Concerns raised about saline in intravenous fluid

By Dr. Ananya Mandal, MDFeb 27 2018

A new set of studies has explored the saline used in intravenous fluids in hospitals and found that they may not be as safe as earlier believed. These two large studies have found that the presently used concentration of saline leads to an increased risk of kidney damage and death and replacing them with an alternate fluid could reduce the deaths by 50,000 to 70,000 and reduce the number of kidney failures by 100,000 annually in the United States.

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The studies were presented at the Society of Critical Care Medicine (SCCM) annual meeting this week. The studies were published in the latest issue of the journal New England Journal of Medicine.

Researchers explain that saline IV fluids are one of the most commonly used medications in healthcare to prevent dehydration, flush wounds, deliver IV medications, maintain dialysis and chemotherapy and maintain the blood pressure of the patients. These fluids are used in patients who cannot feed on their own and need essential nutrients. Saline IV fluids have been in use for over a century in the US. New evidence shows that saline or salt water at regulated osmolarity or concentration can cause damage to the kidneys especially when they are used in large amounts. Other fluids are saline along with other electrolytes such as potassium which are used in Europe and Australia.

The studies included over 28000 patients admitted at Vanderbilt University. They were given either plain saline or the balanced IV fluid. They noted that for every 100 patients who received the balanced fluid, there was one less death or kidney damage proving that it was safer than plain saline. Wesley Self, MD, an associate professor of medicine at Vanderbilt University School of Medicine in Nashville explained that these saline fluids contain very high levels of sodium and chloride which are far more than what is present in blood. This may be the reason for the harm they cause he said.

For this study, Vanderbilt used saline and balanced fluids alternatively for a month each for a year in the emergency room and in the intensive care units at their set up. On every even numbered month they used saline and odd numbered months they used the balanced fluids such as Ringer’s lactate or Plasma-Lyte-A. These balanced fluids have less sodium than saline. All patients were followed up for 30 days to see how they did. Deaths and kidney damage was much less among those who received balanced fluids than saline. For example 7942 patients received balanced fluids and of these 1139 developed complications. On the other hand 7860 patients received saline and of these 1211 patients developed complications. The difference was of 1.1 percent. According to Self, this difference becomes large when millions and millions of patients are considered.

Study author Dr. Matthew Semler said that around 30 million hospitalizations are seen yearly in the US and use of this balanced fluid instead of saline can prevent tens or hundreds of thousands of deaths and kidney damage. Seeing the results of these studies, Vanderbilt hospital has now switched to balanced fluids from plain saline. Both types of fluids are similar in terms of costs and most manufacturers make both types. This means that the switch is inexpensive and easy. Two more similar studies in large populations are underway from Brazil and Australia that could provide deeper insights into this matter.