Abstract 1: Balanced Solution vs 0.9% Saline on Mortality: The BaSICS RCT

Effect of intravenous fluid treatment with a balanced solution vs 0.9% saline solution on mortality in critically ill patients: the BaSICS randomized clinical trial Zampieri FG, Machado FR, Biondi RS, et al. JAMA. 2021;326(9):818-829.

SUMMARY:

• For decades, almost all patients requiring IV fluids have been given normal saline, but several studies in recent years have called this practice into question.
• Most notably, the Isotonic Solutions and Major Adverse Renal Events Trial (SMART) found a lower rate of major adverse kidney events (MAKE 30) among ICU patients receiving balanced crystalloids. Some people felt that this finding was a game changer; others felt that the composite outcome was not very compelling, because the total fluid received (approximately 1 L) was too small to actually make a difference, and the cluster randomization could have introduced bias.
• This article reports findings from the Balanced Solutions in Intensive Care Study (BaSICS), a double-blind RCT conducted at 75 ICUs in Brazil with a primary outcome of 90-day survival.
• The study enrolled ICU-admitted patients whom the attending physician believed to need fluid expansion and who were at risk of kidney injury (age above 65 years, hypotension, sepsis, mechanical or noninvasive ventilation for at least 12 hours, oliguria, elevated creatinine, cirrhosis, or acute liver failure).
• The patients were randomized to receive 500-mL bags of either normal saline (NS) Plasma-Lyte labeled with only a letter) for all fluids.
• The study randomized 11,052 patients but excluded 486 (mostly because of refusal to provide consent), leaving 10,520 patients for analysis. The baseline characteristics were very similar between groups (mean age of 61.1 years, 44.2% women, just under 20% septic, 60.6% hypotensive, and 44.3% requiring invasive ventilation).
• Approximately 68% of the patients received a bolus before enrollment, and 45% received a volume >1 L.
• Patients in both groups received a median of 1.5 L fluid on the first day after enrollment and 4.1 L during the first 3 days.
• Primary outcomes are reported for all but 25 patients: the 90-day mortality was 26.4% for balanced solution vs 27.2% for NS (P = .47).
• The authors examined 19 secondary outcomes. Notably, the MAKE 30 renal replacement therapy outcome was not statistically different between groups (27.8% vs 28.9%).
• Analysis of multiple subgroups revealed only 1 with a statistically significant interaction: among patients with traumatic brain injury, the 90-day mortality was 31.3% for balanced solution vs 21.1% for NS. Although not described in the text, the 90-day mortality among patients with sepsis was 46.7% vs 49.0%.
• This is a very well-done, large blinded RCT with a 0.2% rate of loss to follow-up.
• Some study weaknesses are that approximately one-third of the patients received some fluids before randomization; only 1 type of balanced solution was used, although several are available; and a large portion of patients appeared to be surgical ICU patients, thus potentially decreasing the overall trial mortality.

PMID: 34375394

EDITOR’S COMMENTARY: In this double-blind RCT from Brazil, among patients in the ICU who required fluids, the authors did not find a significant difference in 90-day mortality between balanced solution and NS. The study was very well conducted, with an amazing follow-up rate, but it did have some limitations, including a potential for contamination, because fluids were given before randomization. Data are conflicting on the topic, and you will probably be able to interpret these data to strengthen your own opinion. But if you are looking for evidence that 1 strategy is just wrong, this is not it.

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