Electrolyte Imbalances Quiz

Drugs for Fluid and Electrolyte Imbalances, and Acid-Base Disorders

• Drugs treat imbalances in fluid, electrolytes, and acid-base.
• Learning objectives include describing conditions requiring intravenous fluids, explaining sodium and potassium replacement therapies, discussing acidosis/alkalosis causes and treatments, and nurses' roles in pharmacologic management of these imbalances.
• A case study highlights Sandy, a 16-year-old, whose low sodium (136 mEq/L) and potassium (2.8 mEq/L) levels, potentially due to a fad diet and laxative use, necessitate assessment and management of electrolyte imbalances.

Body Fluid Compartments

• Water comprises ~60% of a middle-aged adult's body weight.
• Continuous fluid exchange occurs across semipermeable membranes, between intracellular and extracellular compartments.
• Large molecules and less ionized substances cross membranes with difficulty.

Major Fluid Compartments in the Body

• Intracellular fluid (25L): Within cells (40% of body weight)
• Interstitial fluid (12L): Surrounding cells.
• Plasma (3L): Fluid in blood vessels.

Control of Water Balance

• Water balance is critical for homeostasis.
• Imbalances of body fluids, electrolytes, and acid-base levels often necessitate intravenous (IV) therapy.

Osmolality

• Osmolality measures dissolved solutes per kilogram of fluid (~275-295 mOsm/kg).
• Common solutes include sodium, glucose, and urea.
• Changes in osmolality cause water movement; Sodium is the main contributor and is regulated by aldosterone.

Tonicity

• Tonicity describes a solution's ability to cause water movement across a membrane due to osmotic forces.
• Plasma tonicity is used as a reference point for IV solutions.

Osmosis

• Water moves from areas of low to high osmolality.
• Hypertonic IV fluid shifts water from interstitial space to plasma.
• Hypotonic IV fluid shifts water from plasma to interstitial space.
• Isotonic fluids cause no significant fluid shift.

Movement of Fluids and Solution Tonicity

• Isotonic: Equal osmolality; no net fluid movement.
• Hypertonic: Higher osmolality; draws water out of cells.
• Hypotonic: Lower osmolality; draws water into cells.

Regulation of Fluid Intake & Output

• Fluid intake/output is controlled by complex mechanisms.
• Thirst primarily regulates fluid intake.
• Kidneys, the renin-angiotensin-aldosterone system, and antidiuretic hormone (ADH) regulate fluid output.

Fluid Balance Disorders

• Deficient fluid balance (dehydration/shock) necessitates oral/intravenous fluid therapy.
• Excess fluid balance (fluid overload) requires diuretics.
• Identifying and addressing the underlying cause is paramount in fluid and electrolyte management.

Fluid Replacement Agents

• Fluid replacement corrects net fluid loss in the body (dehydration/shock).
• Intravenous fluid therapy maintains blood volume and blood pressure.

Intravenous Fluid Therapy

• IV fluids replace lost fluids/electrolytes (vomiting, diarrhea, laxatives, extensive sweating, burns, hemorrhage, uncontrolled ketoacidosis).
• Crystalloids and colloids are used in IV therapy.

Crystalloids

• Crystalloid IV solutions contain electrolytes.
• These mimic extracellular fluid (ECF) and help replace depleted fluids and promote urine output.
• Tonicity dictates the compartment the fluid enters.

Selected Crystalloid IV Solutions

• Crystalloid solutions vary in tonicity.
• Normal saline (0.9% NaCl) is isotonic; lactated Ringer's and Plasma-Lyte 148 solutions are also isotonic.
• Hypotonic solutions (like 0.45% saline) have lower and hypertonic solutions (like dextrose in water or normal saline) have higher osmolality than plasma.

Isotonic Crystalloids

• Isotonic crystalloids expand plasma volume without significant fluid shifts between compartments.
• These are primary choices in cases of fluid loss or low blood pressure. Normal saline is the most common choice.

Hypertonic Crystalloids

• Hypertonic crystalloids draw water from cells/tissues into vascular compartment.
• Indications include treating cellular edema, specifically cerebral edema.

Hypotonic Crystalloids

• Hypotonic solutions shift water from plasma to cells and tissues.
• Not for expanding plasma volume; use in situations of hypernatremia and cellular dehydration.

Adverse effects of Crystalloids

• Isotonic/hypertonic solutions may cause fluid overload.
• Hypotonic solutions might cause intravascular volume depletion and can cause hypotension/cellular swelling. This can lead to peripheral edema.

Colloids

• Colloids contain large molecules (proteins, starches) that mainly exert their effect in the intravascular space.
• They expand plasma volume more quickly due to osmotic pressure, drawing water from interstitial and intracellular spaces into the vascular compartment.
• Colloids are used to treat hypovolemia, shock, burns, or hemorrhage.

Selected Colloid Solutions (Plasma Volume Expanders)

• Various colloids, like albumin, dextrans, and hetastarch, are used as plasma volume expanders. They generally have isotonic tonicity.

Selected colloid solutions

• Normal serum albumin is the most frequent utilized colloid.
• Dextran is a synthetic polysaccharide, causing rapid plasma volume expansion.
• Hetastarch is a synthetic colloid similar to albumin, exerting effects over a longer period.

Adverse effects of Colloids

• Colloids, generally safe, can temporarily alter coagulation; blood-clotting factors should be monitored.
• Rare cases of anaphylaxis or kidney problems have occurred.

Blood Products

• Blood products are the only fluids that carry oxygen, supporting tissue oxygenation and increasing plasma volume.
• Human donors are required, making these fluids the most expensive.

Indications for Blood Products

• Cryoprecipitate/plasma protein factors are indicated for acute bleeding (>20% blood loss).
• Fresh frozen plasma (FFP) increases clotting factor levels in situations with demonstrated deficiencies.
• Packed red blood cells (PRBCs) increase oxygen-carrying capacity in cases of anemia or significant blood loss, up to 25% loss.
• Whole blood has the same uses as packed red blood cells, but is beneficial in severe cases of blood loss (more than 25% loss).

Adverse effects of Blood Products

• Blood products can induce incompatibility responses with the recipient's immune system.
• Crossmatching is critical to avoid transfusion reactions, anaphylaxis, and the transmission of pathogens (e.g., hepatitis, HIV).

Electrolyte Balance

• Positively or negatively charged inorganic molecules (electrolytes) are essential for nerve conduction, membrane permeability, water balance, and other bodily functions.

Electrolytes Important to Human Physiology

• A table of common cation and anion electrolytes and their formulas is provided for reference.

Electrolyte Imbalance

• Electrolyte imbalances often signal underlying medical conditions.
• These imbalances may stem from renal problems, adverse drug reactions, etc.
• Correcting the imbalance and addressing the underlying cause are critical to treatment.

Electrolyte Imbalances

• A table of diverse electrolytes, their abnormal levels, and associated treatment methods.

Sodium

• Sodium (a major extracellular cation) is crucial for regulating osmolality, water balance, and blood pressure.

Renal Regulation of Sodium and Potassium Balance

• A diagram showing the roles of the kidneys and adrenal gland (through aldosterone) in regulating sodium and potassium balance.

Hypernatremia

• Hypernatremia involves serum sodium levels above 145 mEq/L.
• Causes range from renal diseases & high sodium intake, to excessive water loss through inadequate water intake, watery diarrhea, fevers, burns, and high levels of corticosteroids.

Hypernatremia (Contd.)

• High serum sodium concentration leads to increased plasma osmolality, drawing water from the interstitial spaces and cells into the intravascular space; this results in cellular dehydration.
• Symptoms include thirst, fatigue, weakness, muscle twitching, convulsions, altered mental status, and decreased consciousness.
• Treatment of mild cases involves reducing sodium intake. For acute hypernatremia in hypovolemic patients, IV hypotonic solutions like 5% dextrose or 0.45% NaCl are indicated. Hypervolemic patients may benefit from diuretics.

Hyponatremia

• Hyponatremia involves serum sodium levels below 135 mEq/L.
• Causes include significant sodium loss due to kidney disease, excessive gastrointestinal fluid loss (vomiting, diarrhea), or burns, and excessive sweating.
• Hyponatremia may also be caused by excessive dilution of plasma (due to disorders of the adrenal gland or ADH secretion, or infusion of hypotonic solutions).

Hyponatremia (Contd.)

• Early symptoms are nausea, vomiting, anorexia, and abdominal cramping.
• Later symptoms may include altered neurologic status: confusion, lethargy, seizures, coma, and muscle twitching.
• The rate of correcting hyponatremia must be monitored carefully; rapid correction can lead to potentially dangerous complications. Therapy depends on whether the patient is hypovolemic or hypervolemic.

Potassium Balance

• Potassium (a primary intracellular cation) plays a critical role in nerve and muscle function, and acid-base balance.
• Aldosterone regulates potassium secretion, influencing its balance with sodium reabsorption in the kidneys.

Hyperkalemia

• Hyperkalemia involves serum potassium levels exceeding 5 mEq/L.
• Causes encompass various renal diseases, high potassium intake (especially from drugs like potassium-sparing diuretics).

Hyperkalemia (Contd.)

• Symptoms include muscle twitching, fatigue, paresthesia, dyspnea, cramping, and diarrhea. More serious complications include cardiac dysrhythmias, and cardiac arrest.
• Treatment of mild cases involves restricting potassium-rich foods.
• For severe hyperkalemia, IV glucose with insulin, albuterol, and calcium gluconate can be administered to reduce the potassium levels.

Hypokalemia

• Hypokalemia is characterized by serum potassium levels below 3.5 mEq/L.
• Causes include excessive potassium loss due to diuretic use, strenuous activity, or severe vomiting/diarrhea.

Hypokalemia (Contd.)

• Symptoms include muscle weakness, muscle cramps, lethargy, anorexia, dysrhythmias, paralysis, and even cardiac arrest.

Hypokalemia (Contd.)

• Mild cases may be treated by increasing dietary potassium intake (e.g., dried fruits, nuts, bananas, and avocados) or/and oral potassium supplements.
• Severe cases may need intravenous potassium supplementation, but IV administration rates and dilution are critical parameters.

Acid-Base Disorders

• Acidosis (pH below 7.35) and alkalosis (pH above 7.45) are imbalances needing attention to symptoms and addressing the underlying causes.

Regulation of Acid-Base Balances

• Buffers (bicarbonate and phosphate) help maintain normal body pH by neutralizing strong acids and bases.
• Lungs eliminate CO2, and kidneys remove H⁺, crucial for acid-base homeostasis.

Acid-Base Imbalances

• A diagram demonstrates the balance between acids and bases, with acidosis occurring at pH below 7.35 and alkalosis above 7.45.

Causes of Alkalosis and Acidosis

• Comprehensive table detailing respiratory and metabolic causes of acidosis and alkalosis. Examples include hypoventilation, hyperventilation, diarrhea, kidney failure, and ingestion of excess sodium bicarbonate, as well as diuretic use.

Pharmacotherapy of Acidosis

• Acidosis symptoms, such as lethargy, confusion, and coma, stem from central nervous system depression.
• Kussmaul breathing (rapid, deep respirations) may indicate the body's compensatory effort for metabolic acidosis.
• Treatment for metabolic acidosis involves administering sodium bicarbonate to reverse the excessive acid effects.

Pharmacotherapy of Alkalosis

• Alkalosis, often with central nervous system stimulation (nervousness, hyperreflexia, seizures), may have slowed shallow respirations as a compensatory mechanism.
• Mild alkalosis may be addressed with sodium chloride and potassium chloride; severe cases require ammonium chloride.

Nursing Implications (Assessment)

• Assess baseline fluid/electrolyte balance, vital signs, skin, membranes, daily weights, and intake/output.
• Monitor ECG to measure potassium levels before potassium administration.
• Evaluate for contraindications to therapies.
• Assess transfusion history.
• Establish venous access.

Nursing Implications (Monitor)

• Monitor electrolytes (serum/urine) during treatment.
• Monitor infusions’ rate and the solution; identify/evaluate infiltration/complications.
• Observe for therapeutic response based on evaluation of lab values (RBC/WBC/H&H/electrolytes), fluid balance, activities, and adverse effects
• Monitor closely.

Nursing Implications (Fluid Replacement)

• Administer colloids slowly.
• Monitor for fluid overload/heart failure.
• Carefully follow transfusion procedures.
• Monitor patients cautiously for transfusion reactions.

Nursing implication (Sodium Replacement Therapy)

• Assess sodium and electrolyte balance.
• Be alert to hyponatremia/hypernatremia-related signs/symptoms.
• Monitor serum sodium levels, urine specific gravity, serum/urine osmolality.
• Teach patients about symptoms related to fluid overload and appropriate fluid/electrolyte replacement strategies.

Nursing Implications (Potassium Infusion)

• IV potassium administration should not exceed 10 mEq/hr for patients not on cardiac monitors; higher rates may be appropriate in critically ill patients using cardiac monitors.
• Potassium should never be delivered as a bolus or undiluted IV solution.

Nursing Implications (Oral Potassium)

• Dilute oral potassium supplements in water or juice.
• Monitor for gastrointestinal distress (nausea, vomiting, abdominal pain, or bleeding).

Nursing Implications (Acid-Base Agents)

• Monitor arterial blood gases as appropriate for acid-base imbalances.
• Use sodium bicarbonate cautiously in patients with cardiac or renal conditions; assess risks.
• Administer ammonium chloride slowly based on the patient's condition and to mitigate potential risks of ammonia toxicity.

Case Study (Refer to the Recorded Lecture for the Answers)

• Sandy, a 16-year-old, presents with possible electrolyte imbalance potentially caused by a "fad diet" and laxative use, prompting assessment of her sodium (136 mEq/L) and potassium (2.8 mEq/L) levels.

Key Terms

• A summary of key terms for fluid and electrolyte imbalances, including dehydration, shock, IV therapy, crystalloids, colloids, hypernatremia, hyponatremia, hyperkalemia, hypokalemia, acidosis, and alkalosis.

Review Question

• Students should answer three multiple-choice questions after the lesson.
• A QR code provides access to the review questions.

References

• Provides citations from two pharmacology textbooks.

Test your knowledge on electrolyte imbalances, focusing on conditions like hypernatremia, hyponatremia, and hyperkalemia. This quiz covers definitions, clinical features, and management strategies related to serum sodium levels and other electrolytes. Challenge yourself to understand these critical aspects of medical practice.