Early 8.4% sodium bicarbonate and in-hospital mortality in cardiogenic shock with severe acidemia and hyperlactatemia: A two-hour landmark overlap-weighted retrospective cohort study
Xingwei Wang, Yang Gao, Qingbo Shi, Cao Ma, Yahui LiuObjective
To evaluate the association between early concentrated 8.4% sodium bicarbonate and subsequent in-hospital mortality in patients with cardiogenic shock, severe acidemia, and hyperlactatemia.
Methods
We conducted a retrospective two-hour landmark cohort study using the single-center MIMIC-IV v3.1 database. True time zero was the first time pH ≤7.20 and lactate ≥4 mmol/L were both known within a two-hour pairing window. Patients with pre-time-zero bicarbonate exposure, renal replacement therapy, or diabetic ketoacidosis were excluded. Patients alive and still hospitalized at two hours were classified according to 8.4% sodium bicarbonate administration during the 0- to 2-hour window. Propensity-score overlap weighting was used to balance baseline covariates. The primary outcome was subsequent in-hospital mortality.
Results
Among 489 landmark patients, 110 received early 8.4% bicarbonate and 379 did not. After overlap weighting, the maximum absolute standardized mean difference was 0.091. Weighted mortality was 80.4% with early bicarbonate versus 70.2% without early treatment, corresponding to a risk difference of 10.2 percentage points (95% CI, −0.1 to 20.4; P=.052) and a risk ratio of 1.145 (95% CI, 1.001–1.310; P=.049). Sensitivity analyses showed broadly consistent point estimates, although confidence intervals and target overlap populations varied.
Conclusions
Early 8.4% sodium bicarbonate did not demonstrate a survival benefit among patients who survived to the two-hour landmark. Estimates were directionally compatible with higher mortality, but residual confounding and statistical uncertainty preclude a causal conclusion of harm.