New Trends in the Utilization of Intravenous Fluids

Abstract

Intravenous fluids (IVFs) are the most commonly used drugs in hospitalized patients. Knowledge of the indications and pharmacokinetics of IVFs is critical for all medical disciplines. Isotonic saline (normal saline, 0.9% NS) is the most utilized intravenous solution. Isotonic saline effectively expands the intravascular compartment, as one-quarter of the infusate goes intravascularly, while the remaining three-quarters go into the interstitial space. The proper use of IVFs in different clinical scenarios is paramount. IVFs differ with regard to their half-life, intravascular volume expansion, preparation, and cost. Crystalloids are more commonly utilized due to their relatively low cost and availability. Colloids are very advantageous in cases of shock or hemorrhage, as they remain in the intravascular space, thus facilitating an increase in blood pressure (BP) prior to blood administration. Colloids are also advantageous in cases of burns and severe hypoglobulinemia. Human albumin (5%, 20%, and 25%) is the most used colloid solution. It remains intravascularly provided and there is no capillary leak as in systematic inflammation. The goal in hospitalized patients is timely and adequate intravenous fluid resuscitation. Utilization of a large volume of isotonic saline may lead to hypervolemia, hypernatremia, hyperchloremia, metabolic acidosis, and hypokalemia. The use of balanced intravenous solutions has been advocated to avoid these complications.

Keywords: albumin; balanced solutions; colloid solutions; crystalloid solutions; fluid resuscitation; hydroxyethyl starch; intravenous fluids; isotonic saline; lactated ringer; plasma-lyte.

Figure 1. Comparison of the distribution of 1 L of common IVFs in a lean 80 kg man, assuming no capillary leak.

IVF: intravenous fluid; D5W: 5% dextrose in water; NS: normal saline; LR: Ringer's lactate; ICF: intracellular fluid.