Fluids and Electrolytes

Question 1

Definition of dehydration

Answer 1

A potentially harmful reduction in the overall fluid/water in the body, which occurs when intake of fluid/electrolytes is less than the loss of fluid/electrolytes

Question 2

Causes of dehydration

Answer 2

*Fever
GI losses: *Viral gastroenteritis (most common), bacterial/parasitic infections, DKA, inborn errors of metabolism, intestinal obstruction/history of surgical resection, chronic disease (Crohn’s, CF, etc.)
Sweating/Excessive heat/Burns
Polyuria (DKA)
Imbalance in regulation of sodium/water (DI,SIADH - hormonal)

Question 3

In which population does dehydration occur the most?

Answer 3

Neonates and infants

Question 4

Severity of dehydration in infants (%)

Answer 4

Mild: 1-5%
Moderate: 6-9%
Severe: >10%
>/=15% = SHOCK

Question 5

Severity of dehydration in older children (%)

Answer 5

Mild: 1-3%
Moderate: 4-6%
Severe: >6%
>/=9% = SHOCK

Question 6

Severity of dehydration (% estimated) equation

Answer 6

[(pre-illlness weight (kg) - illness weight (kg)) / pre-illness weight (kg)] x100

Question 7

Fluid deficit (L) equation

Answer 7

% dehydration x pre-illness weight (kg) x 100

Question 8

Signs/symptoms of MILD dehydration:
Pulse
SBP
UOP
Buccal mucosa
Anterior fontanelle
Eyes
Skin turgor/cap. refill
Skin (<12 months)
Tears
Mental status
Thirst

Answer 8

Pulse: normal/increased
SBP: normal
UOP: decreased
Buccal mucosa: slightly dry
Anterior fontanelle: normal
Eyes: normal
Skin turgor/cap. refill: normal
Skin (<12 months): normal
Tears: normal
Mental status: normal
Thirst: drinks normally

Question 9

Signs/symptoms of MODERATE dehydration:
Pulse
SBP
UOP
Buccal mucosa
Anterior fontanelle
Eyes
Skin turgor/cap. refill
Skin (<12 months)
Tears
Mental status
Thirst

Answer 9

Pulse: Tachycardia
SBP: Normal, low
UOP: Little/no output
Buccal mucosa: Dry
Anterior fontanelle: Sunken
Eyes: Sunken
Skin turgor/cap. refill: Delayed, cool, pale
Skin (<12 months): Cool
Tears: Decreased
Mental status: Normal to listless
Thirst: Thirsty

Question 10

Signs/symptoms of SEVERE dehydration:
Pulse
SBP
UOP
Buccal mucosa
Anterior fontanelle
Eyes
Skin turgor/cap. refill
Skin (<12 months)
Tears
Mental status
Thirst

Answer 10

Pulse: Rapid and weak
SBP: Decreased, very low
UOP: Oliguria
Buccal mucosa: Parched
Anterior fontanelle: Very sunken
Eyes: Very sunken
Skin turgor/cap. refill: Very delayed, cool, and mottled
Skin (<12 months): Acrocyanosis
Tears: No tears
Mental status: Normal to lethargic/comatose
Thirst: Drinks poorly, unable to drink

Question 11

Goal of therapy for dehydration

Answer 11

Restore fluid and electrolyte balance in combination with early introduction of appropriate food and oral liquids, as tolerated

Question 12

Mode of rehydration: MILD

Answer 12

Oral rehydration therapy

Question 13

Mode of rehydration: MODERATE

Answer 13

Oral rehydration therapy

Question 14

Mode of rehydration: SEVERE

Answer 14

Intravenous fluid
Also for shock, failure of ORT, coma/unconscious, abdominal emergency

Question 15

ORT Dosing

Answer 15

Mild: 50mL/kg over 4 hour period, reassess status every 2 hours
Moderate: 100mL/kg over 4 hour period, reassess status hourly
Add 10mL/kg for each loose stool/vomiting episode for both mild/moderate

Question 16

IVF dosing for rehydration

Answer 16

Phase I: 10-20 mL/kg/dose of NS or LR over 30-60 minutes as IV bolus, repeat up to 3 times based on signs/symptoms
Phase II: First 8 hours, calculate and replace fluid deficit; next 16 hours, calculate and provide maintenance rate

Question 17

Monitoring parameters of rehydration therapy

Answer 17

Normalization of blood pressure
Adequate urine output for age/weight
Improvement in clinical signs/symptoms of dehydration
Normalization of serum electrolytes/laboratory parameters

Question 18

Components of IVF

Answer 18

Sodium
Must be included to avoid sodium shifts/hyponatremia
NS (0.9%) = isotonic
1/2 NS (0.45%) = hypotonic
1/4 NS (0.225%) = very limited, certain circumstances only

Dextrose
D5W = 5%
D10W = 10%|used in neonates, infants with hypoglycemia
>12.5% - requires central line

Potassium
Standard concentration: 20 mEq/L
Commercially available bags range from 10-40 mEq/L
Can compound higher concentration if needed
Use with caution in patients with renal failure and in neonates

Question 19

Additional electrolytes in IVF

Answer 19

Magnesium, phosphate, calcium based on individual needs

Question 20

Negative anions in IVF

Answer 20

When providing cations (Na+, K+), also provides negative anion (chloride or acetate)
Standard: *Chloride
Can compound with “potassium acetate” under certain circumstances such as DKA

Question 21

Maintenance IVF for neonates

Answer 21

< 1500 g: 130-150 mL/kg/day
1500-2000 g: 110-130 mL/kg/day
Full term: 80-140 mL/kg/day

Question 22

Maintenance IVF for infants/children/adolescents

Answer 22

4-2-1 *hourly requirement
<10 kg: 4 mL/kg/hr
10-20 kg: 40 mL/hr + 2 mL/kg/hr x (weight-10kg)
>20 kg: 60 mL + 1 mL/kg/hr x (weight - 20 kg)

Holliday-Segar: *24 hour requirement
<10 kg: 100 mL/kg
10-20 kg: 1000 mL + 50 mL/kg x (weight - 10 kg)
>20 kg: 1500 mL + 20 mL/kg x (weight - 20 kg)

Question 23

Management of gastroenteritis

Answer 23

Ondansetron: 5-HT3 receptor antagonist, blocks serotonin at peripheral vagal nerve terminals and at central chemoreceptor trigger zone.
Provide a single dose to assist patient in tolerating ORT
Dose = 0.15-0.3 mg/kg/dose in patients > 6 months of age
ADEs: Risk of QTc prolongation, arrhythmias
Available as OS, tablet, ODT, IV

Not recommended: Probiotics, zinc (unless deficient), antidiarrhea medications