Fluids and Electrolytes

• Average adult fluid intake ranges from 2200 to 2700 mL daily.
• Normal kidney urine output is about 30 mL per hour.
• Adult body weight is 50% to 60% water.
• Homeostasis balances body fluids.

Fluid Compartments

• The extracellular fluid compartment includes interstitial and intravascular fluids.

Passive Transport

• Diffusion moves carbon dioxide out of cells.
• Osmosis involves water molecule diffusion into and out of cells.
• Filtration in the kidney starts urine formation.

Electrolytes

• Sodium (Na+) is the most abundant electrolyte in extracellular fluid, maintaining blood volume and blood pressure.
• Retaining fluid can cause hyponatremia.
• Potassium (K) helps muscles contract, including the heart.
• Phosphorus (P) supports teeth and bone health and cell and tissue repair.
• Calcium (Ca) supports heart function, blood clotting, and tooth formation, and is found in cells, bones, and teeth.
• Magnesium (Mg) keeps muscles and nerves healthy and regulates energy.
• Chloride (Cl) maintains acid-base balance and fluid levels in cells.

Electrolyte Imbalances

• Hyponatremia is a sodium level below 135 mEq/L.
• Hypernatremia is a sodium level above 145 mEq/L.
• Hypokalemia is a potassium level below 3.5 mEq/L, causing abdominal cramps, nausea, vomiting, fatigue, headache, apathy, apprehension, irritability, postural hypotension, muscle weakness, twitching, and tremors.
• Hyperkalemia is a potassium level above 5.0 mEq/L.
• Hypophosphatemia is a phosphorus level below 2.5 mg/dL.
• Hyperphosphatemia is a phosphorus level above 4.5 mg/dL
• Hypocalcemia is a calcium level below 9 mg/dL.
• Hypercalcemia is a calcium level above 11 mg/dL.
• Hypomagnesemia is a magnesium level below 1.5 mg/dL.
• Hypermagnesemia is a magnesium level above 2.5 mg/dL.
• Hypochloremia is a chloride level below 95 mEq/L.
• Hyperchloremia is a chloride level above 105 mEq/L.

Osmosis in Action

• Osmosis draws water from the interstitial space into the intravascular space via oncotic pressure.

Acid-Base Balance

• Blood buffers are physiologic buffers, which maintain pH balance by neutralizing excess acids and bases.
• The bicarbonate/carbonic acid buffer system is the key regulator of pH in blood and interstitial fluid
• Normal pH range is 7.35 to 7.45.
• Acidosis is defined as pH < 7.35.
• Alkalosis is defined as pH > 7.45.
• Normal PaCO2 range is 35 to 45 mmHg.
• Normal HCO3 range is 22 to 26 mEq/L.
• Arterial Blood Gas (ABG) measures the acidity or alkalinity of arterial blood.

Acidosis and Alkalosis Types

• Metabolic acidosis is defined as a gain of hydrogen ions or loss of bicarbonate, causing pH to drop, and is caused by diabetic ketoacidosis, severe diarrhea, dehydration, or renal failure.
• Metabolic alkalosis is defined as too much bicarbonate or too little hydrogen, often from excess vomiting, electrolyte imbalances, or hyperaldosteronism.
• Respiratory acidosis is defined as retained carbon dioxide, leading to decreased pH.
• Respiratory alkalosis is defined as hyperventilation, where carbon dioxide leaves the body, increasing pH.

Dosage Calculation

• The formula for dosage calculation is d (desired dose) = order, h (dose on hand) = have, q = quantity.
• Conversions involve Kg → g → mg → mcg.

Special Tests and Procedures

• Tap on the cheek to test for hypocalcemia (Chvostek sign); facial muscles will contract.
• Autologous blood transfusion involves patients donating their own blood for future transfusions, if needed.

Transfusion Reactions

• Blood transfusion reactions are life-threatening emergencies
• Blood transfusion reactions include chills, fever, low back pain, itching, hypotension, nausea, vomiting, decreased urine output, chest pain, wheezing, and apnea.

Recommendations

• If your calcium level is 6.2, engage in weight-bearing exercises to prevent osteoporosis
• Drink 3000-4000 L/day of fluid.