Intravenous Fluids In Pediatrics
Dr. Adeel AshiqHouse Surgeon
PSW SHL
Objectives
• Physiology of Fluid Distribution• Different types of IV fluids• Distribution of IV Fluids in Body
Compartments• Maintenance Fluid Calculation• Calculation of Deficits• Phases of Resuscitation• Special circumstances
Water Composition by Age
Distribution of Fluid in Body
Total Body Water
ECF(1/3rd)
Interstitial (2/3rd)
Intravascular (1/3rd)
ICF(2/3rd)
Diff. In ICF & ECF
Component ECF ICF
Sodium 142 14
Potassium 4.2 140
Chloride 108 4
Bicarbonate 24 10
Magnesium 0.8
Nutrient O2, Amino acid, Fatty acid Proteins
Physiology of fluid compartments
Capillary membrane• Between plasma and interstitium• Allows free passage of electrolytes• Restricts passage of protein molecules• Colloid osmotic pressure draws fluid in
capillary• Hydrostatic fluid pushes fluid out
Physiology of fluid compartments
Cell membrane• Barrier between ICF and ECF• Freely permeable to water but not to sodium• Water moves in either direction depending
upon osmolarity
Types Of Fluids
CRYSTALLOIDS:• Contain Na as major osmotically active particle• Will cross a semi-permeable membrane• E.g. Normal Saline, Ringer Lactate
COLLOIDS:• Contain high molecular weight substancces• Are largely unable to cross a semi-permeable membrane• Albumin, Dextran, Gelatin
Composition of Different Fluids
0.9% Normal Saline(‘Salt and water’)
• Iso-osmolar (compared to normal plasma)• Contains: 154 mmol/l of sodium and chloride • Stays almost entirely in the extracellular space,
so for 100ml blood loss – need to give 400ml normal saline (only 25% remains intravascular)
• Principal fluid used for intravascular resuscitation and replacement of salt loss e.g diarrhoea and vomiting
Distribution of N/S & R/L
Distribution of N/S & R/L
Cell Interstitium Vessel
750ml
250m
l
5% Dextrose (D5W)“Sugar and Water”
• Commonly used ‘maintenance’ fluid in conjuction with normal saline
• Provides some calories (approximately 10% of daily requirements)• Regarded as ‘electrolyte free’• Distribution: <10% Intravascular; > 66% intracellular• When infused is rapidly redistributed into the intracellular space;
Less than 10% stays in the intravascular space therefore it is of limited use in fluid resuscitation.
• For every 100ml blood loss – need 1000ml dextrose replacement [10% retained in intravascular space
Distribution of Dextrose Water
Distribution of Dextrose Water
666 ml 250ml
83m
l
InterstitiumCell Vessel
Albumin
• natural protein• t1/2 = 20 days in the body but t1/2 = 1.6 hours inplasma• 10% leaves the vascular space within 2 hours,
95% within 2 days• causes 80-90% of our natural oncotic pressure• stays within the intravascular space unless thecapillary permeability is abnormal
Albumin
• 5% solution- isooncotic; 10% and 25% solutions -hyperoncotic• expands volume 5x its own volume in 30 minutes• effect lasts about 24-48 hours• Side Effects- volume overload, fever (pyrogens inalbumin), defects of hemostasis
Types of Fluid Replacement
• Maintenance: Normal ongoing losses of fluids and electrolytes
• Deficit: Losses of fluids and electrolytes resulting from an illness
• On-going Losses: Requirement of fluids and electrolytes to replace ongoing losses
Maintenance Fluid Replacement
Holliday-Segar Method
Maintenance Electrolyte Requirements
• Na: 2-3 mEq/100ml water /day OR 2-3 mEq/kg/day
• K: 1-2 mEq/100ml of water/day OR 1-2mEq/kg/day• Chloride: 2 mEq/100ml of water /day
Factors Increasing Maintenance Fluid Requirements
• Fever-each 1 degree Celcius over 38 degrees increases maintenance fluid requirements by 12%
• Hyperventilation• Increased temperature of the environment• Burns• Ongoing losses-diarrhea, vomiting, NG tube
output
Factors Decreasing Maintenance Fluid Requirements
• Skin: Mist tent, incubator (premature infants)• Lungs: Humidified ventilator• Mist tent• Renal: Oliguria, anuria• Misc: Hypothyroidism
Deficit Calculation
Sodium Deficit:
0.6x Body Weight x (Desired conc. – Current conc.)
• Do not replace Na faster than 10-12 meq/L per 24hrs. Why?Central pontine myelinosis: rapid brain cell shrinkage with rapid increase in ECF Na
Deficit Calculation
Potassium Deficit:
0.4x Body weight x ( Desierd conc – Current Conc. )
• Maximum rate of infusion < 0.5 mEq/L
Deficit Calculation
Bicarbonate Deficit :
mEq =Base deficit x 0.3 x weight in Kg
Dehydration and ResucitationConcepts
• Initial loss of fluid from the body depletes the extracellular fluid (ECF).
• Gradually, water shifts from the intracellular space to maintain the ECF, and this fluid is lost if dehydration persists.
• Acute Illness (<3 days ): 80% of the fluid loss is from the ECF and 20% is from the intracellular fluid (ICF).
• Prolonged Illness (> 3 days): 60% fluid loss from ECF and 40% loss from ICF.
Phases of Resuscitation
Phase I: Resuscitation :• Goal: Restore circulation, re-perfuse brain, kidneys• Mild-Moderate 20 mL/kg bolus given over 30 – 60 minutes
• SevereMay repeat bolus as needed (ideally up to 60ml/kg)
• Fluids – something isotonic such as NS or lactated ringers (LR)
Phases of Resuscitation
• Phase II: Replacement Phase• Phase III: Stabilization Phase
Goal: Replace deficit of fluids and electrolytes
Special Circumstances
Burn :
• The Parkland formula for the total fluid requirement in 24 hours is as follows:
• 4ml x TBSA (%) x body weight (kg);• 50% given in first eight hours;• 50% given in next 16 hours
Special Circumstances
Term Neonates :• Day 1: 50ml/kg/day• Day 2: 70-80ml/kg/day• Day3 : 80-100ml/kg/day• Day4: 100-120ml/kg/day• Day5: 120-150ml/kg/day
Important Guide Lines
• Measure serum electrolyte and blood glucose when starting IV fluids and at least every 24 hours thereafter.
• If Term neonate need IV Fluid for routine maintenance give isotonic crystalloid containing sodium 131-154mmol/L with 5-10% Glucose.
Top Related