Numerous difficulties with current regimens of colloid fluid replacement in patients with shock have been described. The lack of availability of whole blood in the field, the requirements for typing and cross matching, the danger of transmitting numerous infectious agents (including hepatitis B and hepatitis C viruses, and HIV), reduced concentrations of coagulation factors, and the absence of functioning platelets all complicate the use of whole blood for adequate resuscitation of hemorrhage. The limitations of liquid plasma for resuscitation from shock in the field include the relatively short shelf life, cost (currently $126/200 milliliters of plasma), and the risk of transmitting infectious agents. Although detergent treatment of plasma has been shown to reduce the risk of transmission of lipid-encapsulated viruses such as HIV, the persistent problem of possible contamination of large plasma pools with other infectious agents, for example, nonenveloped viruses, and requirements for storage in a frozen state have dampened enthusiasm for this approach to field resuscitation from hemorrhage (Klein et al., 1998). Finally, numerous studies have confirmed shock-mediated alterations in endothelial cell barrier integrity (Maier and Bolger, 1996).
Administration of albumin-containing solutions in the presence of a persistent capillary leak has been proposed to increase interstitial protein concentrations, promoting the movement of fluid from the intravascular compartment to the interstitium and aggravating hemorrhage-induced hypotension. These factors have resulted in an increased interest in synthetic colloids, agents that can be successfully retained in the intravascular compartment to increase circulating plasma volume. With these synthetic agents (the dextrans, hydroxyethyl starch [HES], and several gelatin preparations), the rare occurrence of anaphylactic reactions, mild inhibition of normal hemostasis, and the long-term retention of these agents within the body have tempered enthusiasm for their clinical use (Adelson et al., 1955; Bergqvist, 1982; Cronberg et al., 1966; Dahn et al., 1979; Leibold et al., 1983; Lucas et al., 1980; Macintyre et al., 1985; Metildi et al., 1984; Mishler, 1982; Stump et al., 1983). However, these agents are cheap to manufacture, are stable with storage at room temperature, and eliminate the infectious risks associated with blood products. Recent studies have shown that artificial colloids increased the levels of expression of adhesion molecules, increased the levels of synthesis of several proinflammatory cytokines, and promoted cellular apoptosis (Coimbra et al., 1996; Junger et al., 1997a,b, Rhee, 1998). Newer colloids that carry oxygen and that can be formulated for a variety of oncotic activities have considerable promise, but considerable research is required before their clinical application as resuscitation fluids.
Glucose-containing solutions have been avoided for resuscitation from hemorrhagic shock in patients with head trauma. The stress-related rise in circulating epinephrine levels decreases the level of insulin released by the pancreas, complicating metabolism of the glucose load. Furthermore, increased glucose levels have been shown to alter potassium-adenosine triphosphate (K-ATP) channels, thus excerbating shock-related ion redistribution across mem-