Intravenous Fluids

Intravenous fluids can be classified into:

  • Crystalloids
    Can pass freely through a semipermeable membrane. Can be further classified into:
    • ECF replacement solutions
      Have a [Na+] similar to ECF, such that they are confined mostly to the ECF.
    • Maintenance solutions
      Designed to distribute throughout TBW.
    • Special solutions
      These solutions don't fit into the above two categories, and include:
      • Hypertonic saline
      • Mannitol
      • 8.4% Sodium Bicarbonate
  • Colloids
    Substance evenly dispersed throughout another solution in which it is insoluble. Can be classified into:
    • Naturally occurring
      • Albumin
        Heat-treated human albumin.
        • Produced at low pH but not technically sterile
          Use within 3 hours of opening.
        • Contributes to plasma oncotic pressure
        • Contributes to drug and endogenous substance binding
    • Synthetic
      • Dextrans
        High molecular weight sugars synthesised from sucrose by bacteria.
        • Interfere with haemostasis due to vWF inhibition
        • Interfere with blood crossmatch
        • Risk of anaphylaxis
      • Gelatins
        High molecular weight proteins produced by collagen hydrolysis.
        • Greatest anaphylaxis risk
        • Do not interfere with clotting
      • Hydroxyl-ethyl starches
        • Risk of anaphylaxis
        • Risk of renal impairment
        • Accumulate in the reticuloendothelial system

Comparison of Crystalloids

Contents (mmol.L-1) 0.9% NaCl Hartmann's Plasmalyte
Na+ 154 130 140
Cl- 154 109 98
K+ 4 5
Ca2+ 3
Mg2+ 1.5
Lactate 28
Acetate 27
Gluconate 23
pH 5.0 6.5 5.5


Last updated 2020-10-09

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