ch 32 fluid ,electrolytes, and acid base

Physiological Factors Affecting Fluid, Blood, Electrolyte, and Acid-Base Homeostasis - Body Fluid Compartments:

• Intracellular Fluid (ICF): Inside cells, regulated by active transport.

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

  • Intravascular Fluid: In blood vessels, maintains blood pressure.

  • Interstitial Fluid: Surrounds cells, regulated by electrolyte transport.

Physiological Factors Affecting Fluid, Blood, Electrolyte, and Acid-Base Homeostasis - Osmolality & Osmolarity:

• Osmolality: Dissolved particles per kg of fluid (280-300 mOsm/kg).

• Osmolarity: Dissolved particles per L of fluid.

Physiological Factors Affecting Fluid, Blood, Electrolyte, and Acid-Base Homeostasis - Key Electrolytes:

• Sodium (Na+): ECF balance, nerve impulses.

• Potassium (K+): ICF balance, cardiac & muscle function.

• Calcium (Ca++): Bone health, clotting, muscle contraction.

• Magnesium (Mg++): Neuromuscular function, cardiac activity.

• Phosphorus (HPO4−, H2PO4−): Energy metabolism, nucleic acid synthesis.

Physiological Factors Affecting Fluid, Blood, Electrolyte, and Acid-Base Homeostasis - Acid-Base Balance:

Maintained by buffer systems, respiratory compensation (CO2 levels), and renal compensation (H+/HCO3- excretion).

Common Alterations in Fluid, Blood, Electrolyte, and Acid-Base Balance - Fluid Imbalances:

• Hypovolemia: Fluid loss from vomiting, diarrhea, hemorrhage.

  Hypervolemia: Excess fluid from heart/kidney failure, high sodium intake.

  Hyperosmolality: Dehydration (↑ solute concentration).

  Hyposmolality: Water intoxication (↓ solute concentration).

Common Alterations in Fluid, Blood, Electrolyte, and Acid-Base Balance - Acid-Base Imbalances:

• Respiratory Acidosis: CO2 retention (e.g., COPD).

• Respiratory Alkalosis: CO2 loss (e.g., hyperventilation).

• Metabolic Acidosis: Acid buildup (e.g., ketoacidosis).

• Metabolic Alkalosis: Acid loss (e.g., vomiting).

Assessment Parameters for Imbalances -History:

Recent illnesses (vomiting, diarrhea).

Diet, fluid intake/output changes.

Assessment Parameters for Imbalances - Physical Signs:

• Body Weight: Sudden loss or gain.

• Vital Signs: BP, HR, respiratory rate.

• Skin Turgor: Poor elasticity = dehydration.

• Mental Status: Confusion, lethargy.

Assessment Parameters for Imbalances - Lab Tests:

• Serum Electrolytes: Na+, K+, Ca++, Mg++, PO4−.

• Urine Osmolality & Specific Gravity: Measures kidney function.

• Arterial Blood Gases (ABGs): Determines acid-base status.

Signs & Symptoms of Electrolyte Imbalances:

• Sodium (Na+):
  Hyponatremia (<135 mEq/L): Confusion, seizures, weakness.

  Hypernatremia (>145 mEq/L): Thirst, dry mucosa, restlessness.

• Potassium (K+):
  Hypokalemia (<3.5 mEq/L): Weakness, arrhythmias.

  Hyperkalemia (>5.0 mEq/L): Cardiac arrest, muscle twitching.

• Calcium (Ca++):
  Hypocalcemia (<8.5 mg/dL): Tetany, Chvostek/Trousseau signs.

  Hypercalcemia (>10.5 mg/dL): Weakness, kidney stones.

• Magnesium (Mg++):
  Hypomagnesemia (<1.5 mEq/L): Tremors, cardiac arrhythmias.

  Hypermagnesemia (>2.5 mEq/L): Respiratory depression.

• Phosphorus (PO4−):
  Hypophosphatemia (<2.5 mg/dL): Weakness, confusion.

  Hyperphosphatemia (>4.5 mg/dL): Muscle cramps, tetany

Normal & Abnormal Lab Values : Sodium (Na+)

135-145 mEq/L

Normal & Abnormal Lab Values : Potassium (K+)

3.5-5.0 mEq/L

Normal & Abnormal Lab Values : Calcium (Ca++)

8.5-10.5 mg/dL

Normal & Abnormal Lab Values : Magnesium (Mg++)

1.5-2.5 mEq/L

Normal & Abnormal Lab Values : Phosphorus (PO4−)

2.5-4.5 mg/dL

Normal & Abnormal Lab Values : pH

7.35-7.45

Normal & Abnormal Lab Values : PaCO2

35-45 mmHg

Normal & Abnormal Lab Values : HCO3-

22-26 mEq/L

IV Solutions & Osmolarity :

• Isotonic (250-375 mOsm/L): No fluid shift, restores volume.

  • Examples: 0.9% NaCl (Normal Saline), Lactated Ringer’s.

• Hypotonic (<250 mOsm/L): Moves fluid into cells (rehydration).

  • Examples: 0.45% NaCl (Half Normal Saline).

• Hypertonic (>375 mOsm/L): Pulls fluid from cells (treats hyponatremia).

  • Examples: 3% NaCl, D5NS (Dextrose 5% in Normal Saline).

Nursing Diagnoses & Plan of Care - Nursing Diagnoses:

• Deficient Fluid Volume

• Excess Fluid Volume

• Risk for Electrolyte Imbalance

Nursing Diagnoses & Plan of Care - Plan of Care:

• Monitor: Vital signs, weight, lab values.

• Manage Fluids: IV therapy, oral hydration.

• Electrolyte Replacement: Diet modifications, supplements.

• Patient Education: Signs of imbalances, proper fluid intake.

Key Takeaways :

• Electrolyte balance is critical for nerve, muscle, and heart function.

• Fluid imbalances can cause dehydration (hypovolemia) or fluid overload (hypervolemia).

• Acid-base balance relies on buffering, respiration, and kidney function.

• IV fluids must match the patient’s needs (e.g., isotonic for blood loss, hypotonic for dehydration).

• Early recognition of imbalances prevents complications.