# Peak Lactate Within 24 h and Mortality in Septic Shock Patients Receiving Continuous Renal Replacement Therapy: A Real-World Cohort from an Asian ICU (2018–2020)

## TL;DR

This study shows that the highest lactate level within 24 hours is a strong predictor of death in septic shock patients undergoing kidney therapy in Asian ICUs.

## Contribution

The study demonstrates that peak lactate within 24 hours is a reliable mortality predictor in septic shock patients receiving CRRT in Asian ICU settings.

## Key findings

- Higher peak lactate within 24 hours was independently associated with increased 28-day mortality.
- Peak lactate outperformed APACHE II in predicting mortality (AUC 0.78 vs. 0.69).
- Mortality increased progressively across lactate quartiles, with the highest quartile at 68.1%.

## Abstract

Background: Serum lactate is a key biomarker of tissue hypoperfusion and metabolic stress in sepsis. Although lactate clearance is widely recognized, many intensive care units record only a peak lactate within 24 h (pLac-24h). The prognostic value of pLac-24h among patients receiving blood purification therapy remains unclear in Asian intensive care settings. Methods: We retrospectively analyzed the 2018–2020 ICU dataset from MacKay Memorial Hospital, Taiwan. Among 16,693 adult ICU admissions, 2506 patients received continuous renal replacement therapy (CRRT) as blood purification for severe sepsis or septic shock. Of these, 1264 (50.4%) had available pLac-24h data, and 27 (1.1%) also required extracorporeal membrane oxygenation (ECMO). The primary outcome was 28-day all-cause mortality. Multivariate logistic regression adjusted for age, sex, APACHE II score, infection source, and CRRT/ECMO use. Discrimination was evaluated by receiver operating characteristic (ROC) curves and decision-curve analysis. This analysis was conducted as a predefined sub-analysis of an institutional ICU database. Results: The mean age of the cohort was 65.7 ± 13.4 years, and 64.8% were male. Median pLac-24h was 5.1 mmol/L (IQR 3.2–8.6). The overall 28-day mortality among CRRT patients was 47.3%. Mortality rose progressively across pLac-24h quartiles (Q1–Q4: 28.9%, 39.4%, 54.7%, and 68.1%; p < 0.001). Each 1 mmol/L increase in pLac-24h independently predicted higher mortality (adjusted OR 1.18, 95% CI 1.10–1.26, p < 0.001). The area under the ROC curve for pLac-24h predicting 28-day mortality was 0.78 (95% CI 0.74–0.82), outperforming the APACHE II score (AUC 0.69, p = 0.02). Conclusions: In critically ill patients with septic shock undergoing CRRT, peak lactate within 24 h was a strong, independent predictor of 28-day mortality. pLac-24h offers a pragmatic, readily available prognostic indicator when serial lactate measurements are unavailable, supporting its integration into bedside risk assessment in real-world Asian ICU practice.