PE15.1-4 | Fluids and Electrolytes — Graded Quiz

Holliday-Segar for 25 kg: first 10 kg × 100 = 1000, next 10 kg × 50 = 500, remaining 5 kg × 20 = 100. Total = 1600 mL/day.

Holliday-Segar: 100 mL/kg/day for first 10 kg, 50 mL/kg/day for next 10 kg, 20 mL/kg/day for additional kg beyond 20 kg. For a 25 kg child: 1600 mL/day.

For 25 kg: (10 × 100) + (10 × 50) + (5 × 20) = 1000 + 500 + 100 = 1600 mL/day.

Multiple signs (sunken fontanelle, sunken eyes, decreased skin turgor) without inability to drink = 'some dehydration' (Plan B). Since the infant can drink, IV is not required. ORS 75 mL/kg over 4 hours in a facility.

IMNCI dehydration classification: no dehydration (none of the signs) → Plan A; some dehydration (≥2 of: restless/irritable, sunken eyes, thirsty/drinks eagerly, slow skin pinch) → Plan B (75 mL/kg ORS over 4 h in facility); severe (lethargic, sunken eyes, unable to drink, very slow skin pinch) → Plan C (IV).

Two or more IMNCI signs without inability to drink = 'some dehydration', Plan B. The infant's ability to drink differentiates some from severe dehydration. Plan C is reserved for severe dehydration (lethargic, unable to drink, very sunken eyes).

Symptomatic severe hyponatraemia (seizures) requires acute correction with 3% saline 2–3 mL/kg to raise Na by 4–6 mmol/L rapidly, stopping seizure activity. Thereafter, total correction in 24 h must not exceed 10–12 mmol/L to prevent ODS.

Symptomatic hyponatraemia (seizures/coma): 3% NaCl 2–3 mL/kg IV bolus raises Na by ~4–6 mmol/L — enough to stop seizures. After stabilisation, slow correction: total rise ≤10–12 mmol/L in 24 h to avoid ODS. SIADH vs hypovolaemic hyponatraemia have different subsequent management.

When hyponatraemia causes seizures, acute emergency treatment with 3% hypertonic saline is required to rapidly raise sodium by 4–6 mmol/L. Normal saline alone is too slow. The total 24-hour correction must still not exceed 10–12 mmol/L (ODS prevention).

The correct sequence: (1) Stop K-containing fluids immediately; (2) Calcium gluconate — cardiac membrane stabilisation; (3) Insulin+dextrose — shift K intracellularly; (4) Sodium bicarbonate — shift K intracellularly; (5) Dialysis if refractory. Calcium gluconate is the first drug given when ECG changes are present.

Hyperkalaemia with ECG changes: (1) stop K input; (2) calcium gluconate 10% 0.5 mL/kg IV — membrane stabilisation (acts within 1–3 min); (3) insulin 0.1 U/kg + 25% dextrose 2 mL/kg or 10% dextrose 5 mL/kg — transcellular shift; (4) NaHCO3 1–2 mEq/kg IV; (5) salbutamol nebulisation; (6) removal: furosemide, resonium, dialysis.

When ECG changes are present: FIRST stop all potassium-containing fluids, THEN stabilise the cardiac membrane with calcium gluconate, THEN shift potassium intracellularly (insulin+dextrose, bicarbonate), THEN remove potassium (exchange resin, dialysis). Never start with dialysis or Kayexalate when the membrane is electrically unstable.

Maintenance for 15 kg: (10×100) + (5×50) = 1250 mL/day. Deficit for 5% dehydration: 5% × 15 kg = 0.05 × 15,000 mL = 750 mL. Total = 1250 + 750 = 2000 mL/24 h.

Total fluid = maintenance + deficit + ongoing losses. Deficit (mL) = % dehydration × 10 mL/kg × weight (kg). For 5% dehydration in a 15 kg child: 5 × 10 × 15 = 750 mL. Add to Holliday-Segar maintenance (1250 mL) = 2000 mL total. Replace half the deficit in the first 8 hours.

5% dehydration means deficit = 5 mL/kg × 15 kg... actually 5% of body weight in mL = 50 mL/kg × 15 kg = 750 mL. Maintenance 15 kg = 1250 mL. Total = 2000 mL.

Maximum safe IV potassium infusion rate in children is 0.5 mmol/kg/hr. Higher rates cause cardiac arrhythmia. Potassium must NEVER be given as an IV bolus. Concentration in IV fluid should not exceed 40 mmol/L for peripheral lines.

IV potassium: NEVER give as a bolus. Maximum infusion rate 0.5 mmol/kg/hr under ECG monitoring. Peripheral concentration ≤40 mmol/L. For severe symptomatic hypokalaemia (K<2.5 + weakness/arrhythmia) consider 1 mmol/kg/hr only with continuous ECG monitoring.

The maximum safe IV K+ infusion rate is 0.5 mmol/kg/hr. It must never be given as a bolus injection. Higher rates (1–2 mmol/kg/hr) risk fatal cardiac arrhythmia. Peripheral lines should have a K concentration of ≤40 mmol/L.

Hypernatraemic dehydration must be corrected SLOWLY — maximum fall of 0.5 mmol/L/hr (or 10–12 mmol/L/24 h). Rapid correction causes cerebral oedema due to idiogenic osmoles. Use isotonic fluid, not hypotonic, initially.

Hypernatraemic dehydration: slow correction at ≤0.5 mmol/L/hr (≤10–12 mmol/L/24 h) over 48 h minimum. Use isotonic crystalloid initially; switch to hypotonic fluids cautiously. Rapid correction causes cerebral oedema (idiogenic osmoles). Monitor sodium every 4–6 hours.

Rapid correction of hypernatraemia with hypotonic fluid causes a rapid osmotic shift into the brain (which has generated idiogenic osmoles), leading to cerebral oedema and seizures. Use isotonic fluid and correct sodium gradually at ≤0.5 mmol/L/hr over 48 hours.

After two failed IV attempts, or if IV access is not achieved within 90 seconds in a critically ill child, IO access should be established immediately. IO provides equivalent fluid and drug delivery to IV access.

IO access protocol: establish IO after 2 failed IV attempts OR within 90 seconds if IV fails in a critically ill child. Site: proximal tibia (2 cm below tibial tuberosity). Confirm with saline flush. All IV drugs and fluids including blood products can be given IO. IO in distal femur is an alternative.

The paediatric emergency guideline: do not exceed two IV attempts or 90 seconds before moving to IO in a critically ill child. IO at the proximal tibia can be established in under 60 seconds and is equivalent to central venous access for all emergency medications and fluids.

Lethargic, very sunken eyes, skin pinch >2 seconds, unable to drink = severe dehydration, Plan C. Ringer's lactate: 30 mL/kg over 30 min then 70 mL/kg over 2.5 h. If IV not available, give ORS 20 mL/kg/hr via nasogastric tube for 6 hours.

IMNCI severe dehydration (Plan C): IV RL 30 mL/kg over 30 min (15 min for infants) then 70 mL/kg over 2.5 h (1 h for infants). Reassess hourly. If IV unavailable: ORS 20 mL/kg/hr via NG for 6 h or refer immediately. Start feeding as soon as child can drink.

Severe dehydration (≥2 of: lethargic/unconscious, sunken eyes, unable to drink, very slow skin pinch) = Plan C. IV Ringer's lactate: 30 mL/kg fast (30 min) then 70 mL/kg (2.5 h). Reassess at 1 h and 3 h. 5% dextrose/saline is NOT appropriate for volume resuscitation.

In children, peripheral veins on the dorsum of the hand, antecubital fossa, and dorsum of the foot are the first preferred sites for IV cannulation as they are superficial, accessible, and safe.

Paediatric peripheral IV sites in order of preference: (1) dorsum of hand, antecubital fossa, or dorsum of foot; (2) scalp veins (infants); (3) external jugular; (4) femoral (not truly peripheral — consider IO first in an emergency if these fail). Always choose the smallest gauge cannula that allows adequate flow.

Peripheral access is preferred first. Antecubital fossa and dorsum of hand/foot are the first-choice sites. Scalp veins are used in infants when limb veins are inaccessible. External jugular and femoral veins are central/deep and used as fallback options.