Editing IV fluids (section)

== Crystalloids ==

* Electrolyte solutions with small molecules that can diffuse freely from intravascular to interstitial fluid compartments
* 25% will stay intravascularly, and 75% will be in the interstitial compartment
* 0.9% saline
** Differs from plasma - higher sodium and chloride concentrations, higher osmolality, lower pH
** Cause interstitial oedema more than CSL due to higher sodium load
** Produces a hyperchloraemic metabolic acidosis in large volumes
* Ringer's lactate (CSL/Hartmann's)
** Essentially 0.9% NaCL with sodium lactate, potassium and ionised calcium added
** Doesn't change pH
** Doesn't change serum lactate in healthy patients, and the impact on unwell patients is unknown, but is thought to be negligible, unless the bloods are taken from downstream
* 5% dextrose
** Does provide some calories - 3L = 510kcal/day, although this is less important now that we have TPN and enteral feeding
** Causes a disproportionate cellular swelling due to uptake of dextrose; conversely, causes cellular dehydration in patients with impaired cellular glucose uptake
** Encourages anaerobic metabolism in critically unwell patients - causes a significant rise in serum lactate
** Causes hyperglycaemia
** Therefore, don't use it for critically ill patients