Improved kidney outcomes with intravenous balanced crystalloids instead of saline

Reference

Semler MW, Self WH, Wanderer JP, et al, for the SMART Investigators and the Pragmatic Critical Care Research Group. Balanced crystalloids versus saline in critically ill adults. N Engl J Med 2018;378(9):829-839.

Synopsis

These investigators enrolled 15,802 adult patients admitted to 5 intensive care units (ICUs) during an 11-month period at an academic medical center. The participating ICUs were assigned to use either balanced crystalloids or saline for 1 month and then alternated to the other fluid each subsequent month. Patients assigned to saline received 0.9% sodium chloride; patients assigned to balanced crystalloids received either lactated Ringer's solution or Plasma-lyte A. The study was nonmasked. Baseline characteristics were similar in the 2 groups: median age was 58 years, one-quarter required vasopressors, and more than one-third required mechanical ventilation at enrollment. Overall, 5% of patients in the balanced crystalloid group and 4% in the saline group received both intravenous fluid types as a result of remaining in the ICU from the end of one month to the start of the next. For the composite outcome of major adverse kidney events (including all-cause death, need for new renal replacement therapy, or persistent acute renal dysfunction at either 30 days or at hospital discharge, whichever came first) patients in the balanced crystalloid group fared better than those in the saline group (14.3% vs 15.4%; odds ratio [OR] 0.90; 95% CI 0.82 - 0.99; P = .04). A greater benefit was noted for patients who received larger volumes of intravenous fluid and for those with sepsis. Additionally, there was a trend toward decreased 30-day in-hospital mortality overall in the balanced crystalloids group (10.3% vs 11.1%; P = .06), with a statistically significantly decreased number of deaths in the subset of septic patients (25.2% vs 29.4%; P = .02). No significant differences were noted in the individual outcomes of need for new renal replacement therapy or persistent acute renal dysfunction. In a second trial by the same group comparing balanced crystalloids with normal saline in noncritically ill patients, no significant difference was seen in the primary outcome of the number of hospital-free days. However, a reduction of major adverse kidney events was again noted in the balanced crystalloid group (4.7% vs 5.6%; OR 0.82; 0.70 - 0.95; P = .01).