Intravenous fluids in pediatrics

A comprehensive review of Body compartments of fluid, physiology of fluid and electrolytes, different types of IV fluids and calculations.

1. Intravenous Fluids In Pediatrics Dr. Adeel Ashiq House Surgeon PSW SHL

2. 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

3. Water Composition by Age

4. Distribution of Fluid in Body

5. 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

6. 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

7. 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

8. 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

9. Composition of Different Fluids

10. 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

11. Distribution of N/S & R/L

12. Distribution of N/S & R/L Cell Interstitiu m Vessel 750ml 250ml

13. 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

14. Distribution of Dextrose Water

15. Distribution of Dextrose Water 666 ml 250ml 83ml Interstitium Cell Vessel

16. Albumin natural protein t1/2 = 20 days in the body but t1/2 = 1.6 hours in plasma 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 the capillary permeability is abnormal

17. 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 in albumin), defects of hemostasis

18. 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

19. Maintenance Fluid Replacement Holliday-Segar Method

20. 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

21. 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

22. Factors Decreasing Maintenance Fluid Requirements Skin: Mist tent, incubator (premature infants) Lungs: Humidified ventilator Mist tent Renal: Oliguria, anuria Misc : Hypothyroidism

23. 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

24. Deficit Calculation Potassium Deficit: 0.4x Body weight x ( Desierd conc – Current Conc. ) Maximum rate of infusion < 0.5 mEq /L

25. Deficit Calculation Bicarbonate Deficit : mEq =Base deficit x 0.3 x weight in Kg

26. Dehydration and Resucitation Concepts 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.

27. Phases of Resuscitation Phase I: Resuscitation : Goal: Restore circulation, re-perfuse brain, kidneys Mild-Moderate  20 mL/kg bolus given over 30 – 60 minutes Severe  May repeat bolus as needed (ideally up to 60ml/kg) Fluids – something isotonic such as NS or lactated ringers (LR)

28. Phases of Resuscitation Phase II: Replacement Phase Phase III: Stabilization Phase Goal: Replace deficit of fluids and electrolytes

29. 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

30. 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

31. 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.