Liver Disease (see End-Stage Liver Disease, [[End-Stage Liver Disease]]): impaired hepatic metabolism will impair lactate conversion
Metabolic Alkalosis (see Metabolic Alkalosis, [[Metabolic Alkalosis]]): lactated ringers may worsen pre-existing metabolic alkalosis
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)
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 (see Half Normal Saline, [[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%
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 Lactated Ringers
“Balanced” Crystalloid Solution: isotonic with blood
Contains 130 mEq of Sodium per liter (130 mmol/L)
Contains 109 mEq of Chloride per liter (109 mmol/L)
Contains 28 mEq of Lactate per liter (28 mmol/L)
Lactate is normally converted to pyruvate by lactate dehydrogenase in the liver (via the Cori cycle) -> pyruvate (the first designated substrate of the gluconeogenesis pathway) is subsequently converted to glucose, a process which generates bicarbonate
Contains 4 mEq of Potassium per liter (4 mmol/L)
Contains 3 mEq of Calcium per liter (1.5 mmol/L)
Similar in composition to Hartmann’s solution (which is more commonly found in British and Irish hospitals)
Administration
IVF Resuscitation: 20 to 30 ml/kg body weight/hr
Lactated Ringers is generally considered unsuitable for maintenance fluid therapy, as the sodium content is too low (especially for children)
Hypercalcemia (see Hypercalcemia, [[Hypercalcemia]])
Hyperkalemia (see Hyperkalemia, [[Hyperkalemia]]): usually only occurs in the setting of renal failure and high-volume lactated ringers infusion (due to the relatively small amount of potassium per liter)
