Among critically ill patients, the use of balanced solutions did not reduce 90-day mortality compared with normal saline in the BaSICS trial.
Among critically ill patients, intravenous fluids (IV) are used for intravascular volume replacement. Administration of such fluids is extremely common and it has been estimated that every day, over 20% of patients within an intensive care setting receive fluid therapy. In general terms, fluid therapy is required for several indications including impaired tissue perfusion, low cardiac output and abnormal vital signs, e.g., blood pressure, heart rate or urine output. The most commonly used IV fluid is saline solution (0.9% sodium chloride) although in recent years, there has been emerging evidence that IV fluids other than saline in critically ill patients may have a more favourable impact on mortality. Balanced IV fluids, for example, have been designed to be more aligned with the composition of serum and may have some advantages over saline. For example, one study in patients with sepsis, concluded that resuscitation with balanced fluids was associated with a lower risk of in-hospital mortality. In a 2018 study among critically ill adults, the use of a balanced crystalloid rather than saline, produced a lower rate of death compared to saline. The use of a balanced solution rather than saline has several other potential advantages, particularly in relations to adverse effects, since saline contains a higher concentration of chloride ions and has been associated with a hyperchloraemic metabolic acidosis and acute kidney injury.
However, the overall benefit of using a balanced IV fluid rather than saline is not always superior. For instance, the use of a balanced crystalloid did not reduce the incidence of acute kidney injury compared to saline within an intensive care unit (ICU). In trying to provide much needed clarity, the Balanced Solution versus Saline in Intensive Care Study (BaSICS) by a Brazilian group of clinicians was undertaken to compare the effectiveness and safety of balanced crystalloids compared with saline in critically ill patients. This trial undertaken at 75 intensive care units in Brazil, randomised patients admitted to an ICU to either saline or a balanced solution and the primary outcome was 90-day survival.
A total of 10,520 critically ill patients with a mean age of 61.1 years (44.2% female), were randomised to either balanced fluids or saline and patients in both groups received a median of 1.5 litres of fluid during the first day of enrolment. Of the whole cohort, 60.6% of patients had hypotension or vasopressor use and 44.3% required mechanical ventilation at enrolment. Within 90 days of enrolment, 26.4% of those assigned to balance fluids died compared to 27.2% given saline (adjusted hazard ratio, aHR = 0.97, 95% CI 0.90 – 1.05, p = 0.47).
The authors concluded that despite the potential advantages of balanced crystalloids over saline, there were no apparent mortality benefits.
Zampieri F et al. Effect of Intravenous Fluid Treatment with a Balanced Solution vs 0.9% Saline Solution on Mortality in Critically Ill Patients. The BaSICS Randomised Clinical Trial. JAMA 2021