(2) Five hundred ml of 6 percent hetastarch (trade name Hextend) weighs
1.3 pounds and will expand the intravascular volume by 800 ml within one hour. One
500 ml bag of Hextend solution is functionally equivalent to three 1,000 ml bags of
lactated Ringer's. There is more than a 51/2 pound advantage in the overall weight-to-
benefit ratio (1.3 lbs to 7.2 lbs, respectively). The expansion using Hextend is
sustained for at least eight hours. For these reasons, Hextend is the fluid of choice.
See figure 1-4 for an illustration of an IV bag of Hextend.
Figure 1-4. Hextend.
(3) The first consideration in selecting a resuscitation fluid is whether to use
a crystalloid or colloid solution. Crystalloids are fluids such as Ringer's lactate or normal
saline where sodium is the primary osmotically-active solute. Since sodium eventually
distributes throughout the entire extracellular space, most of the fluids in crystalloid
solutions remain in the intravascular space for only a limited time. Colloids such as
Hextend are solutions where the primary osmotically active molecules are of greater
molecular weight and do not readily pass through the capillary walls into the interstitial
space. These solutions are retained in the intravascular space for a much longer period
than crystalloids. In addition, the oncotic pressure of colloid solutions may result in an
expansion of the blood volume that is greater than the amount infused.