which is predominantly water.

• Solutes: Substances that are dissolved in a solution, which include electrolytes (charged particles) and nonelectrolytes (uncharged).

BODY FLUID COMPARTMENTS

• Extracellular Fluid (ECF): Fluid outside cells, includes:

  • Plasma: The liquid part of blood.

  • Interstitial Fluid: Fluid between cells.

• Intracellular Fluid (ICF): Fluid inside cells.

ELECTROLYTES

• Ions: Charged particles.

  • Cations: Ions with a positive charge.

  • Anions: Ions with a negative charge.

• Homeostasis: The mechanism where total cations equal total anions.

REGULATION OF BODY FLUID COMPARTMENT

• Osmosis: Movement of water from an area of low solute concentration to a high solute concentration.

• Diffusion: Movement of solutes from an area of high concentration to low concentration.

• Filtration: Movement of fluid from an area of high hydraulic pressure to an area of low hydraulic pressure.

• Active Transport: Movement of substances against their concentration gradient, requiring energy.

FILTRATION PRESSURE

• Hydrostatic Pressure: The pressure within the blood vessels that pushes fluid out.

• Colloid Osmotic Pressure: Pressure exerted by proteins in plasma that pulls fluid back into the circulatory system.

FLUID BALANCE

• Closely linked to and affected by electrolyte concentrations.

• Fluid Intake: The amount of liquids consumed.

• Fluid Loss: Includes various outputs:

  • Minimum urine output needed to excrete toxic waste products is 400 to 600 mL/day.

  • Insensible water loss occurs through skin, lungs, and stool.

HORMONAL REGULATION OF FLUID BALANCE

• Aldosterone: Hormone that helps regulate sodium and potassium levels.

• Antidiuretic Hormone (ADH): Regulates water retention in kidneys.

• Natriuretic Peptides: Hormones that promote the excretion of sodium and water to decrease blood pressure.

RECAP CONCEPTS

• Main solvent in human body: Water.

• Factors that affect body water content: Age, sex, physical activity, and environmental factors.

• Body fluid compartments: Extracellular fluid (ECF) and intracellular fluid (ICF).

• Movement of fluid within the body is governed by:

  • Diffusion

  • Osmotic factors

  • Hormone regulation of fluid balance.

FLUID IMBALANCES

• Fluid Deficit:

  • Nursing Diagnosis: Fluid Volume Deficit.

  • Hypovolemia: Occurs when isotonic fluid is lost or dehydration occurs.

• Fluid Overload:

  • Nursing Diagnosis: Fluid Volume Excess, which can be peripheral or central.

DEHYDRATION

• Fluid Volume Deficit:

  • Isotonic Dehydration: Water and electrolytes are lost equally.

  • Causes: Poor intake, loss of body fluids, bleeding.

  • Most common type of dehydration with no shift in fluid; decreased circulating blood volume from ECF leading to decreased tissue perfusion.

  • Hypertonic Dehydration: Water loss is greater than electrolyte loss.

  • Causes: Excessive sweating, diarrhea, vomiting, hyperventilation.

  • Water moves from ICF to ECF to dilute increased osmolarity of plasma, leading to cell shrinkage.

  • Hypotonic Dehydration: Electrolyte loss is greater than water loss.

  • Causes: Malnutrition, excessive ingestion of hypotonic fluids (water).

  • Excess sodium (Na extsuperscript{+}) and potassium (K extsuperscript{+}) losses from ECF result in decreased osmolarity, leading water to shift into ICF and cause cell swelling.

IV FLUIDS IN DEHYDRATION

• Isotonic Dehydration: Use isotonic IV fluids to add to circulating volume.

  • Examples: 0.9% NS, D5W, Ringer's Lactate.

• Hypertonic Dehydration: Use hypotonic IV fluids to hydrate cells, allowing water to move into the cells.

  • Examples: 0.45% NS, 0.33% Saline.

• Hypotonic Dehydration: Use hypertonic IV fluids to draw water out of cells back into capillaries, helping to increase plasma volume.

  • Examples: D5NS, may need electrolyte replacement with potassium chloride (KCl), 3% Sodium (Na extsuperscript{+}).

OVERHYDRATION

• Fluid Overload:

  • Clinical sign of another problem; fluid intake or retention exceeds the body's needs.

• Isotonic Hypervolemia: Excessive ECF with no shift, leading to circulatory overload and edema.

  • Causes: Renal failure, heart failure, excessive IV therapy, steroid use.

• Hypertonic Overhydration: Rarely caused by excessive sodium intake leading to fluid moving from ICF to ECF; results in cell shrinkage.

• Hypotonic Overhydration: Water intoxication results in decreased osmolarity of ECF, causing fluid to move into ICF resulting in cell swelling.

  • Electrolyte imbalances arise from dilution (hemodilution).

  • Causes: Renal failure, CHF, SIADH syndrome, excessive IV fluid, polydipsia.

NURSING ASSESSMENT FLUID VOLUME CHANGES

• At Risk Patients:

  • NPO, those on IVs, post-operative patients, and those experiencing bleeding, vomiting, or diarrhea.

  • Age: Infants and older adults are at greater risk, particularly the elderly, who may show reduced thirst and decreased kidney function.

• Intake:

  • Track oral, IV, tube feedings, and retained irrigation accurately, including types of fluids based on osmolarity.

  • Examples: Gatorade vs Water, Pedialyte for infants.

• Output:

  • Track urine, liquid stool, wound drainage, emesis, excessive sputum, or perspiration.

  • Ideal urine output is 0.5 mL/kg/hour or at least 30 mL/hour.

  • Measure urine specific gravity, which should range between 1.010-1.030.

NURSING ASSESSMENT FLUID VOLUME CHANGES (CONT.)

• Document: Include times for assessments.

• WEIGHT: Most accurate measurement of fluid status.

  • 1 L of H extsubscript{2}O = 1 kg of weight = 2.2 lbs.

  • Weigh patients at the same time, using the same calibrated scale, and under the same conditions.

  • Factors to consider: clothing, bedding, and ensuring drainage bags are empty prior to weighing.

• Skin Assessment: Evaluate the appearance for dryness vs. weeping, and check for edema (pitting vs. non-pitting).

  • Measure and compare extremities, abdominal girth when necessary.

NURSING ASSESSMENT - SKIN

Assessments of Fluid Deficit

• Turgor & Fluid Mobility:

  • Assess on sternum, abdomen, forehead, or forearm; pinch skin and count seconds until it returns.

  • Abnormal response is considered greater than __ seconds.

• Skin / Mucous Membranes:

  • Check the tongue for furrows and dryness.

  • Look for wrinkled/dry skin.

• Hand Veins:

  • observe for flatness.

Assessments of Fluid Excess (Fluid Accumulation)

• Assess for 3rd spacing/interstitial fluid.

• Edema Assessment:

  • Graded from 1+ to 4+; note brawny edema and weeping conditions.

• Skin should feel cool, pale, and firm to the touch, particularly over tibia, fibula, and sacrum.

• Hand veins may be full and bulging.

NURSING ASSESSMENT VITAL SIGNS

Fluid Volume Deficit vs. Overload

NEUROLOGICAL ASSESSMENT

• Brain cells vulnerable to fluid volume changes.

• Changes in volume can result in a reduced level of consciousness.

• Involvement of Sodium (Na extsuperscript{+}) is crucial for electrical activity through the sodium pump.

• Fluid Excess and Fluid Deficit: Evaluation of level of consciousness (LOC) is essential; consider seizure potentials/risks.

OTHER NURSING MEASURES

• Careful monitoring of I&O, including tube feedings; ensure adequate hydration.

  • With NGT to suction, monitor closely.

• Monitor output, subtracting any irrigation used.

• Only irrigate with saline to avoid fluid complications.

  • Diarrhea considerations as fluid loss may compromise health.

• Careful monitoring of IV Fluid administration.

  • Use pumps and ensure that both intake and output are zero at the beginning of shifts for accurate calculations.

• Labs: Monitor for hemoconcentration through renal function tests such as BUN and creatinine; aim for eGFR > 60 mL/min (indicating normal renal function).

• Monitor urine specific gravity; a specific gravity > 1.030 indicates dehydration with increased osmolarity, presenting as dark amber urine.

CASE STUDY

• C.H: An elderly patient, 68 years old, admitted for the treatment of acute respiratory failure.

  • Initially intubated and placed on a respirator.

  • Following two weeks, a tracheostomy performed due to the continued need for ventilator support.

  • Clinical course complicated by cardiac failure, multiple pneumonia episodes, and psychosis.

  • Treatment: Broad-spectrum antibiotics led to persistent diarrhea.

ELECTROLYTE IMBALANCE

• Can occur in healthy individuals as a result of changes in fluid intake and output.

• May be life-threatening if severe and can occur in any clinical setting.

SODIUM (Na+)

• Serum Level: 135-145 MEQ/L (major extracellular cation).

• Major Functions of Sodium:

  • ECF volume/water balance.

  • Maintenance of acid-base balance.

  • Transmission of nerve impulses and active/passive transport of cell membranes.

• Sodium Deficiency: Leads to neurological changes.

• Sources: Dietary intake.

• Elimination: Primarily through urine, sweat, and feces; regulated by hormones and the kidneys.

HYPERNATREMIA

• Definition: Sodium levels > 145 MEQ/L.

• Causes:

  • Water loss or sodium gain.

  • Oral or IV sodium intake exceeds water intake.

  • Decreased sodium excretion related to renal failure or steroids.

  • Excessive water loss due to conditions like Diabetes Insipidus.

  • Elderly aging changes and comatose states increase risk.

• Manifestations:

  • Cardiac effects including increased heart rate and arrhythmias.

  • Symptoms include thirst, dry tongue, edema, confusion, twitching, and restlessness.

  • Weight changes due to fluid shifts.

• Treatment:

  • IV fluids (isotonic), diuretics, monitoring vital signs, weights, and I&O.

  • Dietary restrictions where applicable.

• Mneumonic: S = Skin Flush, A = Agitation, L = Low Grade Fever, T = Thirsty.

HYPONATREMIA

• Definition: Sodium levels < 135 MEQ/L.

• Causes:

  • Water gain or sodium loss.

  • Excretory loss via GI losses, NG suctioning, vomiting, diarrhea, or excessive diaphoresis.

  • Diuretics or renal diseases such as SIADH syndrome.

  • Psychiatric behavior leading to excessive intake (polydipsia) or congestive heart failure (CHF) status.

• Manifestations:

  • Neurological: irritability, confusion.

  • Cardiac: rapid, thready pulse, hypotension.

  • Water Excess: rapid weight gain, increased GI motility.

  • Late signs include muscle weakness, shallow respiratory rate, pulmonary edema, and decreased renal output.

• Important Note: Sodium and water are always interconnected in physiological balance.

TREATMENT OF HYPONATREMIA

• If associated with water excess (hypervolemia):

  • Implement fluid restriction, osmotic diuretics (e.g., Mannitol) to promote water excretion without sodium loss, and hypertonic saline (3% NaCl) administered via pump.

• If caused by sodium losses:

  • Slow loss management and treat any vomiting, diarrhea, or drains.

  • Consider oral or IV sodium repletion.

  • Monitor vital signs, I&O, weights, and electrolyte levels including serum sodium and osmolarity.

• Clinical Alert: Watch for LOC changes and risk for seizures when sodium levels are imbalanced.

POTASSIUM (K+)

• Serum Level: 3.5 - 5.0 MEQ/L (major intracellular cation).

• Regulated by the sodium-potassium pump with influence from insulin; K extsuperscript{+} moves from ECF to ICF upon insulin release; conversely, it moves from ICF to ECF in states of acidosis, trauma, or exercise.

• K extsuperscript{+} changes can cause altered excitability in muscles and neurons.

• Potassium is primarily removed through the kidneys.

HYPERKALEMIA

• Definition: Potassium levels > 5.0 MEQ/L.

• Causes:

  • Excessive potassium intake or rapid delivery.

  • Usage of K extsuperscript{+} salt substitutes.

  • Renal failure or uncontrolled diabetes.

  • Acidosis and massive cell destruction or transfusions of old blood.

• Manifestations:

  • Irregular pulses leading up to EKG changes and potential cardiac standstill/arrest.

  • Muscle twitches, cramps, generalized irritability, and GI motility increases such as cramping and diarrhea.

• Management:

  • Immediate action to eliminate excess potassium via oral and parenteral means.

  • Support with IV dextrose and insulin to facilitate movement of K extsuperscript{+} back into cells.

  • Cardiac monitoring, strict I&O tracking, improved potassium elimination through diuretics, dialysis, and considerations for Kayexalate enemas.

HYPOKALEMIA

• Definition: Potassium levels < 3.5 MEQ/L.

• Causes:

  • Shift from ECF to ICF (resulting in low serum level).

  • Abnormal losses (diuretics, NG tube losses, diarrhea, vomiting, and wound drainage).

  • Elevated aldosterone levels leading to increased diuresis and potassium loss, and incidents of metabolic alkalosis.

• Manifestations:

  • Weakness, irregular pulses, arrhythmias, and hypotensive episodes.

  • Respiratory insufficiency and diminished tactile sensations.

  • Muscle weakness affecting legs, bowel, and pulmonary function.

MANAGEMENT OF HYPOKALEMIA

• Administer potassium chloride (KCl) to prevent low K extsuperscript{+} levels and continuously monitor lab findings while using diuretics.

• Identify high potassium foods for patient education (e.g., bananas, oranges).

• Oral Route: Liquid form of potassium is preferred; do not crush tablets.

• IV Route: Validate urine output—should be 0.5 mL/kg/hour to ensure renal function.

  • Typically, the infusion rate for KCl is set at 10 mEq/hour, and should never be administered as an IV push.

  • Never exceed 20 mEq/hour in infusion rates and consistently monitor EKG telemetry during potassium infusion.

• Critical Care: Place emphasis on rest and careful monitoring protocols to prevent complications.

CALCIUM (Ca++)

• Serum Level: 9-10.5 mg/dL (major extracellular cation).

• Functions include:

  • Stabilizing excitable membranes, necessary for transmission of nerve impulses and cardiac contractions.

  • Acts as a cofactor in the blood-clotting cascade and is essential for muscle contractions.

  • Stabilizes bone structure and density.

• Requires vitamin D and parathyroid hormone (PTH) for regulation.

• Calcitonin: From thyroid gland helps decrease calcium levels in the serum.

• Important to note that small changes in calcium levels can have significant impacts on body functions.

HYPERCALCEMIA

• Definition: Calcium levels > 10.5 mg/dL.

• Causes:

  • Excessive oral intake or vitamin D.

  • Renal failure causing decreased excretion, immobility resulting in bone resorption, and hyperparathyroidism.

• Manifestations:

  • Muscle cramping, twitchiness followed by lethargy, increased risks for blood clots, tachycardia that may slow due to electrical conduction deficits.

  • Potential for fractures due to lowering of bone density.

• Management:

  • Fluid volume replacement with 0.9% NS, diuretics when necessary, and dietary restrictions with calcium avoidance.

  • Bone resorption inhibitors and cardiac monitoring are crucial.

HYPOCALCEMIA

• Definition: Calcium levels < 9 mg/dL.

• Causes:

  • Inadequate dietary intake, malabsorption syndromes, renal failure resulting in increased excretion, and thyroid surgical interventions damaging parathyroid glands.

• Manifestations:

  • Cardiac manifestations such as variable heart rate, lags in pulse and BP levels.

  • Positive Chovstek’s Sign (twitching upon facial nerve stimulation) and Trousseau’s Sign (carpal spasm upon blood pressure cuff inflation).

  • Signs of tetany with muscle spasms and potential respiratory failure.

• Management:

  • Dietary adjustments to increase calcium intake, oral supplements when necessary, and IV calcium administration for severe deficiencies.

CALCIUM & PHOSPHORUS

• Calcium (Ca++) and Phosphate (Pi) maintain an inverse relationship; a decrease in phosphorus causes an increase in calcium levels and vice versa.

• Signs and symptoms of hypocalcemia can mimic hyperphosphatemia.

• The balance of both minerals occurs at the kidney level, leading to potential imbalances in cases of renal failure.

PHOSPHORUS (Pi/Phosphate)

• Serum Level: 3-4.5 mg/dL (intracellular anion).

• Essential for energy metabolism (ATP formation), cell division, and metabolic processes.

• Plays a critical role in acid-base buffering and calcium homeostasis based on inverse relationship principles with calcium.

• Regulated by parathyroid hormone (PTH).

HYPERPHOSPHATEMIA

• Definition: Phosphate levels > 4.5 mg/dL.

• Causes: Typically results from renal failure or excessive intake of phosphate-containing laxatives/enemas which may lower calcium levels.

• Manifestations: Leads to increased neuromuscular excitability and potential skeletal muscle impact simulating hypocalcemia.

• Management: Treat similarly to hypocalcemia, with dietary restrictions on phosphates and ensuring high calcium intake; dialysis if required.

HYPOPHOSPHATEMIA

• Definition: Phosphate levels < 3 mg/dL.

• Causes: Chronic diarrhea, malabsorption syndromes, chronic alcoholism leading to increased calcium levels.

• Manifestations:

• Decreased ATP availability impacts normal metabolic functions and compromises oxygen release from hemoglobin, leading to increased muscle weakness and potential respiratory failure.

• Management: Focus on restoring normal phosphorus levels through dietary changes and supplementation, monitoring IV administration closely to avoid complications.

MAGNESIUM (Mg++)

• Serum Level: 1.8 - 2.6 mg/dL (intracellular cation).

• Known as the "stabilizer" at the cell membrane; excessive levels can affect cardiovascular and respiratory efforts.

• Critical for carbohydrate metabolism, ATP production, and processes requiring protein/DNA synthesis.

• Used in obstetrics to help manage intense uterine contractions.

HYPERMAGEMIA

• Definition: Magnesium levels > 2.6 mg/dL.

• Causes: Often linked to renal failure, uncontrolled diabetes, and excessive use of magnesium-containing antacids.

• Manifestations: Bradycardia, decreased respiratory effort, lethargy, and other neurological signs.

• Management: Monitor clinical parameters closely; levels > 10 can precipitate respiratory arrest; apply loop diuretics and dietary control over magnesium intake.

HYPOMAGNESEMIA

• Definition: Magnesium levels < 1.8 mg/dL.

• Causes: Related to intake deficiencies, excessive losses (e.g., prolonged diuretics, certain drug therapies).

• Manifestations: Mimics hypocalcemia with characteristics of hyperexcitability. Symptoms such as insomnia, muscle twitching, and paresthesias can occur.

• Management: Focus on restoring normal levels through dietary sources and IV supplementation under careful monitoring.

CHLORIDE (Cl−)

• Serum Level: 98-106 MEQ/L (major extracellular anion).

• Functions in conjunction with sodium to maintain osmotic pressure, necessary for hydrochloric acid production in the stomach.

• Exchanges with bicarbonate (HCO3−) to regulate bodily pH.

• Increased levels: May cause weakness, lethargy, altered respiratory patterns, and metabolic acidosis.

• Decreased levels: Associated with hyperexcitability, leading to shallow, rapid respiration and hypotension.

• Dietary sources include salt and foods rich in sodium.

CONSIDERATIONS FOR OLDER ADULTS

• Older adults face a higher risk for most electrolyte imbalances due to age-related changes in organ function.

• They have less total body water compared to younger adults which increases their susceptibility to fluid imbalances.

• Additionally, older adults are more likely to be on medications that affect fluid or electrolyte balance.