Perioperative Fluid Management and Clinical Outcomes in Adults

2006 Survey of Anesthesiology  
The administration of IV fluid to avoid dehydration, maintain an effective circulating volume, and prevent inadequate tissue perfusion should be considered, along with the maintenance of sleep, pain relief, and muscular relaxation, a core element of the perioperative practice of anesthesia. Knowledge of the effects of different fluids has increased in recent years, and the choice of fluid type in a variety of clinical situations can now be rationally guided by an understanding of the
more » ... ical and biological properties of the various crystalloid and colloid solutions available. However, there are few useful clinical outcome data to guide this decision. Deciding how much fluid to give has historically been more controversial than choosing which fluid to use. A number of clinical studies support the notion that an approach based on administering fluids to achieve maximal left ventricular stroke volume (while avoiding excess fluid administration and consequent impairment of left ventricular performance) may improve outcomes. In this article, we review the available fluid types and strategies of fluid administration and discuss their relationship to clinical outcomes in adults. A vailable IV fluids vary in their biological and physicochemical properties. Choice of fluid in clinical practice should be guided by an understanding of these differences. Hemorrheology, hemostasis, vascular integrity, inflammatory cell function, and the magnitude and duration of intravascular volume expansion are influenced to varying degrees by the different fluids. There are extensive clinical data describing the effects of different solutions on these variables. However, only very limited large-scale studies have been conducted to distinguish between the effects of the different classes of fluid on patient outcomes, and the available data are inconclusive. Many of the effects of different fluid solutions are governed by their distribution within the physiological compartments of the body. The following model, although simplistic, is conceptually useful. Fluid Compartment Physiology Total body water for a 75-kg individual is approximately 45 L (60%). Two-thirds of this (30 L) is intracellular water. The remaining third (15 L) in the extracellular compartment is divided between the intravascular (3 L) and extravascular (12 L) compartments (Fig. 1) . The total intravascular volume (or blood volume) is approximately 5 L and has intracellular (red and white cells and platelets: 40% [2 L]) and extracellular (plasma: 60% [3 L]) components. Plasma is a solution in water of inorganic ions (predominantly sodium chloride), simple molecules such as urea, and larger organic molecules such as albumin and the globulins. The cell wall separates the intracellular compartment from the extracellular compartment. The capillary endothelium and the walls of arteries and veins divide the extracellular compartment into the intravascular and the interstitial (tissue or extravascular) compartments. Water moves freely through cell and vessel walls and is distributed throughout all these compartments. The energy-dependent Na ϩ /K ϩ adenosine triphosphatase in cell walls extrudes Na ϩ and Cl Ϫ and maintains a sodium gradient across the cell membrane: Na ϩ is an extracellular ion. The capillary endothelium is freely permeable to small ions such as
doi:10.1097/01.sa.0000220743.22416.75 fatcat:jmzjtsfkbfcohnoghe7watl6ga