Acidemia subtypes in critically ill patients: An international cohort study

Katsunori Mochizuki; Tomoko Fujii; Eldho Paul; Matthew Anstey; Shigehiko Uchino; David V Pilcher; Rinaldo Bellomo

doi:10.1016/j.jcrc.2021.02.006

Acidemia subtypes in critically ill patients: An international cohort study

J Crit Care. 2021 Aug:64:10-17. doi: 10.1016/j.jcrc.2021.02.006. Epub 2021 Feb 26.

Authors

Katsunori Mochizuki¹, Tomoko Fujii², Eldho Paul³, Matthew Anstey⁴, Shigehiko Uchino⁵, David V Pilcher⁶, Rinaldo Bellomo⁷

Affiliations

¹ Australian and New Zealand Intensive Care Research Centre, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia; Department of Emergency and Critical Care Medicine, Shinshu University School of Medicine, Matsumoto, Nagano, Japan. Electronic address: katsunori.mochizuki@monash.edu.
² Australian and New Zealand Intensive Care Research Centre, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia; Intensive Care Unit, The Jikei University Hospital, Tokyo, Japan.
³ Australian and New Zealand Intensive Care Research Centre, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia.
⁴ Intensive Care, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia; School of Medicine, University of Western Australia, Nedlands, Western Australia, Australia.
⁵ Intensive Care Unit, The Jikei University Hospital, Tokyo, Japan.
⁶ Australian and New Zealand Intensive Care Research Centre, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia; Department of Intensive Care, The Alfred, Melbourne, Victoria, Australia; The Australian and New Zealand Intensive Care Society Centre for Outcome and Resource Evaluation, Camberwell, Victoria, Australia.
⁷ Australian and New Zealand Intensive Care Research Centre, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia; Department of Intensive Care, Austin Hospital, Heidelberg, Victoria, Australia; Department of Intensive Care, Royal Melbourne Hospital, Melbourne, Victoria, Australia; Centre for Integrated Critical Care, Department of Medicine, The University of Melbourne, Parkville, Victoria, Australia; Data Analytics Research and evaluation Centre, The University of Melbourne and Austin Hospital, Melbourne, Australia.

PMID: 33725556
DOI: 10.1016/j.jcrc.2021.02.006

Abstract

Purpose: To study the prevalence, characteristic, outcome, and acid-base biomarker predictors of outcome for different acidemia subtypes.

Methods: We used national intensive care databases from three countries and classified acidemia subtypes as metabolic (standard base excess [SBE] < -2 mEq/L only), respiratory (PaCO₂ > 42 mmHg only), and combined (both SBE < -2 mEq/L and PaCO₂ > 42 mmHg) based on blood gas analysis in the first 24 h after ICU admission. To investigate acid-base predictors for hospital mortality, we applied the area under the receiver operating characteristic curve approach.

Results: We screened 643,689 ICU patients (2014-2018) and detected acidemia in 57.8%. The most common subtype was metabolic (42.9%), followed by combined (30.3%) and respiratory (25.9%). Combined acidemia had a mortality of 12.7%, compared with 11% for metabolic and 5.5% for respiratory. For combined acidemia, the best predictor of hospital mortality was pH. However, for metabolic or respiratory acidemia, it was SBE or PaCO₂, respectively.

Conclusions: In ICU patients with acidemia, mortality differs according to subtype and is highest in the combined subtype. Best acid-base predictors of mortality also differ according to subtype with best performance for pH in combined, SBE in metabolic, and PaCO₂ in respiratory acidemia.

Keywords: Acidemia; Base excess; Metabolic acidosis; Mixed acidosis; Respiratory acidosis; pH.

MeSH terms

Acidosis* / epidemiology
Blood Gas Analysis
Cohort Studies
Critical Illness*
Humans
ROC Curve