Intravenous (IV) fluids are a cornerstone of modern medicine, used extensively in hospitals for resuscitation, maintenance, and replacement therapy. Normal saline (0.9% sodium chloride) has been the most commonly used IV fluid worldwide for decades. However, recent research has raised concerns about its potential adverse effects, particularly its high chloride content, which can lead to hyperchloremic acidosis and kidney injury.
In response, balanced crystalloid solutions, such as lactated Ringer's and Plasma-Lyte, have gained attention as potentially safer alternatives. This article explores the findings of recent trials comparing balanced crystalloids to conventional IV fluids.
While widely used the problem with Normal Saline is that it has a chloride concentration significantly higher than that of human plasma. This can disrupt the body's acid-base balance, leading to hyperchloremic metabolic acidosis, a condition associated with renal vasoconstriction, reduced glomerular filtration rate, and acute kidney injury (AKI).
Additionally, normal saline lacks other electrolytes, such as potassium, calcium, and magnesium, which are present in balanced crystalloids.
Balanced crystalloids, on the other hand, have an electrolyte composition closer to that of plasma and contain buffers like lactate or acetate to help maintain physiological pH. (They have a SIG of around 40, which is equivalent to the normal SIG of Plasma). These properties make them theoretically and physiologically more appropriate for IV fluid therapy.
Key Clinical Trials Several large-scale randomized controlled trials (RCTs) have recently investigated the clinical outcomes of balanced crystalloids versus normal saline in various patient populations.
SMART Trial (2018)
The Isotonic Solutions and Major Adverse Renal Events Trial (SMART) was a pragmatic, cluster-randomized, multiple-crossover trial conducted in five intensive care units (ICUs) at Vanderbilt University Medical Center. It included over 15,000 critically ill patients randomized to receive either balanced crystalloids (lactated Ringer's or Plasma-Lyte) or normal saline. Findings: The trial found that patients receiving balanced crystalloids had a lower incidence of major adverse kidney events within 30 days (MAKE30), a composite outcome of death, dialysis, or persistent renal dysfunction, compared to those receiving normal saline (14.3% vs. 15.4%). Implications: The SMART trial provided strong evidence that balanced crystalloids may reduce the risk of kidney injury and improve outcomes in critically ill patients.
SALT-ED Trial (2018)
The Saline Against Lactated Ringer's or Plasma-Lyte in the Emergency Department (SALT-ED) trial, conducted alongside the SMART trial, focused on non-critically ill patients treated in the emergency department. Over 13,000 patients were randomized to receive either balanced crystalloids or normal saline.
Findings:
The trial found no significant difference in hospital-free days between the two groups. However, patients receiving balanced crystalloids had a lower incidence of MAKE30 (4.7% vs. 5.6%).
Implications:
The SALT-ED trial suggested that balanced crystalloids may also benefit non-critically ill patients, particularly in reducing kidney-related adverse events.
BaSICS Trial (2021)
The Balanced Solution versus Saline in Intensive Care Study (BaSICS) was a large RCT conducted in 75 ICUs across Brazil, involving over 11,000 critically ill patients. Patients were randomized to receive either Plasma-Lyte 148 or normal saline.
Findings:
The trial found no significant difference in 90-day mortality or AKI between the two groups. However, a subgroup analysis suggested potential benefits for patients with traumatic brain injury or those receiving larger volumes of fluids.
Implications:
The BaSICS trial highlighted the complexity of fluid therapy and suggested that the benefits of balanced crystalloids may vary depending on patient subgroups and clinical contexts.
PLUS Trial (2022)
The Plasma-Lyte 148 versus Saline (PLUS) trial, conducted in 53 ICUs in Australia and New Zealand, randomized over 5,000 critically ill patients to receive either Plasma-Lyte 148 or normal saline.
Findings:
The trial found no significant difference in 90-day mortality or AKI between the two groups. However, patients receiving Plasma-Lyte 148 had a lower incidence of hyperchloremia and metabolic acidosis.
Implications:
The PLUS trial reinforced the safety of balanced crystalloids but did not demonstrate a clear mortality benefit over normal saline.
Clinical Implications and Future Directions
The findings of these trials suggest that balanced crystalloids are at least as safe as normal saline and may offer specific benefits, particularly in reducing kidney-related adverse events. However, the lack of a consistent mortality benefit across all trials indicates that the choice of IV fluid should be tailored to individual patient needs and clinical contexts.
Future research should focus on identifying patient subgroups that may derive the greatest benefit from balanced crystalloids, such as those with sepsis, traumatic brain injury, or pre-existing kidney disease. Additionally, cost-effectiveness analyses are needed to evaluate the economic impact of the widespread adoption of balanced crystalloids.
Conclusion
Recent trials have significantly advanced our understanding of the role of balanced crystalloids versus conventional IV fluids. While normal saline remains a widely used and effective fluid, balanced crystalloids offer a physiologically more appropriate alternative with potential benefits in reducing kidney injury and metabolic disturbances. As the evidence continues to evolve, clinicians should consider patient-specific factors and the latest research when selecting IV fluids to optimize outcomes.
Comments
Post a Comment