Written by Aaron Lacy
A large RCT in Brazilian ICUs found no difference in 90-day mortality between patients who received balanced crystalloids versus normal saline (NS).
Why does this matter?
Two large studies, SMART and SALT-ED, both showed that patients who received balanced crystalloids had better outcomes than those who received NS. This large ICU RCT did not show a statistically significant difference in mortality between the two. Does this minimize the impact of SMART and SALT-ED, or is there more to unpack from BaSICS?
Back to BaSICS or a changing of the times?
Yesterday we covered the first intervention arm of BaSICS which look at mortality in relation to fluid administration rate. This double-blind, randomized clinical trial in 75 Brazilian ICUs, with over 10,000 adult patients enrolled, also set out to measure 90-day mortality in patients randomized to either PlasmaLyte or NS. There was no significant mortality difference between PlasmaLyte (26.4%) and NS (27.2%) (aHR 0.97, CI 0.90-1.05, P=.47). A secondary outcome showed no significant difference in need for renal replacement therapy or doubled creatinine in balanced crystalloid group (27.8%) versus NS group (28.9%) (95% CI, 0.86-1.04). Although the primary and secondary outcomes measured differed slightly, this study contrasts with both SMART and SALT-ED, which showed decreased likelihood of a major adverse kidney event and decreased in-hospital mortality at 30 days. So, what gives? Does this study mean what fluid we use doesn’t matter?
You could read the abstract and conclude that there is no difference between balanced crystalloids and NS – but that’s not how we do things around here! There are several key points to unpack when comparing this trial with the two major RCTs that came before it.
The overall signal from the study still leans towards balanced crystalloids. While you do need to prove statistical significance to be practice changing (or not), BaSICS had ~4,300 fewer patients than SMART, and only looked at 90-day mortality as their primary outcome. If outcomes were similar to SMART and SALT-ED, perhaps with more patients, things might look different. Additionally, this study only looked at patients after they arrived in the ICU, and fluids patients received prior to this were NOT controlled or considered, which could be a huge factor in interpreting these results.
In the end, my big takeaway from this is there is no one-size-fits-all fluid. One subgroup from BaSICS showed statistically significant decrease in 90-day mortality in patients with TBI who received NS (21.1%) instead of PlasmaLyte (31.3%) (HR 1.48, 95% CI 1.03-2.12, P=0.02). LR is better for patients with DKA and sepsis, but it seems that NS is preferred in some other clinical scenarios. This is a vital topic to medical practice, and I am glad to see so many high-quality studies being put forward and can’t wait to see what’s next.
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. JAMA. 2021 Aug 10;e2111684. doi: 10.1001/jama.2021.11684. Online ahead of print.