learning Objectives - Demonstrate skill in management of client with fluid and electrolyte imbalance.
Hours - 4
Teaching and Learning Activities - Lecture cum discussion Demonstration
Assessment Methods - Short answer Objective type Essay type Return demonstration
Content of the chapter
a) Water contents of body, electrolyte and Acid
– Base balance
b) Homeostasis
c) Review mechanism of regulating fluid and
electrolyte movement
d) Fluid and electrolyte Acid-Base imbalance
and its management
Fluid and Electrolyte Balance and Imbalance
a) Water Contents of the Body, Electrolyte and Acid–Base Balance
Water Content of the Body
- Total body water constitutes about 60% of body weight in adults
- Infants: ~70–75%
- Elderly: ~50–55%
- Distribution of body fluids
- Intracellular fluid (ICF): ~40% of body weight (inside cells)
- Extracellular fluid (ECF): ~20% of body weight
- Interstitial fluid
- Intravascular fluid (plasma)
- Transcellular fluid (CSF, synovial, pleural, etc.)
Electrolytes
Electrolytes are substances that dissociate into ions in solution and carry electrical charges.
- Major electrolytes
- Sodium (Na⁺): Main ECF cation; regulates water balance and nerve impulses
- Potassium (K⁺): Main ICF cation; vital for muscle and cardiac function
- Calcium (Ca²⁺): Bone formation, muscle contraction, blood clotting
- Magnesium (Mg²⁺): Enzyme activity, neuromuscular function
- Chloride (Cl⁻): Maintains osmotic pressure and acid–base balance
- Bicarbonate (HCO₃⁻): Major buffer in acid–base balance
- Phosphate (PO₄³⁻): Bone formation and cellular metabolism
Acid–Base Balance
- Normal blood pH: 7.35–7.45
- Maintained by:
- Buffer systems (bicarbonate, phosphate, proteins)
- Lungs (regulate CO₂)
- Kidneys (excrete or conserve hydrogen and bicarbonate ions)
b) Homeostasis
Homeostasis is the maintenance of a stable internal environment despite external changes.
- Regulates:
- Fluid volume
- Electrolyte concentration
- Osmolality
- Acid–base balance
- Achieved through:
- Nervous system
- Endocrine system
- Renal function
- Key hormones involved:
- Antidiuretic hormone (ADH)
- Aldosterone
- Renin–angiotensin–aldosterone system (RAAS)
- Atrial natriuretic peptide (ANP)
c) Mechanism of Regulating Fluid and Electrolyte Movement
Fluid Movement Mechanisms
- Diffusion
- Movement from high to low concentration
- Osmosis
- Movement of water across a semi-permeable membrane
- Filtration
- Movement due to hydrostatic pressure (e.g., in capillaries)
- Active Transport
- Movement against concentration gradient using energy (ATP)
Electrolyte Regulation
- Kidneys: Primary regulators (excretion and reabsorption)
- Lungs: Control CO₂ (acid component)
- GI tract: Absorption and loss of fluids and electrolytes
- Skin: Fluid loss through perspiration
d) Fluid and Electrolyte Acid–Base Imbalance and Its Management
Fluid Imbalance
1. Fluid Volume Deficit (Dehydration)
- Causes: Vomiting, diarrhea, burns, excessive sweating
- Signs & Symptoms:
- Thirst, dry mucous membranes
- Decreased urine output
- Hypotension, tachycardia
- Management:
- Oral rehydration therapy
- IV fluids (normal saline, Ringer’s lactate)
- Monitor intake and output
2. Fluid Volume Excess (Overhydration)
- Causes: Renal failure, heart failure, excessive IV fluids
- Signs & Symptoms:
- Edema, weight gain
- Hypertension
- Dyspnea
- Management:
- Fluid restriction
- Diuretics
- Sodium restriction
Electrolyte Imbalance (Examples)
- Hyponatremia: Confusion, seizures → Treat with sodium replacement
- Hypernatremia: Thirst, dry skin → Treat with hypotonic fluids
- Hypokalemia: Muscle weakness, arrhythmias → Potassium supplementation
- Hyperkalemia: Cardiac arrhythmias → Calcium gluconate, insulin with glucose
Acid–Base Imbalance
| Disorder | Cause | Management |
|---|---|---|
| Metabolic Acidosis | Renal failure, diarrhea | Treat cause, bicarbonate |
| Metabolic Alkalosis | Vomiting, excess antacids | Correct electrolytes |
| Respiratory Acidosis | COPD, hypoventilation | Improve ventilation |
| Respiratory Alkalosis | Anxiety, hyperventilation | Treat cause, rebreathe CO₂ |
Conclusion
Fluid, electrolyte, and acid–base balance are essential for normal cellular and organ function. Homeostasis is maintained through coordinated actions of the kidneys, lungs, hormones, and buffer systems. Early identification and proper management of imbalances prevent serious complications.