Presentation on theme: "Fluids and Electrolytes in Pediatrics"— Presentation transcript:
1Fluids and Electrolytes in Pediatrics Kathleen Asas, MD.MPHInpatient PediatricsJan 2011
2ObjectivesTo review basics of maintenance fluid and electrolyte requirementsTo gain comfort in classification of dehydration and options for fluid supportTo perform case-based practice!
3Back to Basics….Fluid compartments Total body water= ICF + ECFTotal body water =60-75 % of Body weight
4Important ConceptsPlasma Osmolality= Concentration of solutes in bloodPlasma Osmolality= 2 x plasma (Na)Change in plasma osmolality --> change in ECF osmolality with water movement across cell membranesRemember: The body has an immediate need to restore intravascular volume over osmolality.
6Concepts Maintenance: Normal ongoing losses of fluids and electrolytes Deficit: Losses of fluids and electrolytes resulting from an illnessOn-going Losses: Requirement of fluids and electrolytes to replace ongoing losses
7Factors Increasing Maintenance Fluid Requirements Factors Decreasing Maintenance Fluid RequirementsFever-each 1 degree Celcius over 38 degrees increases maintenance fluid requirements by 12%HyperventilationIncreased temperature of the environmentBurnsOngoing losses-diarrhea, vomiting, NG tube outputSkin: Mist tent, incubator (premature infants)Lungs: Humidified ventilatorMist tentRenal: Oliguria, anuriaMisc: Hypothyroidism
8Goal of Fluid Therapy To prevent dehydration To prevent electrolyte abnormalitiesTo prevent protein degradationTo prevent acidosis and circulatory collapse
10Maintenance Electrolyte Requirements Na and K are the primary electrolytes that govern ECF and ICF osmolality.[Na] in ECF = mEq/L, negligible in ICF [K] in ICF = 150 mEq/L, negligible in ECFMaintenance Electrolyte Requirements:Na: 2-3 mEq/100ml water /dayOR 2-3 mEq/kg/day K: 1-2 mEq/100ml of water/dayOR 1-2mEq/kg/dayChloride: 2 mEq/100ml of water /day
14Concepts in Dehydration 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.
19Oral Rehydration: Key Concepts Mild to moderate dehydration may be managed successfully with oral rehydration in the majority of cases.Oral rehydration solutions should contain glucose and sodium in a ratio not to exceed 2:1Amount of rehydration solution to be given is based on the estimated percentage of dehydration by weight.
20Oral Rehydration Patient vomiting – 5-10mL Q 5-10 minutes and increase as toleratedMild Dehydration– Deficit replacement: 50 mL/kg over 4 hoursModerate Dehydration– Deficit replacement: 100 mL/kg over 4 hours
21Developing a Plan of Action Determine degree of dehydrationEstablish phases (total of 3 phases- Resuscitation, Replacement, and Stabilization)
22Phase II: Calculate maintenance & deficit fluid Phase I: Resuscitation using Isotonic Fluids (NS/LR) at 20ml/kg.Re-evaluation until urine output and dehydration signs improvedPhase II: Calculate maintenance & deficit fluidDetermine if Isotonic, Hypotonic or Hypertonic DehydrationHypertonicNa >150Replace fluids over 48hrs**HypotonicNa <130Isotonic130< Na <150
23Phase I – Resuscitation phase Goal: Restore circulation, re-perfuse brain, kidneysMild-Moderate 20 mL/kg bolus given over 30 – 60 minutesSevereMay repeat bolus as needed (ideally up to 60ml/kg)Fluids – something isotonic such as NS or lactated ringers (LR)
25Hypertonic Dehydration Phase 2: Replacement Phase Goal: Replace deficit of fluids and electrolytesand daily maintenanceAmount: Deficits + daily maintenance Fluid:Give over hoursIMPORTANT: Lower serum Na by no more than10-12 mEq/L per day or <0.5mEq/L/hr
26Hypertonic Dehydration Phase 3: Stabilization PhaseGoal: Replace ongoing losses and transition towards maintenance therapyAmount: Replacement + daily maintenance
27Exceptions: Severe Hyponatremia Serum Na < 120, CNS symptomsAmount of 3# NaCl: (Desired Na-observed Na) x wt x 0.6L/kg0.5mEq/LRemember 3% NaCl (0.5mEq Na/ml)The infusion should be given at a rate to increase the serum sodium by no more than 5 mEq/L/h and is often given more slowly over the course of 3–4 hDo not replace Na faster than meq/L per 24hrs. Why?Central pontine myelinosis: rapid brain cell shrinkage with rapid increase in ECF Na
28Steps in Fluid Replacement A. Phase I: Rapid Phase Restore intravascular volume a) Use Isotonic Fluid (NS/LR) b) Replace other components (Ca/glucose) separately based on documented deficit c) Volume: 10-20cc/kg; repeat up to 60cc/kg then re-evaluate B. Phase 2: Replacement Phase Determine type of dehydration based on Na-level (Isotonic, Hypotonic, or Hypertonic) a) Calculate 24-hr water needs Calculate maintenance water Calculate deficit water b) Calculate 24-hr electrolyte needs Calculate maintenance sodium and potassium Calculate deficit sodium and potassium c) Select an appropriate fluid (based on total water and electrolyte needs) Hypotonic and Isotonic Dehydration: Administer ½ calculated fluid during the 1st 8 hrs. Administer remainder over the next 16 hrs. C. Phase 3: Stabilization Replace ongoing losses as they occur (ex: diarrhea) a) Measure every 4-6 hrs and replace with appropriate fluids
29Exceptions: Treatment of Hypernatremic Dehydration Restore intravascular volume.Determine time for correction based on initial [Na]:[Na] mEq/L : 24 hr[Na] mEq/L: 48 hr[Na] mEq/L: 72 hr[Na] mEq/L: 84 hrAdminister fluid at a constant rate over the time for correctionTypical fluids: D5¼ NS or D5 ½ NS (with 20mEq/L KCl unless contraindicated)Follow serum NaSodium decreases too rapidly- Increase [Na] of IVF or decrease rate of IVFSodium decreased too slowly-Decrease [Na] of IVF or increase rate of IVF***Lower serum Na by no more than mEq/L per day
30Take Home MessageOral rehydration is a safe and effective intervention in patients with mild-to-moderate dehydration who are able to tolerate oral regimen.Fluid calculations are “best estimates.” Always monitor the effects of your interventions.Deficit fluid requirements are based on classification of dehydration.Hypotonic and isotonic dehydration are corrected in 8-hr and 16-hr blocks.Hypertonic dehydration is corrected based on Na level (usually over 48hrs).Slow correction of both hyponatremia and hypernatremia.
34Case 2A 4 year old male presents with a history of vomiting and diarrhea. He has had 10 episodes of vomiting (clear then yellow tinged) and 8 episodes of diarrhea. The diarrhea is now watery and the last few episodes have been red in color. The diarrhea odor is very foul. He feels weak.Exam: VS T 38.2 degrees (oral), P 110, R45, BP 90/65, oxygen saturation 100% in room air. Wt- 18 kg.He is alert and cooperative, but not very active. He is not toxic or irritable. His eyes are not sunken. TMs are normal. His oral mucosa is moist but he just vomited. His neck is supple. Tachycardic, Bowel sounds are normoactive.His overall color is slightly pale, his capillary refill time is 2 seconds over his chest, and his skin turgor feels somewhat diminished.
35Questions Based on clinical criteria, what is his % dehydration? Option 1 (Calculate PIW) 18kg/(1-0.05)= 18.9 (PIW)18.9kg – 18kg= 0.9 (100ml x 0.9)What method of fluid administration would you choose?The parents are insistent on IV fluids. What would be your steps in fluid administration?-Bolus of 20ml/kg-Re-assessment- IVF vs oral rehydration
36An IV is started and a chemistry panel is drawn. Phase I: resuscitation completed w/NS bolusPhase II: Determined Isotonic DehydrationMaint fluid: 1400mlMaint Na: 3 mEq/100ml 42 mEq Na/1400ml 30mEq/L NaMaint K: 2 mEq/100ml 28mEq K/1400ml-> 20mEq/L KDeficit fluid in 5% DHN: 18 x 0.05 x 1000-> 900ml -360ml 540ml< 3 days illness; 0.8 (900ml) 720ml (loss from ECF)0.2 (900lm) 180ml (loss from ICF)Deficit Na: [Na] in ECF × vol deficit [ECF}135 x 0.720L 97 mEq Na – 55mEq Na (received) 42 mEq NaDeficit K: [K] in ICF x proportion of fluid loss from ICF x deficit150 x L 27 mEq K1st Phase: NS bolus (360ml, 55mEq Na received)2nd phase:1st 8 hr: Replace 1/3 of maintenance Na + H20 + ½ deficit Na and H20:Na: 10 mEq + 21 mEq-> 31mEq/735ml -> 42 mEq Na/L465ml mlK: 7mEq + 14mEq 21mEq/735 28mEq/L K1st 8hrs: 735 ml of D5 1/3 NS + 25mEq 92ml/hrNext 16hrs: Replace 2/3 maint Na + H20 AND ½ deficit Na + H20:Na-> 20mEq+ 21mEq-> 41mEq Na/1205 ml 34mEq/L NaD5 1/4 NSK: 26mEq/1205ml 21mEq/L KNext 16hrs: 1205 ml of D5 1/4 NS + 20mEq K/L at 75ml/hrOral versus IV rehydration is discussed with his parents who indicate that they have tried oral hydration and are not happy with the results so they would likethe IV for him.An IV is started and a chemistry panel is drawn.Na 135, K3.4, Cl 99, bicarb 15.Wt-18kg.
37Question 5:DR is a 4 year old girl (16kg) who presents to the emergency room with fatigue,headache, generalized malaise, and severe gastrointestinal distress. The ER team gets a chem-7 and discovers her sodium to be 118. They would like to give 3% NaCl and ask you for a recommendation on how much to give, and at what rate.
38Answer Amount of 3# NaCl: (Desired Na-observed Na) x wt x 0.6L/kg 0.5mEq/LRemember 3% NaCl (0.5mEq Na/ml)Goal to increase Na by no more than 5mEq/LCalculation: ( ) x 16 x 0.6L/kg 134ml of 3% NaCl over 3-4 hrs0.5 mEq/L
395 kg child with 4-day h/o vomiting/diarrhea, 10% dehydration, [Na] of 128 mEq/L Fluid volumeNaK (replacement over 2 days)Maintenance5 x 100= 500ml3mEq/100ml fluid 15 mEq2mEq/100ml10 mEq KDeficit5 x 0.1 500ml[ECF] loss 0.6 (500ml) 300ml[ ICF] loss 0.4 (500ml) 200ml[Na] in ECF x propor. Loss x fluid deficit +[obs Na-desired Na x wt x prop Na loss]:135 x 0.3L + [ x 5 x 0.6]40mEq + 21 mEq 61 mEq[K] in ICF x prop loss x fluid deficit:150 x 0.2L 30 mEq KOngoing LossesReplace cc: ccAdd Na in proportion to expected concentration in lost fluid (e.g., stool, gastric contents)Add K in proportion to expected concentration in lost fluid (e.g., stool, gastric contentsTotal1st 8hrs:Next 16 hrs:1000ml165ml + 250ml:~ 400ml600ml= 76 mEq Na5mEq mEq 35mEq Na/400ml:165 ml ml mEq Na/L10mEq Na + 30 mEq Na 40 mEq Na/600ml 66mEq Na/L40 mEq K18 mEq KCl/L23 mEq KCl/LNext 16hrsD5 ½ NS + 20 mEq 50ml/hrD5 ½ NS + 20mEq/L 35-40ml/hr
40Determine adequate fluids for 7-kg child with 15%, Na=160 Fluid volumeNaK (replacement over 2 days)Maintenance700ml/day3mEq/100ml fluid 21mEq Na2mEq/100ml 14mEq KDeficit7 x 0.15= 1050mlSFD= 630mlFWD-420 mlFree H20 deficit: 7kg x 4ml/kg x [Serum Na-desired Na] 420mlNa: [Na in ECF] x prop Na loss x [Solute deficit][135 x 0.6] x [ ]=51 mEq Na[K] in ICF x prop loss x fluid deficit 38mEqOngoing LossesReplace cc: ccAdd Na in proportion to expected concentration in lost fluid (e.g., stool, gastric contents)Add K in proportion to expected concentration in lost fluid (e.g., stool, gastric contents1st 24hr24-hr maint + ½ Free H20 deficit + SFD: 1540mlSolute Fluid + Elect DeficitsTotalFluid Order:Maint Na + Def Na21mEq mEq 72 mEq72mEq/1.54L 47 mEq Na/LD5 1/3 NS + 30mEq 64ml/hr14mEq38mEq52mEq/1.54L34mEq K/LNext 24hrs24-hr maint + ½ FWD700ml + 210ml-> 910ml21mEq Na/0.91L 23mEq Na/LD5 ¼ NS + 15mEq 38ml/hr14mEq/0.91ml 15mEq K/L
41ReferencesFleisher, G. et al. (2005). Renal and Electrolyte Emergencies. In Cronan, K. & Kost (Eds), Textbook of Pediatric Emergency Medicine.Kleigman, R. et al. Nelson Essentials of Pediatrics. Chapter 32: Fluids and Electrolytes. 5th edition. ppRobertson, J. & Shilfoski, N. (2005). Fluids and Electrolytes. The Harriet Lane Handbook. (pp ).Sykes, R. (2007). Pediatric Fluids and Electrolytes. [PowerPoint slides].