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Role of Synthetic Colloids in Resuscitation

　　John Kellum, MD,[9] of the University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, discussed the role of synthetic colloids in resuscitation. Based on the available data, there appear to be no easily discernible differences between colloids and crystalloids, although methodologic limitations hinder the formation of a sound conclusion.[10] There are many types of colloids; human albumin and blood are considered to be 2 of them. When hetastarch (HES) was compared with albumin in trauma patients, cardiac index, oxygen consumption index, and oxygen delivery index significantly increased only in the HES-treated patients. In septic patients, the same parameters increased and remained higher than baseline only in the HES group (P < .01) compared with albumin.[11] No advantage of albumin over HES was found. Albumin received considerable criticism as a detrimental agent after a meta-analysis suggested that it causes excess mortality to critically ill patients.[12] Subsequent meta-analyses did not confirm this report.
　　A French study from Schortgen and coworkers[13] compared septic patients receiving hydroxyethylstarch or gelatin for resuscitation. The use of hydroxyethylstarch was found to be an independent risk factor for acute renal failure. Of note is the fact that hydroxyethylstarch is different from HES, which is used in the United States, in that it is composed of a smaller starch molecule. What is interesting is that most of the currently used colloids are diluted in normal saline, and there is old evidence that the chloride content of these solutions might be as responsible for the decreased renal flow and subsequent renal failure. Newer colloids with more balanced solutions have become available.
　　A recent review found no evidence that one colloid solution is more effective or more safe than any other.[14] However, bleeding is another consideration with the use of colloids. A large retrospective review found that intraoperative use of HES in cardiac surgery with cardiopulmonary bypass may increase bleeding and transfusion requirements. The newer colloids, containing 6% HES, balanced electrolytes, a lactate buffer, and a physiologic level of glucose, have a safer profile regarding bleeding.[15] Additionally, it does not produce the same degree of hyperchloremic metabolic acidosis as other nonbalanced starches. Dr. Kellum concluded that there are considerable differences among colloids, and the use of more physiologically balanced solutions may be associated with a decreased risk of bleeding, metabolic acidosis, and renal failure.