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Crystalloid Isotonic Solution

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Crystalloid Isotonic Solution, Normal Saline, Lactated Ringers, Balanced Crystalloid, Isotonic Solutions

  • Types
  1. Lactated Ringers
  2. Normal Saline
  • Advantages
  1. Inexpensive and readily available
  2. Does not result in Allergic Reactions
  • Disadvantages
  1. Only transiently expand the intravascular volume
  2. Only 25% remains in intravascular space
  3. Requires infusion of 4-5x the deficit
    1. May result in pulmonary edema in critically ill
  • Preparations
  • Basic Saline
  1. Normal Saline (0.9% NaCl or NS)
    1. Osmolality: 308 mOsm/L
    2. Sodium: 154 mEq/L (with equivalent chloride)
    3. pH: 5-6
    4. Disadvantages
      1. Risk of hyperchloremic Non-Anion Gap Metabolic Acidosis (worse in renal dysfunction)
        1. However Normal Saline is an ideal solution in Vomiting (acid losses)
  • Preparations
  • Balanced Crystalloid (Buffered)
  1. Lactated Ringers (LR)
    1. Osmolality: 272 mOsm/L
    2. Sodium: 130 mEq/L
    3. Chloride: 109 mEq/L
    4. Lactate: 28 mEq/L (buffer)
    5. Also contains Potassium (4 mEq/L) and calcium (3 mEq/L)
    6. pH: 6.5
    7. First-line scenarios
      1. Large-volume crystalloid bolus or infusion (>2 Liters)
      2. Pancreatitis
      3. Pregnancy, especially hyperemesis (add dextrose to the solution)
    8. Disadvantages
      1. Hypotonic (avoid in Closed Head Injury due to Increased Intracranial Pressure risk)
      2. Drug Interactions (e.g. not campatible with Ceftriaxone)
      3. Lactate may accumulate in a preexisting Lactic Acidosis, and cannot initially be cleared
        1. LR contribution to serum lactate is negligible and should not persist Lactic Acidosis
  2. Plasma-Lyte 148 (or Normosol-R)
    1. Osmolality: 294 mOsm/L
    2. Sodium: 140 mEq/L
    3. Chloride: 98 mEq/L
    4. Buffer: 50 mEq/L (acetate and gluconate)
    5. Also contains Potassium (5 mEq/L) and Magnesium (3 mEq/L)
    6. pH: 7.4
  3. References
    1. Loflin (2015) Crit Dec Emerg Med 29(9): 11-18
  • Preparation
  • Other Isotonic Solutions
  1. D5W with 3 ampules Sodium Bicarbonate
    1. Isotonic alkalotic solution
    2. Indications
      1. Pre-existing non-Anion Gap, hyperchloremic Metabolic Acidosis or RTA
    3. References
      1. Weingart and Orman in Herbert (2015) EM:Rap 15(10): 16-7
  1. Background
    1. Primary Acid-Base Homeostasis is achieved via pulmonary and renal mechanisms
    2. Intravenous Fluid acidity only affects Blood pH with prolonged or large volume Intravenous Fluid administration
  2. Strong ions (Sodium and chloride) determine Intravenous Fluid acidity
  3. Normal serum cation-anion difference: 38 meq/L
    1. Positive serum Sodium Cations (140 meq/L) minus
    2. Negative Serum Chloride anions (102 meq/L)
  4. Intravenous Fluid impacts normal serum acidity when its cation-anion difference is not 24 meq/L
    1. Accounts for 14 meq/L difference resulting from dilution of the normally acidic Serum Albumin
    2. Overall neutral Intravenous Fluid: 38 meq/L (cations-anions) - 14 meq/L (albumin dilution) = 24 meq/L
  5. Intravenous Fluid cation-anion difference or gap will impact the serum acidity based on the serum bicarbonate level
    1. Cation-Anion difference of 15 meq/L has no impact on Blood pH when serum bicarbonate is also 15 meq/L
  6. Intravenous Fluid acidities (cation-Anion Gap)
    1. Lactated Ringers: 24 meq/L
      1. Neutral (no change on acidity) - balanced solution
    2. Normal Saline (or D51/2NS or D5W): 0 meq/L
      1. Acidic (will acidify the serum) - significantly if multiple liters infused
      2. Risk of hyperchloremic, Non-Anion Gap Metabolic Acidosis
      3. Risk of pro-inflammatory affects, Coagulopathy and increased infection risk
      4. Risk of decreased GFR and Acute Kidney Injury
    3. Plasmalyte: 55 meq/L
      1. Alkalotic
  7. Either NS or buffered solution (e.g. LR, Plasmalyte) are suitable for non-massive Fluid Replacement
    1. No increased Acute Kidney Injury or mortality with Normal Saline compared with buffered solution with non-massive replacement
    2. Young (2015) JAMA 314(16): 1701-10 +PMID:2644692 [PubMed]
  8. References
    1. Loflin (2015) Crit Dec Emerg Med 29(9): 11-18
    2. Weingart in Majoewsky (2013) EM:Rap 13(8): 6
  • References
  1. Weingart and Orman in Herbert (2015) EM:Rap 15(10): 16-7