The choice of IV fluids in hospital settings

Simon Oczkowski, MD, MHSc, MSc, is a critical care clinician and an associate professor of medicine in the Division of Critical Care at McMaster University. His clinical and research interests include end-of-life care and decision-making, organ donation, and patient and family engagement. He has developed guidelines for the Society of Critical Care Medicine and European Society of Intensive Care Medicine.

How do you decide which IV fluid to use in hospitalized patients requiring IV fluid resuscitation?

Simon Oczkowski, MD, MHSc, MSc: In hospitalized patients, either those who are in the emergency department—or are being cared for by an internist in the emergency department—or those on the ward in the intensive care unit (ICU), fluids can basically be divided into 2 major categories, and they vary from country to country or region to region. The most common fluids are going to be normal saline—0.9% normal saline—or balanced crystalloids. The most common of these around the world is Ringer lactate; however, there are other formulations—there are commercial formulations as well, things like Plasmalyte—which are also balanced solutions. The difference between these 2 is that normal saline has equimolar equivalence of sodium and chloride ions and tends to be more acidic, whereas your balanced solutions tend to have a greater variation of components and tend to be more pH neutral.

Over the past 10 to 20 years, there have been a number of clinical trials comparing these 2 types of crystalloids: normal saline versus balanced solutions. The differences between them appear to be small, insofar as the trials that we now have [are concerned], including the SALT-ED trial, the SMART trial—these include many thousands of patients and there’ve been many meta-analyses done, including large trials like that—but also the studies done over the preceding years. What we’ve found is that balanced crystalloid solutions may be associated with reduced mortality; however, any difference in that area is small. In critically ill patients, they may result in less kidney injury and perhaps a lower risk of needing dialysis or renal replacement therapy. So, this is a field where—you know, almost every acute patient needs IV fluids—and as of now, we don’t know for sure—balanced crystalloid solutions such as Ringer lactate are likely the preferred ones to be used. The cost is similar, and they may actually improve clinical outcomes. And that is why for almost all hospitalized patients Ringer lactate or a balanced crystalloid solution would be the first choice.