There are two main types of volume expanders: crystalloids and colloids. Crystalloids are
aqueous solutions of mineral salts or other water-soluble molecules. Colloids contain larger insoluble molecules, such as
gelatin;
blood itself is a colloid. There is no evidence that colloids are better than crystalloids in those who have had trauma, burns, or surgery. Colloids are more expensive than crystalloids. As such, colloids are not recommended for volume expansion in these settings.
Crystalloids The most commonly used crystalloid fluid is
normal saline, a solution of
sodium chloride at 0.9% concentration, which is close to the concentration in the blood (
isotonic). ''
Ringer's lactate or Ringer's acetate'' is another isotonic solution often used for large-volume fluid replacement. The choice of fluids may also depend on the chemical properties of the medications being given.
Normal saline Normal saline (NS) is the commonly used term for a solution of 0.9%
w/v of
NaCl, about 300
mOsm/L. Less commonly, this solution is referred to as
physiological saline or
isotonic saline, neither of which is technically accurate. NS is used frequently in
intravenous drips (IVs) for patients who cannot take fluids orally and have developed or are in danger of developing
dehydration or
hypovolemia. NS is typically the first fluid used when hypovolemia is severe enough to threaten the adequacy of blood circulation, and has long been believed to be the safest fluid to give quickly in large volumes. However, it is now known that rapid infusion of NS can cause
metabolic acidosis.
Ringer's solution Lactated Ringer's solution contains 28 mmol/L lactate, 4 mmol/L K+ and 1.5 mmol/L Ca2+. It is very similar – though not identical – to
Hartmann's solution, the ionic concentrations of which differ slightly. Ringer's lactate contains calcium, which may combine with citrate (that is used as a preservative in some blood products) and form a precipitate; therefore, it is not to be used as a diluent in blood transfusions.
1/3 NS 2/3D5 2/3 1/3 is no longer recommended as a maintenance intravenous fluid in children as it is hypotonic and isotonic fluids are preferred.
Glucose (dextrose) Intravenous sugar solutions, such as those containing
glucose (also called dextrose), have the advantage of providing some energy, and may thereby provide the entire or part of the energy component of
parenteral nutrition. Types of glucose/dextrose include: •
D5W (5% dextrose in water), which consists of 278 mmol/L dextrose •
D5NS (5% dextrose in normal saline), which, in addition, contains normal saline.
Plasma-lyte Plasma-Lyte A and
Plasma-Lyte 148 are buffered crystalloid solutions that may be infused intravenously, Therefore, they should theoretically preferentially increase the
intravascular volume, whereas crystalloids also increase the
interstitial volume and
intracellular volume. However, there is no evidence to support that this results in less mortality than crystalloids.
Gelofusine Gelofusine is a colloid volume expander which may be used as a
blood plasma replacement when a significant amount of blood is lost due to extreme
hemorrhagia, trauma, dehydration, or a similar event. It is an intravenous colloid that behaves much like blood filled with albumins. As a result, it causes an increase in blood volume, blood flow, cardiac output, and
oxygen transportation. ==References==