There have been many studies through the years comparing the pros and cons of using normal saline vs. balanced fluids (aka “balanced crystalloids” or “lactated ringers”) in IV bags. The studies mentioned in this article both come from Vanderbilt University Medical Center. They were presented at this past week’s annual conference of the Society for Critical Care Medicine, and simultaneously published in the current issue of the New England Journal of Medicine (NEJM).
Both studies found that balanced fluids were associated with a very small decrease in kidney damage and death when compared to normal saline.
This AP story was republished by many news organizations. It did a good job of discussing the costs, and included an expert not involved in the study. However, we think more information was needed about the studies themselves, and what they found specifically. For a different take, we recommend reading this CNN story.
This debate is not resolved. More studies should (and will) emerge. Many hospitals and clinics have already transitioned over to using balanced fluids only, but not all of them. The stakes are huge for medical suppliers, medical institutions, and patients. As more studies emerge, we highly recommend readers keep an eye out for industry involvement in the studies trying to clarify this important issue.
In comparing the costs of normal saline vs. balanced fluids, the article states “the fluids cost about the same — a dollar or two per IV — and many suppliers make both types, so switching should not be hard or expensive.”
This is sufficient for a satisfactory rating, but readers should be aware that even a difference of a few pennies per bag would have a significant impact at the institutional level, and a massive impact on the national level.
The article states:
For every 100 people on balanced fluids, there was one fewer death or severe kidney problem.
And not much else is said. Unfortunately, this is an oversimplification, combining the findings of two studies (one on critically ill patients, one on non-critically ill patients) into one result. CNN’s reporting was much more detailed:
Of nearly 16,000 critically ill patients, 10.3% of those given balanced crystalloids and 11.1% of those given saline died in the hospital within a month. Serious kidney events arose in 14.3% of the “balanced” group and 15.4% in the saline group.On the other hand, the study of more than 13,000 patients who were not critically ill found that there was no difference in how early surviving patients were discharged in the four weeks after they came to the emergency room. But the researchers did find a slightly lower incidence of serious kidney events: 4.7% for the “balanced” group versus 5.6% for those receiving saline. This means 111 saline patients would need to be treated with balanced crystalloids instead in order to prevent one adverse kidney event.
Also, regarding this statement in the AP story: “The difference could mean 50,000 to 70,000 fewer deaths and 100,000 fewer cases of kidney failure each year in the U.S.”
This should be edited to include the statement, “if the study is replicated across the country.”
Given that this study is all about safety, we think the story should have provided more detail on the known harms of saline vs balanced fluids. The AP story does mention the kidney disease risk with saline, but doesn’t explore why physicians might be leery to use balanced fluids. As CNN explained:
Doctors may still opt for saline if, for example, a patient has low concentrations of sodium or chloride, Rice said. Many of his colleagues who treat brain injuries are also wary of using lactated ringers over saline because of its potential impact on the pressure within the skull, he added.“They get very very worried about increased swelling,” Rice said. More research could uncover which types of patients are most sensitive to the effect of one fluid over another, he said.
Very little information on the studies is provided. Were these randomized, controlled trials? What were the key limitations to the data? What further research is needed? As CNN noted:
“Hager said he believes that other studies will spin off from this research, which was conducted at a single medical center. He also noted that the research was unblinded, meaning that doctors ‘knew they were giving one fluid versus another, and that may have an impact on other decisions that they make.'”
No disease mongering here, though the study could have done more to stress that the thousands of lives saved is only if the changes are replicated nationally.
The story quotes two sources: One not involved with the study, and one who’s a study leader.
It’s mentioned “federal grants helped pay for the work,” which is sufficient.
A discussion of other fluid replacement strategies is not germane given the subject of this study.
The article does well in including this important context:
IVs are one of the most common things in health care … saline — salt dissolved in water — has been the most widely used fluid in the U.S. for centuries … other IV solutions called balanced fluids include saline but also potassium and other things that make them more like plasma, the clear part of blood. They’re widely used in Europe and Australia.
The story refers to a 20-year effort to better understand which IV fluids are best to use, which is helpful context. We think the story could have better stressed that’s what’s novel here is the size of the studies–lots of patients were included. But, we’ll give this a satisfactory for at least providing context.
This article does not appear to rely solely upon a news release.