fluids&lytes pediatric

7/28/2019 Fluids&Lytes Pediatric

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Fluids & Electrolytes

Pediatric Emergency Medicine

Boston Medical Center

Boston University School of Medicine


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Objectives

To discuss:

Maintenance Fluids and Electrolyte Requirements

Types of Dehydration

Management of Dehydration

Electrolyte Abnormalities


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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


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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


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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


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Regulation of Body Fluids and

ElectrolytesAldosterone

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


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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


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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 meqKCl/liter

Up to age 2-3 years: D5 0.2 NS + 20 meqKCl/liter

D5 = 50 gm/liter = 5 g/dl

Newborns often require D10 = 100 gm/liter = 10gm/dl


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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


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General Principles:

Supply Maintenance Requirements

Correct volume and electrolyte deficit

Replace ongoing abnormal losses


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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


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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.OFor cholera use

90 20 80 HCO3 Glucose 2


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Management of Dehydration:

IV Replacement of Fluid Deficit Based on %

Dehydration:

Example: 5 kg child who is 6% dehydrated: 5 x60cc/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


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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 = 300ccfor 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


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Hyponatremia

Predisposing Factors

Diabetes mellitus (hyperglycemia)

Cystic fibrosis

CNS disorders ( SIADH)

Gastroenteritis

Excessive water intake (formula dilution) Diuretics (thiazides and furosemide)

Renal disease


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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


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Hyponatremia

Acute Hyponatremia (


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Hyponatremia

Chronic Hyponatremia (>48 hours)

Lethargy

Confusion

Muscle cramps

Neurologic Impairment


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Hyponatremia

Management Na Deficit:

Na Deficit = (Na Desired - Na observed) x 0.6x body weight(kg)

Replace half in first 8 hours and the rest in thefollowing 16 hours

Rise in serum Na should not exceed 2 mEq/L/h toprevent Central Pontine Myelinolysis (? Existencein children)

In cases of severe hyponatremia (


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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


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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


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Hypernatremia

Signs and symptoms

Disturbances of consciousness

Lethargy or Confusion

Neuromuscular Irritability

Muscle twitching, hyperreflexia

Convulsions Hyperthermia

Skin may feel thick or doughy


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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/hror ~ 10 mEq/day: Faster correction can result in

Cerebral Edema


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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


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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


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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 DKAIntestinal fistula Gentamicin, Hyperaldosteronism

Laxatives Amphotericin Adrenal adenomas

Enemas Diuretics Mineralocorticoids

Bartter's syndrome

Bartters syndrome: Hypereninemia and hyperaldosteronism


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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


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Hyperkalemia

Differential Diagnosis

Pseudohyperkalemia - from blood hemolysis

Metabolic Acidosis

Chronic Renal Failure

Congenital Adrenal Hyperplasia

Females = Usually Dx at birth - AmbiguousGenitalia

Males = Dehydration, hyponatremia, hyperkalemia

Medications

ACE inhibitors and NSAIDs


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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)


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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

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