Purpose: We aimed to determine if balanced crystalloids compared with saline improve outcomes in critically ill adults admitted with low plasma bicarbonate.

Materials and methods: We performed a secondary analysis of the Isotonic Solutions and Major Adverse Renal Events Trial (SMART). We included patients who presented to the Emergency Department with a first measured plasma bicarbonate less than 20 mmol/L. Among these patients, we compared the effect of balanced crystalloid versus saline on the primary outcome of major adverse kidney events within 30 days (MAKE30), defined as a composite of death, new renal-replacement therapy, or persistent renal dysfunction (final inpatient creatinine ≥200% baseline). Secondary outcomes included 30 day in-hospital mortality, receipt of new RRT, persistent renal dysfunction, incident AKI, and vasopressor-free days.

Results: Among the 2029 patients with an initial plasma bicarbonate concentration < 20 mmol/L, there was no difference in the incidence of MAKE30 between those assigned to balanced crystalloid versus saline (21.8% vs 21.3%; P = 0.93). Secondary outcomes were similar between the balanced crystalloid and saline groups.

Conclusions: Among critically ill adults presenting to the Emergency Department, initial plasma bicarbonate concentration does not appear to be a useful marker to guide the selection of balanced crystalloid versus saline.