In this episode, I’ll discuss the results of a pilot trial of sodium bicarbonate for metabolic acidosis in the ICU.
Sodium Bicarbonate is frequently given to ICU patients to correct metabolic acidosis however evidence to support this indication is lacking and sodium bicarb is not a benign intervention without risk of adverse effects.
In an effort to better quantify the potential benefits of this therapy, a group of authors recently published in Critical Care Medicine a pilot trial of sodium bicarbonate for metabolic acidosis in the ICU.
30 patients in 8 ICUs in 3 countries participated. As a pilot study, a major goal was looking at the feasibility on assessing eligibility, recruitment rate, protocol compliance, and acid–base group separation. However investigators also looked at a clinical outcome which was the number of hours alive and free of vasopressors on day 7.
To be eligible patients had to be 18 years or older, enrolled within 48 hours of admission to the ICU, receiving a vasopressor, and with metabolic acidosis (defined as pH less than 7.30, base excess less than –4 mEq/L, and Paco2 less than 45 mm Hg).
The placebo group received dextrose and the intervention group received sodium bicarb prepared as follows:
A 500 mL bag of D5W had 300 mL of D5W removed and 300 mL of sodium bicarbonate 8.4% added for a final concentration: 600 mEq/L. The study drug was given via continouus infusion at 100 mL/hr to achieve a target pH greater than or equal to 7.30 and a base excess greater than or equal to 0 mEq/L. The infusion was maintained until this target was reached and continued at a rate of 25 mL/hr thereafter for a maximum of 5 hours.
The authors judged the trial design to be feasible and that it justifies a larger study.
Seven days after randomization, patients in the sodium bicarbonate group had median hours alive and free of vasopressor that was 35 hours greater than the placebo group however this did not reach statistical significance. Recurrence of metabolic acidosis in the first 7 days of follow-up was statistically significantly lower in the sodium bicarbonate group and there were no adverse events reported.
While this study has aspects that appear to favor sodium bicarb use, the larger study will need to be completed before a definitive widespread recommendation to use bicarb to treat metabolic acidosis can be made.
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