Fluid and Electrolyte Therapy Flashcards
What are the two main fluid compartments in the body?
Intracellular Fluid (ICF) and Extracellular Fluid (ECF).
How is Total Body Water (TBW) calculated in adults?
TBW = Body Weight (BW) x 0.6.
What is the difference between Intracellular Fluid (ICF) and Extracellular Fluid (ECF)?
ICF is fluid inside cells; ECF is fluid outside cells (e.g., plasma, interstitial fluid).
How much of the TBW is in the Intracellular Fluid (ICF)?
ICF accounts for about 28 litres or 40% of TBW.
How is fluid distributed between Intravenous Space (IVS) and Interstitial Space (ISS)?
IVS contains 3 liters (5% BW), ISS contains 11 liters (15% BW).
How does the percentage of water in the body differ at birth compared to adulthood?
At birth, TBW is 80% of BW with 45% in ECF; in adults, TBW is 60% of BW.
What are the typical daily fluid intake sources in a 70 kg adult?
Food: 750 mL, Drinks: 1500 mL, Metabolism: 250 mL (Total: 2500 mL).
What are the typical daily fluid losses in a 70 kg adult?
Sweat: 500 mL, Lungs: 400 mL, Urine: 1500 mL, Feces: 100 mL (Total: 2500 mL).
How does water move between the ECF and ICF?
Water moves by osmosis across semi-permeable membranes, based on osmotic gradients.
What forces control fluid movement between the IVS and ISS?
Fluid movement is driven by hydrostatic pressure and colloid osmotic pressure.
What are the major electrolytes found in the Intracellular Fluid (ICF)?
K+ (150 mEq/L), Mg2+ (30 mEq/L), PO4- (95 mEq/L).
What are the major electrolytes found in the Extracellular Fluid (ECF)?
Na+ (140 mEq/L), Cl- (110 mEq/L), HCO3- (30 mEq/L).
How is basal fluid maintenance calculated in adults and children?
Adults: 2.5 L/day or 30-35 mL/kg/day; Children: variable based on weight.
What are the daily requirements for sodium (Na+) and potassium (K+)?
Na+: 1-2 mmol/kg/day, K+: 1-2 mmol/kg/day.
How is fluid maintained parenterally in adults?
2 L D/W + 500 mL 0.9% saline + KCl, infused over 5 hours.
What causes pre-existing fluid deficits in patients?
Causes include fasting, decreased intake, vomiting, diarrhoea, fever, or sequestration.
What are ongoing fluid losses that need to be accounted for in perioperative management?
Ongoing losses include GIT losses, intra-op losses (e.g., blood loss, third space loss).
What is ‘third space loss’ in the context of fluid therapy?
Fluid shifts from ECF to a non-functional compartment, often due to trauma or surgery.
What factors should be considered preoperatively for fluid management?
History of fluid loss, urine output, signs of dehydration (e.g., dry mucous membranes).
What are the clinical signs of mild, moderate, and severe dehydration?
Mild: Thirsty, alert; Moderate: Lethargy, weak pulse; Severe: Comatose, hypotensive.
What laboratory investigations are relevant in assessing dehydration?
Elevated PCV, increased urea, sodium, high urinary specific gravity.
What fluids are used for resuscitation in cases of dehydration?
Crystalloids like Normal Saline (NS) and Ringer’s Lactate (RL); Dextrose in water (D/W) for pure water loss.
How is potassium (K+) deficit corrected in hypokalemia?
Correct with potassium infusion under ECG monitoring, not exceeding 20 mmol/hr.
What treatment is used for hyperkalemia in an emergency?
Calcium gluconate, sodium bicarbonate, glucose + insulin infusion, dialysis.
