Balanced IV Fluids Seem to be Safer than Saline in ICU

This article first appeared February 27, 2018 on MedPage Today.

Salynn Boyles, Contributing Writer

SAN ANTONIO — Hospitalized patients given IV balanced fluids instead of saline showed a roughly 1% decreased incidence of death and serious kidney injury, according to results of two studies that compared outcomes with the two widely used IV trauma therapies.

The improved outcomes, seen in both critically ill and non-critically ill patients, suggest that largely replacing saline with balanced fluids in the hospital setting could result in significant mortality and morbidity reductions, said Matthew W. Semler, MD, of Vanderbilt University Medical Center in Nashville, in a presentation at the Society of Critical Care Medicine (SCCM) annual meeting. The results were simultaneously published in the New England Journal of Medicine.

He told MedPage Today that while a 1% reduction may not sound large, the absolute impact would be highly significant given that more than 5 million people in the U.S. are treated in ICUs every year. Semler estimated that 50,000 to 75,000 deaths per year could be avoided by replacing saline with balanced fluids, along with 100,000 cases of renal failure leading to 40,000 to 50,000 patients needing dialysis.

“There has not been evidence in favor of saline or balanced fluids,” Semler said. “The choice about which one to use mostly comes down to how physicians are trained. Internal medicine physicians tend to use saline while anesthesiologists and surgeons tend to use balanced fluids more.”

He said that while historically 0.9% sodium chloride has been the most widely used intravenous fluid, crystalloid solutions with electrolyte composition closer to that of plasma, such as lactated Ringer’s solution or Plasma-Lyte A, are also widely used.

Critical care specialist Timothy Buchman, MD, of Emory Healthcare in Atlanta, who was not involved with the study, told MedPage Today that he believes the findings should be considered practice-changing.

Buchman said the historical rationale for giving 0.9% saline was that it was compatible with blood transfusions. “But we have reduced the need for blood dramatically in so many (hospital) situations,” he said.

The chloride concentration of saline is higher than that of human plasma. Balanced fluids, by contrast, are basically plasma electrolytes with some water.

“After roughly 75 years of intravenous medicine and 50 years of advanced trauma life support, we are finally recognizing that maybe what we should be giving is what the patient has been losing,” Buchman said.

Semler ‘s group randomized 15,802 adult patients being treated in ICUs at Vanderbilt University Medical Center to receive saline or a balanced crystalloid solution (lactated Ringer’s solution or Plasma-Lyte A) in one of the studies.

The primary outcome was major adverse kidney event within 30 days, which was a composite of death from any cause, new renal-replacement therapy, or persistent renal dysfunction before hospital discharge or within 30 days.

A total of 14.3% of the patients treated with a balanced crystalloid solution experienced a major adverse kidney event compared with 15.4% of patients given saline intravenous fluids (marginal odds ratio 0.91, 95% CI 0.84-0.99 and conditional OR 0.90, 95% CI 0.82-0.99, P=0.04).

In-hospital mortality at 30 days was 10.3% in the balanced-crystalloids group and 11.1% in the saline group (P=0.06) and the incidence of renal-replacement therapy was 2.5% and 2.9%, respectively (P=0.08) .

The incidence of persistent renal dysfunction was 6.4% and 6.6%, respectively (P=0.06).

In a second trial involving 13,347 non-critically ill hospitalized adults treated outside the ICU randomized to receive a balanced fluid or saline, the number of hospital-free days did not differ between the two groups.

But use of balanced crystalloids resulted in a lower incidence of major adverse kidney events within 30 days similar to that seen in the critically ill patients (4.7% versus 5.6%, adjusted OR 0.82, 95% CI 0.70-0.95, P=0.01).

“We saw a consistent signal in the critically ill and non-critically ill patients,” Semler said.

He said based on the strength of the findings, Vanderbilt hospitals are in the process of switching to balanced fluids both in the ICU and ward settings.

Pediatric critical care specialist Erin Stenson, MD, of Cincinnati Children’s Hospital, who was not involved with this study, said many clinicians at her institution have also switched from saline to primarily lactated Ringer’s for resuscitation based, in part, on findings from a study she presented at SCCM.

Among children with septic shock, hyperchloremia was associated with higher mortality and poorer outcomes in the study, according to Stenson’s group.

Although the researchers had no data on which type of IV solution the roughly 900 children in the study got, Stenson said the hypothesis was that saline IV use was significantly associated with hyperchloremia.

“Since the use of normal saline is the most prevalent fluid that has been given at our institution, we presume that this [hyperchloremia] was due to the use of normal saline,” she said.