Crystalloids versus colloids for fluid resuscitation in critically ill patients: hemodynamic, immunological and hemocoagulative effects related to volume replacement

Administration of fluid resuscitation in critically ill patients thought to need volume replacement, is the treatment of various forms of shock (hemorrhagic, distributive, or cardiogenic). Shock is a state of inadequate perfusion, which does not sustain the physiologic needs of organ tissues. Many conditions, including blood loss but also including non-hemorrhagic states such as dehydration, sepsis, impaired autoregulation, obstruction, decreased myocardial function, and loss of autonomic tone, may produce shock or shock like states. One of the longest-running debates in clinical medicine is whether colloids or crystalloids are superior for treating critically ill patients. The debate has been ongoing over their appropriate use and about the basic safety of colloids since albumin was first used during World War II to treat burned soldiers at Pearl Harbor and re-emerged during the 1970s and 1980s as colloids consumed an ever-greater proportion of pharmacy budgets, and often without clear indications for their use1. There are three broad categories of resuscitation fluids such as crystalloids, synthetic colloids and albumin-containing solutions: their clinician use is widely variable, although treatment of hemorrhagic shock needs blood transfusions. Ideally the choice of any medical treatment is based on an analysis of the balance of risk and benefit, supported by results of large-scale trials ad reviews. Patients in intensive care units receive resuscitation fluids each day: data demonstrate widespread variation in the choice of type of fluid. With the exception of the SAFE studies, published trials do not provide adequate statistical power. We can’t conclude that synthetic colloids are safe or crystalloids are recommend in critically ill patients, because the data are insufficient. Other than in patients with traumatic brain injury, administration of albumin to critically ill patients produces similar outcomes to administration of saline. HES should be avoided in patients with severe sepsis: the safety of the more recently HES solutions should be tested. Large trials of synthetic colloids in both heterogeneous and selected patient populations are required.