Effects of sodium bicarbonate infusion on mortality in medical-surgical ICU patients with metabolic acidosis-A single-center propensity score matched analysis

J Waskowski; B Hess; L Cioccari; I Irincheeva; C A Pfortmueller; J C Schefold

doi:10.1016/j.medin.2021.04.010

Effects of sodium bicarbonate infusion on mortality in medical-surgical ICU patients with metabolic acidosis-A single-center propensity score matched analysis

Med Intensiva (Engl Ed). 2021 Jun 10:S0210-5691(21)00106-6. doi: 10.1016/j.medin.2021.04.010. Online ahead of print.

[Article in English, Spanish]

Authors

J Waskowski¹, B Hess², L Cioccari³, I Irincheeva⁴, C A Pfortmueller³, J C Schefold³

Affiliations

¹ Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland. Electronic address: jan.waskowski@insel.ch.
² Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; Center of Intensive Care Medicine, Luzerner Kantonsspital, Lucerne, Switzerland.
³ Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
⁴ CTU Bern, University of Bern, Switzerland.

PMID: 34120787
DOI: 10.1016/j.medin.2021.04.010

Abstract

Objective: Metabolic acidosis is associated with high mortality. Despite theoretical benefits of sodium-bicarbonate (SB), current evidence remains controversial. We investigated SB-related effects on outcomes in ICU patients with metabolic acidosis.

Design: Retrospective analysis.

Setting: Academic medical center.

Patients or participants: 971 ICU patients with metabolic acidosis defined as arterial pH<7.3 and CO₂<45mmHg treated between 2012 and 2016. A propensity score (PS) was estimated using logistic regression. Patients were matched in pairs using the PS.

Interventions: 441 patients were treated with SB 8.4% (SB-group) and n=530 patients were not (control group).

Main variables of interest: Primary outcome was all-cause mortality at ICU-discharge. Average Treatment Effect (ATE), Average Treatment effect in Treated (ATT), and estimated relative survival effects at 20 days were computed.

Results: In the full cohort, we observed considerable differences in pH, base excess, additional acidosis-related indices, and ICU mortality (controls 31% vs. SB-group 56%, p<.001) at baseline between the two groups. After PS-matching (n=174 in each group), no significant difference in ICU mortality was observed (controls 32% vs. SB-group 41%; p=.07). Odds ratios (OR) for ATE and ATT showed no association with ICU mortality (OR ATE: 1.08, 95%-CI 0.99-1.17; p=.08; OR ATT 1.09; 95%-CI 0.99-1.2; p=.09). Hazard ratios at 20-days (multivariable HR, matched sample n=348: 1.16, 95%-CI 0.86-1.56, p=.33) showed similar survival in the two study groups.

Conclusions: We did not observe effects of SB infusion on all-cause mortality in critically ill patients with metabolic acidosis.

Keywords: Acidosis metabólica; Bicarbonato de sodio; Critical illness; Enfermedad crítica; ICU; Metabolic acidosis; Mortalidad; Mortality; Sodium bicarbonate; UCI.