Objective: Intravenous fluids are broadly categorized into colloids and crystalloids. The aim of this review is to present under a clinical point of view the characteristics of intravenous fluids that make them more or less appropriate either for maintaining hydration when enteral intake is contraindicated or for treating hypovolemia.
Methods: We considered randomized trials and meta-analyses as well as narrative reviews evaluating the effects of colloids or crystalloids in patients with hypovolemia or as maintenance fluids published in the PubMed and Cochrane databases.
Results: Clinical studies have not shown a greater clinical benefit of albumin solutions compared with crystalloid solutions. Furthermore, albumin and colloid solutions may impair renal function, while there is no evidence that the administration of colloids reduces the risk of death compared with resuscitation with crystalloids in patients with trauma, burns or following surgery. Among crystalloids, normal saline is associated with the development of hyperchloremia-induced impairment of kidney function and metabolic acidosis. On the other hand, the other commonly used crystalloid solution, the Ringer's Lactate, has certain indications and contraindications. These matters, along with the basic principles of the administration of potassium chloride and bicarbonate, are meticulously discussed in the review.
Conclusions: Intravenous fluids should be dealt with as drugs, as they have specific clinical indications, contraindications and adverse effects.
Keywords: Albumin; balanced solutions; bicarbonate; colloids; crystalloids; hyperchloremia; metabolic acidosis; mortality; potassium.