Why Vanderbilt Doctors Are Cutting Off Saline In Their IVs

For decades, emergency physicians and intensive care doctors instinctively have been reaching for saline when they order intravenous fluids for a patient. Now a pair of two-year studies conducted at Vanderbilt Medical Center finds a slight but meaningful benefit to an alternative fluid. So the hospital is making a wholesale change and encouraging other hospitals to follow suit.

“It was just customary — myself included, as an internal medicine physician — we’d always use saline, and I’d never really thought that much about it,” says Matthew Semler, lead author of a study published in the New England Journal of Medicine.

As part of Vanderbilt’s push for more practical research, Semler thought someone should scrutinize one of the most basic treatments in a hospital. He hypothesized that saline might have some negative effects on kidney function. After all, it’s basically just table salt and water. So he tracked patients who got saline and those who got balanced crystalloids — also known as balanced fluids — which are comparable in cost and availability but not widely used. The fluids have less chloride and are more like human plasma.

In two separate studies involving 15,000 ICU patients and 13,000 in the ER, the results showed fewer deaths and instances of kidney failure with the balanced fluids. The difference in both studies was just one percent, but Semler says he expected incremental results.

“If there were a 15 or 20 percent difference in an outcome, we would have noticed that decades ago,” he says. “The costs are similar, so any data that a patient outcome is improved — even if it’s only one percent — probably is reason to switch.”

With 4 million hospitalized patients receiving fluids annually nationwide, one in a hundred starts to add up, co-author and ER physician Wesley Self says in a statement.

The study’s authors estimate that more than 50,000 deaths could be avoided with the change and twice as many cases of renal failure. Even just at Vanderbilt, they estimate the switch almost exclusively to balanced fluids could save hundreds of lives a year.