Balance scale in an ICU, saline vs balanced crystalloids.

Is Saline the Best Choice? New Study Questions Fluid Therapy in Intensive Care

Mira Elwood in Health & Wellness December 2025 • 4 min read.

"A meta-analysis reveals that saline might not be the safest option for critically ill patients, prompting a rethink on balanced crystalloid solutions."

For decades, saline has been a staple for fluid resuscitation and maintenance in intensive care units (ICUs). However, like all medical treatments, its safety and effectiveness warrant ongoing scrutiny. Recent insights into fluid physiology and potential complications like hyperchloremia, metabolic acidosis, and acute kidney injury have stirred debate about its routine use.

Balanced crystalloid solutions, designed to more closely mimic the electrolyte composition of plasma, have emerged as a potential alternative. These solutions offer the theoretical benefit of reducing the risk of complications associated with high chloride levels, prompting many clinicians to consider them a safer option.

However, studies comparing saline to balanced solutions have yielded mixed results. While some suggest that balanced solutions reduce the risk of acute kidney injury, the need for renal replacement therapy, and blood transfusions, others have found no significant advantage. To clarify this uncertainty, a new meta-analysis has investigated the impact of saline versus balanced crystalloids on mortality in ICU patients.

Does Saline Increase Mortality Risk in the ICU?

Balance scale in an ICU, saline vs balanced crystalloids.

A comprehensive meta-analysis, featured in Revista Española de Anestesiología y Reanimación, sought to evaluate the effects of saline compared to balanced crystalloids on patient mortality within intensive care settings. This study pooled data from multiple clinical trials to provide a more robust understanding of the risks and benefits associated with each type of fluid.

Researchers conducted an extensive search of medical databases, including Medline, Embase, Cochrane Library, ISI Proceedings, and Web of Science, to identify relevant studies. They focused on randomized controlled trials and prospective studies that assessed mortality in adult ICU patients receiving either saline or balanced crystalloid solutions for resuscitation or maintenance. Key criteria included:

Adult patients (18 years or older) admitted to the ICU.
Intervention: Administration of crystalloid fluids (balanced or unbalanced) for maintenance or resuscitation.
Primary Outcome: All-cause mortality in the ICU or hospital, typically measured at 28 or 60 days.

The analysis included eight studies encompassing a total of 20,684 patients. The findings indicated a statistically significant association between saline administration and increased mortality in ICU patients compared to those treated with balanced crystalloid solutions. Specifically, the odds ratio (OR) for mortality was 1.0972 (95% CI: 1.0049-1.1979), suggesting a roughly 10% increase in the odds of death with saline use.

The Implications for Clinical Practice

This meta-analysis adds to a growing body of evidence suggesting that saline may not be the optimal fluid choice for critically ill patients. The findings underscore the importance of considering balanced crystalloid solutions as a potentially safer alternative, especially given their alignment with the body's natural electrolyte composition. As research evolves, healthcare providers should stay informed and critically evaluate their fluid therapy practices to ensure the best possible outcomes for their patients.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.redar.2018.06.007, Alternate LINK

Title: Metaanálisis De Los Efectos Del Suero Salino En La Mortalidad En Cuidados Intensivos

Subject: Anesthesiology and Pain Medicine

Journal: Revista Española de Anestesiología y Reanimación

Publisher: Elsevier BV

Authors: A. González-Castro, M. Ortiz-Lasa, J.C. Rodriguez-Borregan, P. Escudero-Acha, E. Chicote, B. Suberviola, C. Blanco, Y. Peñasco, A. Jiménez Alfonso, J. Llorca, T. Dierssen-Soto

Published: 2019-01-01

Everything You Need To Know

What exactly is saline, and why is there a discussion about its use in intensive care?

Saline is a crystalloid solution that has been widely used for fluid resuscitation and maintenance in intensive care units (ICUs). It's a solution of sodium chloride in water. However, recent research has raised concerns about its routine use due to potential complications like hyperchloremia, metabolic acidosis, and acute kidney injury. This is significant because, for many years, saline has been the default choice, and these findings suggest a need to re-evaluate its safety compared to alternative solutions.

What are balanced crystalloid solutions, and why are they being considered as an alternative to saline?

Balanced crystalloid solutions are intravenous fluids designed to closely mimic the electrolyte composition of blood plasma. They typically contain sodium, chloride, potassium, calcium, and magnesium in concentrations similar to those found in the body. They're important because they aim to minimize the risk of electrolyte imbalances and related complications that can occur with saline, such as hyperchloremia and metabolic acidosis. The potential implication is a reduced risk of acute kidney injury and other adverse outcomes in critically ill patients.

What did the meta-analysis actually compare, and why is this comparison important?

The meta-analysis compared the use of saline to balanced crystalloid solutions in adult ICU patients. It evaluated whether there was a difference in mortality rates between patients who received saline versus those who received balanced crystalloids for resuscitation or maintenance. The importance of this comparison lies in determining which fluid type is safer and more effective for critically ill patients, ultimately impacting patient survival. The odds ratio (OR) for mortality was 1.0972 (95% CI: 1.0049-1.1979), suggesting a roughly 10% increase in the odds of death with saline use.

What are the potential implications of the meta-analysis findings for patient care in the ICU?

The meta-analysis suggests that using saline in ICU patients may be associated with increased mortality compared to using balanced crystalloid solutions. This finding implies that the choice of intravenous fluids can significantly impact patient outcomes, and it highlights the need for healthcare providers to carefully consider the potential risks and benefits of each fluid type. This could lead to a shift in clinical practice towards more frequent use of balanced crystalloid solutions in critically ill patients.

What factors should doctors consider when deciding whether to use saline or balanced crystalloid solutions for a patient?

Some factors to consider include the patient's specific clinical condition, electrolyte balance, kidney function, and the potential risks and benefits of each fluid type. Healthcare providers should stay updated on the latest research and guidelines regarding fluid therapy in critically ill patients. The availability and cost of different solutions may also play a role. A personalized approach that takes into account the individual patient's needs is crucial for optimizing outcomes.