Fluids and Electrolytes Flashcards
Definition of dehydration
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
Causes of dehydration
*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)
In which population does dehydration occur the most?
Neonates and infants
Severity of dehydration in infants (%)
Mild: 1-5%
Moderate: 6-9%
Severe: >10%
>/=15% = SHOCK
Severity of dehydration in older children (%)
Mild: 1-3%
Moderate: 4-6%
Severe: >6%
>/=9% = SHOCK
Severity of dehydration (% estimated) equation
[(pre-illlness weight (kg) - illness weight (kg)) / pre-illness weight (kg)] x100
Fluid deficit (L) equation
% dehydration x pre-illness weight (kg) x 100
Signs/symptoms of MILD dehydration:
Pulse
SBP
UOP
Buccal mucosa
Anterior fontanelle
Eyes
Skin turgor/cap. refill
Skin (<12 months)
Tears
Mental status
Thirst
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
Signs/symptoms of MODERATE dehydration:
Pulse
SBP
UOP
Buccal mucosa
Anterior fontanelle
Eyes
Skin turgor/cap. refill
Skin (<12 months)
Tears
Mental status
Thirst
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
Signs/symptoms of SEVERE dehydration:
Pulse
SBP
UOP
Buccal mucosa
Anterior fontanelle
Eyes
Skin turgor/cap. refill
Skin (<12 months)
Tears
Mental status
Thirst
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
Goal of therapy for dehydration
Restore fluid and electrolyte balance in combination with early introduction of appropriate food and oral liquids, as tolerated
Mode of rehydration: MILD
Oral rehydration therapy
Mode of rehydration: MODERATE
Oral rehydration therapy
Mode of rehydration: SEVERE
Intravenous fluid
Also for shock, failure of ORT, coma/unconscious, abdominal emergency
ORT Dosing
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
IVF dosing for rehydration
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
Monitoring parameters of rehydration therapy
Normalization of blood pressure
Adequate urine output for age/weight
Improvement in clinical signs/symptoms of dehydration
Normalization of serum electrolytes/laboratory parameters
Components of IVF
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
Additional electrolytes in IVF
Magnesium, phosphate, calcium based on individual needs
Negative anions in IVF
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
Maintenance IVF for neonates
< 1500 g: 130-150 mL/kg/day
1500-2000 g: 110-130 mL/kg/day
Full term: 80-140 mL/kg/day
Maintenance IVF for infants/children/adolescents
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)
Management of gastroenteritis
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
