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Objective Nociceptive Assessment in Ventilated ICU Patients: A Feasibility Study Using Pupillometry and the Nociceptive Flexion Reflex
Published on: July 4, 2018
Association between potassium concentrations, variability and supplementation, and in-hospital mortality in ICU
Lilian Jo Engelhardt1, Felix Balzer1, Michael C Müller1
1Department of Anesthesiology and Operative Intensive Care Medicine (CCM, CVK), Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Augustenburger Platz 1, 13353, Berlin, Germany.
Insights
Optimal intensive care unit (ICU) potassium levels are between 3.5-4.0 mmol/l with minimal variability. Potassium supplementation may increase mortality, warranting critical discussion of current criteria.
Area of Science:
- Critical Care Medicine
- Clinical Chemistry
- Medical Statistics
Background:
- Serum potassium concentrations typically range from 3.5 to 5.0 mmol/l.
- Standardized protocols for potassium management in the ICU are lacking.
- This study investigates potassium levels, variability, and supplementation in relation to in-hospital mortality.
Purpose of the Study:
- To analyze the association between serum potassium concentrations, variability, and supplementation with in-hospital mortality in ICU patients.
- To identify optimal potassium target ranges and assess the impact of supplementation on patient outcomes.
Main Methods:
- Retrospective analysis of 53,248 adult ICU patients with over 1.3 million potassium values (2006-2018).
- Patients categorized by mean potassium concentrations and variability (standard deviation).
- Binary logistic regression and Kaplan-Meier survival analysis used to assess mortality associations; subanalysis on potassium supplementation.
Main Results:
- Lowest in-hospital mortality (3.7%) observed in patients with mean potassium of 3.5-4.0 mmol/l and low variability (1st SD).
- Potassium supplementation in 57.5% of a subgroup (2013-2018) was linked to increased mortality across multiple potassium categories and variability levels (p < 0.001).
Conclusions:
- ICU patients may benefit from a target serum potassium range of 3.5-4.0 mmol/l with minimal variability.
- Further research is needed to establish clear potassium target ranges and critically evaluate criteria for potassium supplementation.
Background:
Serum potassium concentrations are commonly between 3.5 and 5.0 mmol/l. Standardised protocols for potassium range and supplementation in the ICU are lacking. The purpose of this retrospective analysis of ICU patients was to investigate potassium concentrations, variability and supplementation, and their association with in-hospital mortality.
Methods:
ICU patients ≥ 18 years, with ≥ 2 serum potassium values, treated at the Charité - Universitätsmedizin Berlin between 2006 and 2018 were eligible for inclusion. We categorised into groups of mean potassium concentrations: < 3.0, 3.0-3.5, > 3.5-4.0, > 4.0-4.5, > 4.5-5.0, > 5.0-5.5, > 5.5 mmol/l and potassium variability: 1st, 2nd and ≥ 3rd standard deviation (SD). We analysed the association between the particular groups and in-hospital mortality and performed binary logistic regression analysis. Survival curves were performed according to Kaplan-Meier and tested by Log-Rank. In a subanalysis, the association between potassium supplementation and in-hospital mortality was investigated.
Results:
In 53,248 ICU patients with 1,337,742 potassium values, the lowest mortality (3.7%) was observed in patients with mean potassium concentrations between > 3.5 and 4.0 mmol/l and a low potassium variability within the 1st SD. Binary logistic regression confirmed these results. In a subanalysis of 22,406 ICU patients (ICU admission: 2013-2018), 12,892 (57.5%) received oral and/or intravenous potassium supplementation. Potassium supplementation was associated with an increase in in-hospital mortality in potassium categories from > 3.5 to 4.5 mmol/l and in the 1st, 2nd and ≥ 3rd SD (p < 0.001 each).
Conclusions:
ICU patients may benefit from a target range between 3.5 and 4.0 mmol/l and a minimal potassium variability. Clear potassium target ranges have to be determined. Criteria for widely applied potassium supplementation should be critically discussed. Trial registration German Clinical Trials Register, DRKS00016411. Retrospectively registered 11 January 2019, http://www.drks.de/DRKS00016411.
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