This document discusses fluid and electrolyte regulation and abnormalities in pediatrics. It covers the composition of body water compartments, daily fluid requirements, types of dehydration and their management, as well as electrolyte abnormalities including hyponatremia, hypernatremia, hypokalemia, and hyperkalemia. Signs and symptoms and treatment approaches are provided for each electrolyte imbalance.

1. Fluids & Electrolytes
Pediatric Emergency Medicine
Boston Medical Center
Boston University School of Medicine

2. Objectives
 To discuss:
 Maintenance Fluids and Electrolyte Requirements
 Types of Dehydration
 Management of Dehydration
 Electrolyte Abnormalities

3. Composition of Body
Compartments
 Total Body Water (TBW)= 50-75% of Total Body
Mass
 TBW = Intracellular Fluid (ICF) + Extracellular Fluid (ECF)
 ICF = 2/3 of TBW
 ECF = 1/3 of TBW -- 25% of body weight
 ECF = Plasma (intravascular) + Interstitial fluid

4. Body Water Compartments
Related to Age
0
10
20
30
40
50
60
70
80
0 years 1 year 10 years 20 years
TBW
ICF
ECF

5. Regulation of Body Fluids and
Electrolytes
 Mechanism to Regulate ECF volume
 Anti-Diuretic Hormone (ADH)
• Kidney = Increase water reabsorption
• ADH secretion is regulated by tonicity of body
fluids
 Thirst
• Not physiological stimulated until plasma
osmolality is >290

6. Regulation of Body Fluids and
Electrolytes
 Aldosterone
• Released from the adrenal cortex
– Decrease circulating volume
– Stimulation by Renin-Angiotensin Aldosterone axis
– Increase plasma K
• Enhanced renal reabsorption of Na in
exchange for K (>Na = expansion of ECF)
 Atrial Natriuretic Factor
• Secreated by the cardiac atrium in response to
atrial dilatation (regulates blood volume)
• Inhibits Renin secretion
• Increase GFR and Na excretion

7. Daily Maintenance
Requirements

8. 4cc, 2cc, 1cc rule
 4 cc for the first 10 kg
 2 cc for the next 10 kg
 1 cc for each kg after
 Example:
• 27 kg child
– 4 cc for the first 10 kg = 40cc
– 2 cc for the next 10 kg = 20cc
– 1 cc for each kg after = 7 cc
67 cc/hr

9. Maintenance Requirements
 Maintenance Fluids: weight dependent
& age dependent:
 (NS =0.9% Saline =154 meq Na/liter)
 age >2 -3 years: D5 0.5 NS + 20 meq
KCl/liter
 Up to age 2-3 years: D5 0.2 NS + 20 meq
KCl/liter
• D5 = 50 gm/liter = 5 g/dl
• Newborns often require D10 = 100 gm/liter = 10
gm/dl

10. Dehydration
 Epidemiology:
 One of the most common medical problems
 In the U.S. - 10% of all pediatric admissions
 Worldwide, over 3 million children under 5
years die from dehydration

11. Estimation of Dehydration
Mild Moderate Severe
Weight Loss 3-5% 6-9% >10%
Blood pressure Normal Orthostatic Shock
Pulse Normal Increase Tachycardic
Behavior Normal Irritable Lethargic
Membranes Moist Dry Parched
Tears Present Decrease Absent
Cap. Refill 2 seconds 2-4 seconds >4 seconds
Urine SG >1.020 >1.030 Oliguria

12. Dehydration
 Classification
 Isotonic
• Serum Sodium 130-150 mEq
 Hypotonic
• Serum Sodium < 130 mEq
 Hypertonic
• Serum Sodium >150 mEq

13. Management of Dehydration
 General Principles:
 Supply Maintenance Requirements
 Correct volume and electrolyte deficit
 Replace ongoing abnormal losses

14. Management of Dehydration
 Oral Rehydration:
 Effective for mild and some moderate
dehydrations
 Child may be able to tolerate PO intake
 Small aliquots as tolerated
• Mild: 50 cc/kg over 4 hours
• Moderate: 100 cc/kg over 4 hours
 2 types of oral solution
• Maintenance
• Rehydration

15. Commercial Oral Solutions
Na mEq/L K mEq/L Cl mEq/L Base CHO %
Maintenance
 Reosol 50 20 50 Citrate Glucose 2
 Ricelyte 50 25 45 Citrate Rice syrup 3
 Pedialyte 45 20 35 Citrate Glucose 2.5
Rehydration
 Rehydralyte 75 20 65 Citrate Glucose 2.5
 W.H.O
For cholera use
90 20 80 HCO3 Glucose 2

16. Management of Dehydration:
IV
 Replacement of Fluid Deficit Based on %
Dehydration:
 Example: 5 kg child who is 6% dehydrated: 5 x
60cc/kg
• fluid deficit (cc) = wt x % dehydration
• fluid deficit (cc) = wt in kg (1000cc/kg) x (1/100)
estimate of dehydration
• fluid deficit (cc) = wt x 10 x estimate of dehydration
• fluid deficit (cc) = 5 x 10 x 6
• fluid deficit (cc) = 300 cc

17. Management of Dehydration:
IV
 Initial: NS or LR 20 cc/kg Bolus in first hour
 Then Remainder of Deficit
• In previous example: total fluid deficit = 300cc
for 5 kg child who is 6% dehydrated = 60cc/kg
• Replacement:
– first hour: 20 cc/kg = 20 x 5 = 100 cc
– replace the rest: 40 cc/kg or 300 - 100 = 200 cc
– The type of fluid used and the rate of infusion
depends on the age and Na status of the patient:
» for isonatremic dehydration: correct deficits of
next 7 hours
» 200cc over 7 hours = 28 cc/hr

18. Hyponatremia
 Predisposing Factors
 Diabetes mellitus (hyperglycemia)
 Cystic fibrosis
 CNS disorders ( SIADH)
 Gastroenteritis
 Excessive water intake (formula dilution)
 Diuretics (thiazides and furosemide)
 Renal disease

19. Hyponatremia
 Hyponatremic Dehydration
 Hypovolemic Hyponatremic Dehydration
• High urine output and Na excretion
• Increase in atrial natriuretic factor
 Euvolemic Hyponatremic Dehydration
• ADH mediated water retention
 Hypervolemic Hyponatremic Dehydration
• Edematous disorder (nephrotic syndrome, CHF,
cirrhosis)
• Water intoxication

20. Hyponatremia
 Acute Hyponatremia (<24 hours)
 Early Onset (Serum Sodium <125 meq/L)
• Nausea
• Vomiting
• Headache
 Later or Severe (Serum Sodium <120 meq/L)
• Seizure
• Coma
• Respiratory arrest

21. Hyponatremia
 Chronic Hyponatremia (>48 hours)
 Lethargy
 Confusion
 Muscle cramps
 Neurologic Impairment

22. Hyponatremia
 Management
 Na Deficit:
• Na Deficit = (Na Desired - Na observed) x 0.6
x body weight(kg)
 Replace half in first 8 hours and the rest in the
following 16 hours
 Rise in serum Na should not exceed 2 mEq/L/h to
prevent Central Pontine Myelinolysis (? Existence
in children)
 In cases of severe hyponatremia (<120 mEq) with
CNS symptoms:
• 3% NaCl 3-5 ml/kg IV push for hyponatremia
induced seizures
– 6 ml/kg of NaCl will raise serum Na by 5 mEq/L

23. Hypernatremia
 Hypernatremia leads to hypertonicity
 Increase secretion of ADH
 Increase thirst
 Patients at risk
 Inability to secrete or respond to ADH
 No access to water

24. Hypernatremia
 Etiology
 Pure water depletion
• Diabetes insipidus (Central or Nephrogenic)
 Sodium excess
• Salt poisoning (PO or IV)
 Water depletion exceeding Na depletion
• Diarrhea, vomiting, decrease fluid intake
 Pharmacologic agents
• Lithium, Cyclophosphamide, Cisplatin

25. Hypernatremia
 Signs and symptoms
 Disturbances of consciousness
• Lethargy or Confusion
 Neuromuscular Irritability
• Muscle twitching, hyperreflexia
 Convulsions
 Hyperthermia
• Skin may feel thick or doughy

26. Hypernatremia
 Management
 Normal Saline or Ringer lactate to restore volume
 Hypotonic solution (D5 1/4 NS) to correct calculated
deficit over 48 hours
• Water Deficit
– Normal body H20 - Current body H20
• Current body water
– 0.6 x body weight (kg) x Normal Na/Observed Na
• Normal Body water
– 0.6 x body weight (kg)
 Decrease Na concentration at a rate of 0.5 mEq/hr
or ~ 10 mEq/day: Faster correction can result in
Cerebral Edema

27. Potassium
 Most abundant intracellular cation
 Normal serum values 3.5-5.5 mEq
 Abnormalities of serum K are potentially life-
threatening due to effect in cardiac function

28. Hypokalemia
 Diagnosis
 Symptoms
• Arrhythmias
• Neuromuscular excitability (hyporreflexia, paralysis)
• Gastrointestinal (decreased peristalsis or ileus)
 Serum K < 3mEq/L
 ECG:
• Flat T waves
• Short P-R interval and QRS
• U waves

29. Hypokalemia
Nutritional GI Loss Renal Loss Endocrine
Poor intake Diarrhea Renal tubular acidosis Insulin therapy
IVF low in K Vomiting Chronic renal disease Glucose therapy
Anorexia Malabsorbtion Fanconi's syndrome DKA
Intestinal fistula Gentamicin, Hyperaldosteronism
Laxatives Amphotericin Adrenal adenomas
Enemas Diuretics Mineralocorticoids
Bartter's syndrome
Bartter’s syndrome: Hypereninemia and hyperaldosteronism

30. Hypokalemia
 Management:
 Cardiac Arrhythmias or Muscle Weakness
• KCl IV (cardiac monitor)
 PO K - Depend of etiology
• Hypophoshatemia = KPO4
• Metabolic acidosis = KCl
• Renal tubular acidosis = K citrate

31. Hyperkalemia
 Differential Diagnosis
 Pseudohyperkalemia - from blood hemolysis
 Metabolic Acidosis
 Chronic Renal Failure
 Congenital Adrenal Hyperplasia
• Females = Usually Dx at birth - Ambiguous
Genitalia
• Males = Dehydration, hyponatremia, hyperkalemia
 Medications
• ACE inhibitors and NSAID’s

32. Hyperkalemia
 Diagnosis:
 Symptoms
• Cardiac Arrhythmias
• Paresthesias
• Muscle weakness or paralysis
 ECG
• Peaked T waves
• Short QT interval (K>6 mEq)
• Depressed ST segment
• Wide QRS (K>8 mEq)

33. Hyperkalemia
 Management
 Close cardiac monitoring
 Life -threatening hyperkalmia
• Intravenous Calcium - rapid onset, duration< 30 min
• NaHCO3 or glucose and insulin
 Ion exchange resins
• Sodium polystyrene sulfonate (Kayexelate)
– PO or Enema
 Hemodyalisis