Switching from saline in IVs could save tens of thousands

Using an alternative to the standard saline solution used in most IV bags could reduce risks of kidney damage and even death, two new studies found.

Vanderbilt University conducted the research and has begun phasing the fluid out of its emergency department after finding that the alternative fluid worked just as well as saline and reduced kidney risks. 

The difference could mean 50,000 to 70,000 fewer deaths and 100,000 fewer cases of kidney failure each year in the US, researchers estimate.

Some doctors are hoping the results will persuade more hospitals to switch. 

‘We’ve been sounding the alarm for 20 years’ about possible harms from saline, said Dr John Kellum, a critical care specialist at the University of Pittsburgh. ‘It’s purely inertia’ that prevents a change, he said.

Kellum had no role in the studies, which were discussed Tuesday at a critical care conference in San Antonio and published by the New England Journal of Medicine.

IVs are one of the most common things in health care. They are used to prevent dehydration, maintain blood pressure or give patients medicines or nutrients if they can’t eat.

Saline – salt dissolved in water – has been the most widely used fluid in the US for more than a century even as evidence has emerged that it can harm kidneys, especially when used a lot.

Other IV solutions called balanced crystalloid fluids include saline but also contain potassium and other things that make them more like plasma, the clear part of blood. They’re widely used in Europe and Australia.

Oddly, there is no clear reason that saline has become the historically favoured IV fluid.

The two forms have both been around for more than 100 years, their costs are comparable – and, a dollar or two per bag, negligible – and they are used interchangeably.

‘There’s no evidence or rationale, it’s just kind of the way things were,’ says Dr Matthew Semler, a Vanderbilt University doctor who led the new studies.

‘It’s kind of an industry joke that what [specialty] you trained in determined what you use,’ says Dr Semler.

Saline ‘is one of those things that we do so commonly that we don’t even think to examine it,’ he says. ‘It got grandfathered in before we were so focused on evidence-based medicine.’

But in recent years, more researchers, including Dr Kellum and Dr Semler, have taken a fresh look at saline’s real effects.

Dr Semler’s two studies involved 28,000 patients at Vanderbilt University who were given IVs of saline or a balanced fluid. For every 100 people on balanced fluids, there was one fewer death or severe kidney problem.

Since there are about 30 million people hospitalized in the U.S. alone each year, ‘there are tens or hundreds of thousands of patients who would be spared death or severe kidney problems by using balanced fluids instead of saline,’ says Dr Semler.

Scientists do not yet know all the potential physical problems saline could be linked to, but Dr Kellum’s research has explored at least one.

Saline contains salt, which is composed of sodium and chloride. But its chloride content is actually higher than that of human blood.

Research has suggested that chloride might cause blood vessels to constrict, limiting blood flow to the kidneys. Other studies, like Dr Kellum’s, have posited that the overall chlorine may stoke inflammation in general.

Either of these would affect a broad set of organs, but kidneys feel it worst, and first and can quickly deteriorate with devastating effects for the rest of the body.

The kidneys act as the body’s sewage system, removing waste from the blood stream. They also regulate red blood cell production, fluid balances and blood pressure.

So as the kidneys take a turn for the worse, they quickly begin to drag overall health down with them.

‘Kidney failure is associated with a significantly higher risk of death,’ says Dr Semler.

A commonly cited estimate, he says is that ‘if a patient who has a severe infection in the ICU develops a kidney injury, about half will not survive their hospital stay.’

Kidneys are complicated, and so are the possible causes for their damage and potential failures. 

Kidney damage can be caused by infection, and by the antibiotics that treat infections. The organs regulate blood pressure, but can be damaged by low blood pressure. Even the contrast dye used in CT scans can be harmful to the kidneys.

Overall, ‘there is a very high risk of kidney injury, and multiple exposures’ – like repeatedly administered saline – ‘add to that risk, and that’s why we think eliminating at least one of those exposures could be helpful,’ Dr Semler says.

After seeing the results two months ago, Vanderbilt hospital officials decided to primarily use balanced fluids. The University of Pittsburgh also has largely switched to them, Kellum said.

IV fluids have been in the news since Hurricane Maria hit Puerto Rico last fall, shutting down electricity to three plants owned by Baxter International, one of the biggest makers of these fluids. The shortage has eased, but some supply issues remain.

It is unclear if balanced crystalloid fluids suffered the same shortages, but since the same companies already make and sell it to hospitals and health providers, there is not likely to be a significant barrier to the switch.

‘The lesson out of this is that there’s been a lot of attention on advancing new drugs – which are expensive and promising – and we have been slow to turn or attention to daily practice,’ Dr Semler says.

‘Understanding the best care for common medical treatments can be as exciting as new drugs, so we need to make sure that with the things we’re doing commonly, we know exactly what we’re doing and have good evidence for them,’ he adds.