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Body Fluids

Body Fluids. Total Body Water = Extracellular Fluid (ECF) + Intracellular Fluid ( ICF) ECF = Plasma + Interstitial Fluid Total Body Water expressed in terms of % body weight (adolescent or adult): ICF (30-40%) Interstitial (15 %) Plasma 5% & Infants- 8%. Change in Body Composition.

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Body Fluids

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  1. Body Fluids • Total Body Water = Extracellular Fluid (ECF) + Intracellular Fluid (ICF) • ECF = Plasma + Interstitial Fluid • Total Body Water expressed in terms of % body weight (adolescent or adult): • ICF (30-40%) • Interstitial(15%) • Plasma5% & Infants- 8%

  2. Change in Body Composition

  3. Change in Body Composition

  4. dehydration • Child: Mild- 5% weight loss Moderate 10 15-severe or shock • 3%/6%/9% old child & adults

  5. dehydration • Mild: thirsty, minimal clinical picture • Moderate: tachycardia, sunken eyes, dry mucous membranes, depressed fontanel, decreased urination (???- only 20% of "oliguric" patients have dehydration!), ± prolonged capillary refill • Severe: blood pressure drop

  6. dehydration • Isotonic dehydration • hypertonic (Na≥150) • hypotonic (Na≤130)

  7. dehydration • Acute< 3 days 75-100% of fluids losses is from ECF (primarily Na loss, less K loss) • Subacute or chronic> 3 days 65-70% of losses from ECF and 30% from ICF with greater level of potassium loss

  8. Treatment of dehydration • Fluids!!!!! • Etiologic treatment

  9. Treatment of dehydration • Rout of fluids administration: enteral and parenteral

  10. Treatment of dehydration • Oral/PZ- preferable & most physiologic type • Hypotonic type: ORS by 40-60meq Na/20 meq K and 2.5D for non choleric patients • Medium type: 70meq Na • High solute type: 60-90Na for cholera 1 cc/kg for mild and 2cc/kg for moderate dehydration for 4 h every 5 minutes

  11. Dehydration treatment Oral rehydration contraindications: • intractable vomiting • impaired consciousness • aspirations risk • bowel obstruction

  12. Treatment of dehydration • Parenteral: • Subcutaneous with recombinant hyaluronidase adjuvant • IV/iofor failed ORS or Moderate-Severe dehydration

  13. IV dehydration correction • 3 phases • Emergent • Corrections • Maintenance and ongoing losses

  14. Emergent phase of fluid replacement correction of perfusion failure and intravascular deficit by bolus of isotonic fluids 0.9 NaCl±D5 or Ringer lactate 20ml/kg (previous mass!) • Bolus- within minutes! • Repeat boluses until stable

  15. Emergent phase • Patient with decreased oncotic pressure (nephrotic syndrome, protein-loosing entheropathy, burns, cirrhosis)- may give 5% albumin • DKA- start 10 ml/kg • Premature and small newborns- 10 ml/kg • Suspected cardiogenic shock – 10ml/kg

  16. Second phase- deficits correction Deficits: H2O+ Na+ K± Ca

  17. Deficits correction • Assess degree of dehydration • Assess type of dehydration • Assess length of dehydration

  18. Deficits correction • FIRST - calculate the amount of fluid you need • NEXT - calculate how much sodium and potassium you need • FINALLY - pick a fluid based upon what is commercially available if you can

  19. Deficits correction Persistent deficits= previous loss- boluses Most accurate method of water deficit estimation- weight loss Other method: Calculated previous weight- current weight Calculated weight= current+ estimated fluid loss Estimated fluid loss- by percent of dehydration

  20. Isotonic dehydration • Water deficit- weight loss or estimated weight loss • Sodium deficit

  21. Isotonic dehydrationsodium deficit total body water(normal)*140meq/l- current TBW*current [Na]= Na deficit

  22. Isotonic dehydration • Normal TBW= normal body mass*K k~0.75 neonates, 0.65 toddlers, 0.6w &0.5m • ??????Really Current TBW~ current mass (k- estimated percent of dehydration/10)

  23. 10 kg infant with 10% dehydration- 1l loss Sodium deficit= 1*140 meq/ml Sodium maintenance= 3meq/100 ml of water*daily fluids

  24. Isotonic dehydration • Replacement and maintenance by isotonic or ½ NS based fluids • Give 100-70% of deficit at 1st day • Give 1st half of day fluids amount at 1st 8h and rest at 16h • New recommendations- to give NS based fluids to prevent iatrogenic hyponatremia

  25. Ongoing Repletion and Maintenance Therapy • Once the patient is stable Persistent deficits+ ongoing losses+ maintenance fluids

  26. Fluid maintenance: Holliday Segar formula • 1st 10kg- 100 ml/kg • 2nd 10kg- 50ml/kg • Others- 20ml/kg • ~400 ml/m²/d+ renal sensible loss

  27. Caloric (energy) maintenance • The daily fluid requirement is the same as the daily caloric requirement (e.g., if a child requires 1000 cc fluid, he also requires 1000 Kcalorie • In terms of fluids, calories most often provided as dextrose (glucose) • Difficult to provide total daily caloric requirement intravenously unless using TPN • Most often, it is sufficient to provide 20% of total daily caloric requirement intravenously so as to prevent ketosis

  28. Ongoing loses • Sensible: diuresis and diarrhea (rectal tube) • Insensible: feces, skin, respiration • 10ml/kg for each diarrhea • Burns- Parkland formula: BSA*4*mass for >20% of TBS of 2nd degree and > • Tachypnea: 5-10ml/kg/10resp> normal • Hyperthermia: 5-10 ml/kg/1°>38 • Vomiting:5-10 ml/kg/event

  29. Decreased maintenance • SIADH • Ventilated children • Inactive/hypothermic children

  30. Example of isotonic dehydration • 1y boy with moderate dehydration

  31. Water and sodium (Na) deficitssimple calculation: loss of 1 l of isotonic fluids • Water deficit: 10 kg × 10% = 1 L • Na deficit: 1 L × 140 mEq/L = 140 mEq

  32. Emergent fluid repletion with NS or D5% NS20 mL/kg × 10 kg = 200 mL (200 mL water and ≈30 mEq sodium)

  33. Ongoing repletion and maintenance requirementsRemaining water deficit: 1,000 mL - 200 mL = 800 mLDaily maintenance water requirement: 100 mL/kg/day × 10 kg = 1,000 mL/day800 mL + 1,000 mL = 1,800 mL/24 h = 75 mL/hRemaining Na deficit: 140 mEq - 30 mEq = 110 mEqMaintenance sodium requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day110 mEq + 30 mEq = 140 mEq/24 h140 mEq/1,800 mL ≈ 0.45% sodium chloride (½ NS)

  34. Maintenance potassium requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day30 mEq/1,800 mL ≈15–20 mEq/LIntravenous fluid based upon deficit calculations:D5% 1/2 NS with 20 mEq/L KCl at 75 mL/h

  35. Ongoing lossesExtrarenal losses should be replaced mL-for-mL if volumes are significant.The sodium content of the fluid lost should be estimated or measured in order to select the appropriate replacement fluid.

  36. Hyponatremic (125) dehydration example Water and sodium deficitsWater deficit: 10 kg × 10% = 1 LSodium deficit: [TBW(n) × 140 mEq/L] - [TBW(c) × 125 mEq/L]TBW(n) = 10 kg × 0.65 = 6.5 LTBW(c) = TBW(n) - water deficit = 6.5 L - 1 L = 5.5 LSodium deficit: (6.5 L × 140 mEq/L) - (5.5 L × 125 mEq/L) ≈ 220 mEq

  37. Emergent fluid repletion with NS or D5%NS20 mL/kg × 10 kg = 200 mL (200 mL water and ≈30 mEq sodium)

  38. Ongoing repletion and maintenance requirements Remaining water deficit: 1,000 mL - 200 mL = 800 mLDaily maintenance water requirement: 100 mL/kg/day × 10 kg = 1,000 mL/day800 mL + 1,000 mL = 1,800 mL/24 h = 75 mL/hRemaining Na deficit: 220 mEq - 30 mEq = 190 mEqMaintenance Na requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day190 mEq + 30 mEq = 220 mEq220 mEq/1,800 mL ≈120 mEq/L

  39. Maintenance potassium requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day30 mEq/1,800 mL ≈15–20 mEq/L KClIntravenous fluid based upon deficit calculations:D5% with 120 mEq/L Nacl and 20 mEq/L KCl at 75 mL/h D5%NS with added potassium could be provided for the initial half of the total volume and completed with D5%1/2 NS with added potassium

  40. Hypernatremic dehydration example Total Fluids loss= free water losses+ isotonic fluids losses FreeH2O deficit = TBW(c) × [(serum Na/140) - 1] Total fluid deficit- free water deficit= isotonic losses

  41. Water and sodium deficitsTotal water deficit: 10 kg × 10% = 1 LTBW(c) = TBW(n) - 1L = (10 kg × 65%) - 1 L = 5.5LFree water deficit: TBW(c)[(155/140) - 1] = 5.5[(155/140) - 1] = 0.59 LIsotonic deficit = total water deficit - free water deficit = 0.41 LSodium deficit: 0.41 L × 140 mEq/L ≈ 60 mEq

  42. Emergent fluid repletion with NS or D5%NS20 mL/kg × 10 kg = 200 mL (200 mL water and ~30 mEq sodium)

  43. Ongoing repletion and maintenance requirementsRemaining total water deficit: 1,000 mL - 200 mL = 800 mL, plan to replace over 36–48 h or 400 mL/day × 2 daysDaily maintenance water requirement: 100 mL/kg/day × 10 kg = 1,000 mL/day1,000 mL + 400 mL = 1,400/24 h or ≈60 mL/hRemaining sodium deficit: 60 mEq - 30 mEq = 30 mEqMaintenance sodium requirement: 3 mEq/100 mL of water intake × 1,000 mL/day = 30 mEq/dayTotal sodium requirement: 30 mEq + 30 mEq = 60 mEq60 mEq/1,400 mL or ≈0.225% sodium chloride

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