Half Normal Saline

Indications

Intravenous (IV)


Pharmacology

Definitions

  • Crystalloids: sodium-based electrolyte solutions

History of Crystalloids

  • 1831 (Europe): first clinical use of crystalloids during the India Blue Cholera pandemic
  • 1896 (Holland): Hartog Hamburger (Dutch physiologist) invented “normal saline”: he intended to use this fluid in the in vitro study of erythrocyte lysis
  • 1880 (England): Sydney Ringer invented “Ringer’s solution”: he used this fluid to sustain contractility in isolated frog hearts
    • The fluid was inadvertently made with tap water (instead of distilled water) and the inadvertent presence of calcium likely led to the experiment being successful
    • Ringer analyzed the fluid and found that it contained calcium, sodium, potassium, chloride, and magnesium
  • 1930’s (USA): pediatrician Alexis Hartmann added lactate to a solution very similar to Ringer’s solution, creating a forerunner of “Lactated Ringer’s” (see Lactated Ringers, [[Lactated Ringers]]): lactate was added by Hartmann to “buffer” the solution (creating a “balanced” solution)

Balanced vs Unbalanced Crystalloids

  • Balanced Crystalloids: mildly hypotonic lactate or acetate buffered solutions (with signficantly lower chloride concentrations than saline)
    • Lactated Ringer’s (LR) (see Lactated Ringers, [[Lactated Ringers]])
    • Acetate Ringer’s
    • Hartmann Solution
    • Plasma-Lyte (from Baxter Healthcare)
  • Unbalanced Crystalloids : contain no buffer (note: additionally, normal saline has higher chloride concentration than the above)
    • Normal Saline (NS) (see Normal Saline, [[Normal Saline]]): 0.9% NaCl
    • Half Normal Saline: 0.45% NaCl
    • Quarter Normal Saline (see Quarter Normal Saline, [[Quarter Normal Saline]]): 0.22% NaCl
    • Dextrose 5% in Water (D5W) (see Dextrose 5% in Water, [[Dextrose 5% in Water]]): Dextrose 5%
    • D5 Normal Saline (D5NS): Dextrose 5% + 0.9% NaCl
    • D5 Half Normal Saline (D5 1/2NS): Dextrose 5% + 0.45% NaCl
    • D5 Quarter Normal Saline (D5 1/4NS): Dextrose 5% + 0.22% NaCl
  • Comparative Data
    • Use of balanced crystalloid is associated with decreased kidney pathology in rat model of hemorrhagic shock, as compared to unbalanced crystalloid [MEDLINE]
    • Chloride-restrictive IV fluid resuscitation strategy is associated with decreased renal injury [MEDLINE]: may be related to hyperchloremia’s induction of renal vasoconstriction

Composition of Various Intravenous Fluids

INTRAVENOUS FLUIDS


Adverse Effects

Cardiovascular Adverse Effects

Renal Adverse Effects

  • Hyperchloremic Non-Anion Gap Metabolic Acidosis [MEDLINE] (see Metabolic Acidosis-Normal Anion Gap, [[Metabolic Acidosis-Normal Anion Gap]])
    • Mechanism: likely involves narrowing of strong ion difference between sodium and chloride
  • Hyponatremia (see Hyponatremia, [[Hyponatremia]])

Other Adverse Effects

  • Exacerbation of Cirrhotic Ascites (see Ascites, [[Ascites]])

References

  • Rapid saline infusion produces hyperchloremic acidosis in patients undergoing gynecologic surgery. Anesthesiology. 1999 May;90(5):1265-70 [MEDLINE]
  • Association between a chloride-liberal vs chloride-restrictive intravenous fluid administration strategy and kidney injury in critically ill adults. JAMA. 2012 Oct 17;308(15):1566-72. doi: 10.1001/jama.2012.13356 [MEDLINE]
  • Balanced vs unbalanced crystalloid resuscitation in a near-fatal model of hemorrhagic shock and the effects on renal oxygenation, oxidative stress, and inflammation. Resuscitation. 2012 Jun;83(6):767-73. doi: 10.1016/j.resuscitation.2011.11.022. Epub 2011 Dec 4 [MEDLINE]
  • The ideal crystalloid – what is ‘balanced’? Curr Opin Crit Care. 2013 Aug;19(4):299-307. doi: 10.1097/MCC.0b013e3283632d46 [MEDLINE]
  • Crystalloids for Fluid Resuscitation in Sepsis: Where Is the Balance? Ann Intern Med. 2014 Jul 22. doi: 10.7326/M14-1565 [MEDLINE]