Written by Clay Smith
Use of balanced fluid, such as LR, did not increase the risk of severe hyperkalemia, even when given to patients with a K of 6.5 mmol/L.
Why does this matter?
We covered SMART a while back. And we covered when NOT to use LR. LR has a small amount of potassium but has lower chloride and pH around 6.5. Normal saline (NS) has a lower pH, higher chloride, and potential for hyperchloremic metabolic acidosis, which favors a shift of potassium out of cells. Should we used balanced fluids like LR for hyperkalemic patients, or is NS better?
Restoring potassium balance
This was a secondary analysis of the SMART trial including 187 patients with hyperkalemia (>6.5mmol/L) and 1,324 with acute kidney injury on ICU admission, that were evenly split between the balanced fluid and NS cohorts. There was no statistical difference in severe hyperkalemia (>7.5) among patients with initial hyperkalemia: 8 patients (8.5%), balanced fluid; 13 patients (14.0%), NS (aOR 0.57, 95%CI 0.22-1.46; P=0.24). As in SMART, fewer of these patients needed renal replacement therapy (RRT) or developed new or worsening AKI. Patients with AKI on ICU admission also had no statistical difference in progression to severe hyperkalemia: 3 (0.4%), balanced fluid; 9 (1.4%), NS (aOR 0.33, 95%CI 0.09-1.25; P=0.10). Statistically fewer balanced fluid patients needed RRT. Potassium lowering therapies were no different between groups. This is a dogma-buster. It’s reasonable to choose LR to treat hyperkalemia over NS.
Balanced Crystalloids versus Saline in Critically Ill Adults with Hyperkalemia or Acute Kidney Injury: Secondary Analysis of a Clinical Trial. Am J Respir Crit Care Med. 2021 Jan 27. doi: 10.1164/rccm.202011-4122LE. Online ahead of print.