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ivfluids

intravenous (iv) fluids

introduction

  • ideally a iv crystalloid would be close to physiologic and minimise incompatibilities with blood transfusions and other medications, these means:
    • no calcium
    • an osmolarity close to blood of 285mOsm/L
    • K of around 4mM to reduce risk of either hypokalaemia or hyperkalaemia
    • Na of 136mM
    • Cl 109mM
    • lactate 28-34
    • Mg 1.5mM as most hospitalised patients have low Mg
  • to avoid incompatibilities, most of us still use the less than ideal 0.9% saline

common crystalloids

0.9% "normal" saline

  • perhaps the least physiologic of the common crystalloids but it is the default iv fluid for many despite theoretic disadvantages of:
    • acidotic
      • thus may increase hyperkalaemia due to transcellular shifts
      • large volumes rapid infusion of NS can cause hyperchloraemic metabolic acidosis
    • hyperchloraemic, which theoretically risks renal impairment
    • slightly hypertonic at 286 mOSM/L
  • Na 154mM, Cl 154mM and thus not “normal” at all when compared to blood as 0.6% saline is closer to blood levels of NaCl
  • “saline” solutions were first used IV in the 1830's to Rx cholera in Europe

Hartmann's solution

  • similar to Lactated Ringer's solution
  • slightly hypotonic with osmolarity of 274 mOsm/L
  • Na 131mM, K 5mM, Cl 111mM, lactate 29mM, calcium 2mM, pH 6.5
  • although its pH is 6.5, it is an alkalizing solution as lactate is metabolised to bicarbonate
  • the calcium limits its compatibility with other iv agents including blood transfusions
  • the slightly higher K concentration may not be as good as LR in patients at risk of hyperkalaemia

Lactated Ringer's (LR) solution

  • Sydney Ringer developed his Ringer's solution in the 1880's as a fluid which maintained contractility of a frog heart muscle tissue, but not widely used in medicine until decades later
  • Na 130mM, K 4mM, Cl 109mM, lactate 28mM, Ca 1.5mM
  • slightly hypotonic with osmolarity of 273 mOsm/L
  • although its pH is 6.5, it is an alkalizing solution as lactate is metabolised to bicarbonate
  • the calcium limits its compatibility with other iv agents including blood transfusions

4% dextrose with 0.18% saline (4%D + N/5S)

  • a commonly used maintenance fluid, often with KCl added

other fluids

12.5% dextrose

  • to make 500mL:
    • inject 35mL of 50% D into the 500mL bag of 10% D

12.5% dextrose with 0.9% saline

  • to make 500mL:
    • withdraw 70ML from the 500mL bag of 10% D and inject 35mL of 50% D and 23mL 20% saline

10% Dextrose with 0.9% NaCl

  • to make up 500mL:
    • inject 25mls of NaCl 20% into the 500ml bag of 10% D
  • to make up 1000mL:
    • inject 49ml of NaCl 20% into the 1000ml bag of 10% D

5% Dextrose with 0.9% saline:

  • to make up 500mL:
    • inject 25mL 0.9% saline into the 500mL bag of 5% D
ivfluids.txt · Last modified: 2016/07/05 07:43 by 127.0.0.1

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