Fluid and Electrolyte Therapy

Question 1

What are the two main fluid compartments in the body?

Answer 1

Intracellular Fluid (ICF) and Extracellular Fluid (ECF).

Question 2

How is Total Body Water (TBW) calculated in adults?

Answer 2

TBW = Body Weight (BW) x 0.6.

Question 3

What is the difference between Intracellular Fluid (ICF) and Extracellular Fluid (ECF)?

Answer 3

ICF is fluid inside cells; ECF is fluid outside cells (e.g., plasma, interstitial fluid).

Question 4

How much of the TBW is in the Intracellular Fluid (ICF)?

Answer 4

ICF accounts for about 28 litres or 40% of TBW.

Question 5

How is fluid distributed between Intravenous Space (IVS) and Interstitial Space (ISS)?

Answer 5

IVS contains 3 liters (5% BW), ISS contains 11 liters (15% BW).

Question 6

How does the percentage of water in the body differ at birth compared to adulthood?

Answer 6

At birth, TBW is 80% of BW with 45% in ECF; in adults, TBW is 60% of BW.

Question 7

What are the typical daily fluid intake sources in a 70 kg adult?

Answer 7

Food: 750 mL, Drinks: 1500 mL, Metabolism: 250 mL (Total: 2500 mL).

Question 8

What are the typical daily fluid losses in a 70 kg adult?

Answer 8

Sweat: 500 mL, Lungs: 400 mL, Urine: 1500 mL, Feces: 100 mL (Total: 2500 mL).

Question 9

How does water move between the ECF and ICF?

Answer 9

Water moves by osmosis across semi-permeable membranes, based on osmotic gradients.

Question 10

What forces control fluid movement between the IVS and ISS?

Answer 10

Fluid movement is driven by hydrostatic pressure and colloid osmotic pressure.

Question 11

What are the major electrolytes found in the Intracellular Fluid (ICF)?

Answer 11

K+ (150 mEq/L), Mg2+ (30 mEq/L), PO4- (95 mEq/L).

Question 12

What are the major electrolytes found in the Extracellular Fluid (ECF)?

Answer 12

Na+ (140 mEq/L), Cl- (110 mEq/L), HCO3- (30 mEq/L).

Question 13

How is basal fluid maintenance calculated in adults and children?

Answer 13

Adults: 2.5 L/day or 30-35 mL/kg/day; Children: variable based on weight.

Question 14

What are the daily requirements for sodium (Na+) and potassium (K+)?

Answer 14

Na+: 1-2 mmol/kg/day, K+: 1-2 mmol/kg/day.

Question 15

How is fluid maintained parenterally in adults?

Answer 15

2 L D/W + 500 mL 0.9% saline + KCl, infused over 5 hours.

Question 16

What causes pre-existing fluid deficits in patients?

Answer 16

Causes include fasting, decreased intake, vomiting, diarrhoea, fever, or sequestration.

Question 17

What are ongoing fluid losses that need to be accounted for in perioperative management?

Answer 17

Ongoing losses include GIT losses, intra-op losses (e.g., blood loss, third space loss).

Question 18

What is ‘third space loss’ in the context of fluid therapy?

Answer 18

Fluid shifts from ECF to a non-functional compartment, often due to trauma or surgery.

Question 19

What factors should be considered preoperatively for fluid management?

Answer 19

History of fluid loss, urine output, signs of dehydration (e.g., dry mucous membranes).

Question 20

What are the clinical signs of mild, moderate, and severe dehydration?

Answer 20

Mild: Thirsty, alert; Moderate: Lethargy, weak pulse; Severe: Comatose, hypotensive.

Question 21

What laboratory investigations are relevant in assessing dehydration?

Answer 21

Elevated PCV, increased urea, sodium, high urinary specific gravity.

Question 22

What fluids are used for resuscitation in cases of dehydration?

Answer 22

Crystalloids like Normal Saline (NS) and Ringer’s Lactate (RL); Dextrose in water (D/W) for pure water loss.

Question 23

How is potassium (K+) deficit corrected in hypokalemia?

Answer 23

Correct with potassium infusion under ECG monitoring, not exceeding 20 mmol/hr.

Question 24

What treatment is used for hyperkalemia in an emergency?

Answer 24

Calcium gluconate, sodium bicarbonate, glucose + insulin infusion, dialysis.

Question 25

How is bicarbonate (HCO3-) deficit managed?

Answer 25

Bicarbonate is given based on base deficit, weight, and response to treatment.

Question 26

How should fluid loss be managed intraoperatively?

Answer 26

Consider maintenance needs, ongoing losses, blood loss, and third space loss.

Question 27

What is the transfusion trigger point (TTP) in clinical practice?

Answer 27

TTP is reached after EBL > 10-20% of Estimated Blood Volume (EBV).

Question 28

How do crystalloids and colloids differ in their clinical use?

Answer 28

Crystalloids are for general volume replacement; colloids are for plasma expansion.

Question 29

What are the commonly used intravenous fluids (IVFs) in clinical practice?

Answer 29

Saline, Ringer’s Lactate, 5% Dextrose, Haemaccel, Gelofusine, Hetastarch.

Question 30

Which fluids are ideal for expanding the Extracellular Fluid (ECF) and Intracellular Fluid (ICF)?

Answer 30

Saline and Hartmann’s solution for ECF; 5% dextrose for TBW (affecting both ECF and ICF).