Fluids and Electrolytes - Body Fluid Management

**Fluids and Electrolytes** covers critical concepts about body fluid composition, movement, and regulation, which are essential in understanding fluid imbalances and their management. **Key Concepts of Fluids and Electrolytes** 1. **Body Water Distribution**: - **50-60% of body weight is...

**Fluids and Electrolytes** covers critical concepts about body fluid composition, movement, and regulation, which are essential in understanding fluid imbalances and their management. **Key Concepts of Fluids and Electrolytes** 1. **Body Water Distribution**: - **50-60% of body weight is water**. This is divided into: - **Intracellular Fluid (ICF)**: Inside the cells (40% of body weight). - **Extracellular Fluid (ECF)**: Outside the cells (20%), including: - Interstitial fluid (15%) (outside cell) - Intravascular fluid (blood plasma, 5%) (within cell) - **Transcellular Fluid:** Includes CSF, pleural, peritoneal, and synovial fluids. - The amount of water varies by age and sex; infants have a higher percentage, and body water decreases with age. - - - 2. **Fluid Intake and Output**: - **Average daily fluid intake**: 2500 ml/day (ranges between 1500-3000 ml/day). - Fluids come from liquids, food, and medical sources (e.g., IV fluids). - **Fluid loss** occurs via urination, bowel movements, perspiration, and breathing. #### Composition of Body Fluids - **Components**: Body fluids consist of solutes, solvents, electrolytes, and proteins. 3. **Functions of Body Fluids**: - Transport nutrients and waste. - Maintain body temperature and act as a shock absorber. - Serve as a medium for metabolic reactions. **Tonicity of Body Fluids:** - **Isotonic Fluids:** Have a concentration of solutes comparable to 0.9% NaCl, maintaining equilibrium without causing fluid shifts. - Examples: Normal saline (0.9% NaCl). - Volume replacement in hypovolemia, dehydration, and shock. - Maintenance fluids during surgery and for patients unable to take fluids orally. - **Hypertonic Fluids:** Have a higher concentration of solutes compared to plasma, drawing water out of cells. - Examples: 3% NaCl. **Uses:** - Severe hyponatremia, cerebral edema, severe hypoglycemia. - Acute care requiring rapid fluid and solute correction. - **Hypotonic Fluids:** Have a lower concentration of solutes compared to plasma, causing water to move into cells. - Examples: 0.45% NaCl, 0.33% NaCl solutions. **Uses:** - Cellular dehydration in diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS). - Hypernatremia and as maintenance fluids for patients at risk of hypernatremia or hyperchloremia. - **D5 Water**: Isotonic solution outside the body but becomes hypotonic once administered. **Movement of Fluids** 1. **Osmosis**: - Movement of water across a membrane from a low solute concentration to a higher concentration. - Example: Water moving into cells to balance solute levels. 2. **Diffusion**: - Movement of particles (solutes) from a high to a low concentration. - Factors: Size, Concentration, Temperature - Example: Oxygen moving from the lungs into the bloodstream. 3. **Filtration**: - Movement of water and solutes from an area of high pressure to low pressure. - **Hydrostatic pressure** helps push fluids in this process. 4. **Facilitated diffusion**: is a passive transport process that allows larger or polar molecules to cross cell membranes with the help of transport proteins (carrier proteins or channels). 5. **Active Transport**: - Uses energy (ATP) to move solutes from a low concentration to a high concentration. - Example: Sodium-potassium pump in cells. 6. **Translocation:** Continuous movement of fluids and chemicals between compartments to maintain balance. - Example, electrolytes like sodium and potassium move between cells and extracellular fluid to regulate nerve impulses and muscle function. FUN FACT: **180 L** of fluid from the blood is being filtered by the kidney each day! #### **Electrolytes (Ions: Cations & Anions)** - **Sources**: Food intake, ingested fluids, medications, IV fluids, TPN solutions. - **Dynamics**: Distribution, excretion, and regulation. - Average dietary intake of sodium is about 6-14 g/day - 1 tsp of table salt = 2000 mg - 1 tsp soy sauce = 1029 mg 1. **Sodium (Na+)**: - Major ECF cation. (Regulated by kidney) - Controls fluid volume and **nerve transmission**. - Normal range: **135-145 mEq/L**. (Milliequivalents per Liter) 2. **Potassium (K+)**: - Major ICF cation. - Regulates muscle contraction and protein synthesis. - Normal range: **3.5-5.0 mEq/L**. (Milliequivalents per Liter) 3. **Calcium (Ca++)**: - Involved in bone health, muscle function, and blood clotting. - Normal range: **9-10.5 mg/dL**. (Milligrams per Deciliter) 1. Ionized calcium: Pure calcium ions. (free) 2. Bound calcium: Calcium bonded with other components. (CHON) 4. **Phosphorus (Major ICF Anion)**: - 80% found in bones, often bound with calcium. - Regulated by PTH - Normal range: **3-4.5 mg/dL.** 5. **Magnesium (Mg++)**: - Affects muscle contraction, ATP production, and protein synthesis. - 60% stored in bones and cartilage - Normal range: **1.3-2.1 mg/dL**. 6. **Chloride (Major ECF Anion)**: - Important for forming hydrochloric acid in the stomach. - Normal range: **98-106 MEQ/L (mmol/L)** **Fluid and Electrolyte Imbalances** **Fluid** 1. **Hypovolemia (Fluid Volume Deficit)**: - Causes: Hemorrhage, vomiting, diarrhea, excessive urination. - Symptoms: Thirst, weight loss, low blood pressure, and dry skin. (Hemoconcentration) - Management: Increase fluid intake, treat the underlying cause, administer IV fluids. - **ORS -- Oral Rehydration Solution (1L water, 2 tbsp sugar, ¼ tsp salt, ¼ tsp baking soda)** 2. **Hypervolemia (Fluid Volume Excess)**: - Causes: Excessive fluid intake, heart failure, kidney disease. - Symptoms: Weight gain, high blood pressure, pitting edema, and fluid in the lungs. (Hemodilution) - Management: Fluid restriction, diuretics, manage the underlying cause. - 3. **Third Spacing**: - Fluid shifts from the blood into body tissues, leading to edema. (Anascara) - Common in severe burns or allergic reactions. - Management: Restore osmotic pressure with colloids (e.g., albumin) and use diuretics. **Electrolytes** **Sodium (Na+) Imbalances** **1. Hyponatremia (Low Sodium)** - **Causes**: - Excessive sweating or urination. - Overconsumption of plain water (without electrolytes). - Prolonged vomiting or diarrhea. - Conditions like Addison's disease (adrenal insufficiency). - **Symptoms**: - **Mental confusion** and personality changes. - **Muscle weakness** and restlessness. - Severe cases can lead to **convulsions and coma**. - **Management**: - Mild cases: Increase sodium intake via food or oral supplements. - Severe cases: IV sodium solutions to restore balance. **2. Hypernatremia (High Sodium)** - **Causes**: - Excessive salt intake without enough water. - Profuse diarrhea, decreased water intake (e.g., in elderly). - Excessive water loss due to sweating. - **Symptoms**: - **Thirst**, dry mucous membranes, decreased urine output. - Severe cases can result in **lethargy or coma**. - **Management**: - Drink plain water or use IV hypotonic solutions to reduce sodium concentration. **Potassium \[Muscle Contraction\] (K+) Imbalances** **1. Hypokalemia (Low Potassium)** - **Causes**: - Diuretic use (medications that cause the body to lose water and potassium). - Severe vomiting, diarrhea, and prolonged suctioning (e.g., from a nasogastric tube). - Large doses of corticosteroids and insulin administration. - **Symptoms**: - **Fatigue**, weakness, muscle cramps, and cardiac arrhythmias. - Severe hypokalemia can cause **paralysis** and **death** due to cardiac or respiratory failure. - **Management**: - Mild cases: Increase potassium intake through diet (bananas, oranges, leafy greens). - Severe cases: IV potassium chloride (KCl) should be administered slowly to avoid complications. **2. Hyperkalemia (High Potassium)** - **Causes**: - Kidney failure (inability to excrete potassium). - Overuse of potassium supplements or potassium-sparing diuretics. - Crushing injuries (release of potassium from damaged cells). - **Symptoms**: - **Muscle weakness**, paresthesia (tingling), and **cardiac dysrhythmias**. - Severe cases can result in **life-threatening heart conditions** like wide QRS complexes or absent P waves on ECG. - **Management**: - Stop potassium intake. - Use **insulin with glucose** or **cation-exchange resins** (e.g., Kayexalate) to lower potassium levels. - Dialysis in severe cases to remove excess potassium. **Calcium (Ca++) Imbalances** **1. Hypocalcemia (Low Calcium)** - **Causes**: - Vitamin D deficiency (important for calcium absorption). - Hypoparathyroidism (underactive parathyroid glands). - Pancreatitis or multiple blood transfusions (due to additives in the blood that lower calcium levels). - **Symptoms**: - **Tingling** around the mouth, muscle cramps, positive **Trousseau's sign** (wrist spasm), and **Chvostek's sign** (facial muscle spasm). - Severe cases may cause **tetany** (severe muscle spasms), seizures, and cardiac dysrhythmias. - **Management**: - Oral calcium and Vitamin D supplements for mild cases. - IV calcium gluconate for severe cases. **2. Hypercalcemia (High Calcium)** - **Causes**: - Parathyroid gland tumors or excessive intake of Vitamin D. - Prolonged immobilization (leading to calcium release from bones). - Certain cancers (e.g., multiple myeloma). - **Symptoms**: - **Deep bone pain**, constipation, **mental changes** (memory loss), and kidney stones. - Severe cases can lead to **pathological fractures**. - **Management**: - Increase fluid intake and limit calcium-rich foods. - IV fluids (e.g., NaCl solutions), diuretics (e.g., Lasix), and medications like **calcitonin** or **corticosteroids** for severe cases. **Magnesium (Mg++) Imbalances** **1. Hypomagnesemia (Low Magnesium)** - **Causes**: - Chronic alcoholism, severe malnutrition, or prolonged use of diuretics. - Intestinal malabsorption syndromes or renal disease. - **Symptoms**: - **Tachycardia**, neuromuscular irritability (tremors, cramps), and **seizures**. - Positive **Chvostek's and Trousseau's signs**. - **Management**: - Mild cases: Oral magnesium supplements or magnesium-rich foods. - Severe cases: IV magnesium sulfate, but BP should be closely monitored as magnesium can cause **vasodilation**. **2. Hypermagnesemia (High Magnesium)** - **Causes**: - Renal failure or excessive use of antacids/laxatives containing magnesium. - **Symptoms**: - **Flushing**, lethargy, muscle weakness, and **low blood pressure**. - Severe cases can cause **coma** or respiratory failure. - **Management**: - Stop magnesium intake. - Administer **calcium gluconate** (the antidote to magnesium) and monitor vital signs. **Phosphorus (HPO4) Imbalances** **1. Hypophosphatemia (Low Phosphate)** - **Causes**: - Hyperparathyroidism (too much PTH), malnutrition, or conditions like diabetic ketoacidosis. - Chronic alcohol abuse or overuse of diuretics. - **Symptoms**: - **Muscle weakness**, tingling, tremors, and confusion. - Severe cases can lead to **bone weakness** and respiratory failure. - **Management**: - Mild cases: Oral phosphate supplements or phosphate-rich foods (milk, meats). - Severe cases: IV phosphate replacement. **2. Hyperphosphatemia (High Phosphate)** - **Causes**: - Kidney failure or hypoparathyroidism (reduced PTH). - Overuse of laxatives or phosphate-containing enemas. - **Symptoms**: - Often **asymptomatic**, but can lead to **calcium-phosphate crystal formation**, resulting in tissue damage. - Associated with **hypocalcemia**, which causes numbness, tingling, and muscle cramps. - **Management**: - Restrict phosphate-rich foods, use calcium-based antacids to bind phosphate, or dialysis for severe cases **Regulation Mechanisms** 1. **Osmoreceptors**: - Located in the hypothalamus, they regulate fluid intake (thirst) and output (urine) based on fluid concentration in the blood. - Triggered by 3 factors: - Decreased BV by 10% - Systolic BP falls below mmHG - RA is underfilled 2. **Renin-Angiotensin-Aldosterone System (RAAS)**: - Regulates blood pressure and fluid balance by adjusting sodium and water levels in the body. **Components**: - Kidney secretes renin. - Liver secretes angiotensin. - Lungs secrete ACE. - Adrenal gland secretes aldosterone. **Mechanism:** - **Renin Release:** When the body detects any of the above triggers, the kidneys release the enzyme renin into the bloodstream. - **Angiotensinogen Conversion:** Renin converts angiotensinogen (a protein released by the liver) into angiotensin I. - **Angiotensin I to Angiotensin II:** Angiotensin I is converted to angiotensin II by the enzyme angiotensin-converting enzyme (ACE), primarily in the lungs. **Effects of Angiotensin II:** - **Vasoconstriction:** Angiotensin II causes blood vessels to constrict, increasing blood pressure. - **Aldosterone Secretion:** Angiotensin II stimulates the adrenal glands to release aldosterone. - **ADH Release:** Angiotensin II also prompts the release of antidiuretic hormone (ADH) from the pituitary gland. 3. **Atrial Natriuretic Peptide (ANP)**: - Released when the heart is overstretched, promoting the excretion of sodium and water, reducing fluid volume. **Nursing Care Tips:** - Monitor fluid intake and output regularly. - Recognize early signs of fluid imbalances, such as changes in weight or urine output. - Teach patients to respond to thirst and avoid dehydration, especially in hot weather.