The impact of serum potassium ion variability on 28-day mortality in ICU patients

Objective: Potassium ion disorders are prevalent among patients in Intensive Care Units (ICUs), yet there is a notable deficiency in established protocols and supplemental plans for potassium management. This retrospective study conducted at a single center aims to explore the relationship between potassium levels, their variability, and the 28-day mortality rate in ICU patients.

Methods: This study analyzed patients admitted to the ICU within one year. We assessed serum potassium variability using the coefficient of variation and categorized it into four quartile groups (Q1, Q2, Q3, Q4). Additionally, patients were classified into six groups based on serum potassium concentrations. The associations between these categories and the 28-day mortality rate were evaluated using binary logistic regression, adjusting for potential confounders.

Methods
Within 28 days of admission to the ICU, potassium levels were systematically measured every 12 hours. Data collection commenced from the first day of the patient's ICU stay, encompassing a comprehensive range of variables. These variables included demographic information (age, gender), the duration of the hospital stay, clinical outcomes at 28 days, heart rate, systolic and diastolic blood pressure, mean arterial pressure, the Sequential Organ Failure Assessment (SOFA) score, pH levels, eGFR, creatinine, bilirubin, blood glucose, urine output, and the administration of insulin, potassium chloride, and furosemide. For patients who die within 28 days, if the blood drawn before death happens to occur within 12 hours, the abnormal blood drawn results will be discarded and then incorporated into other blood drawn results at similar times. This approach was adopted to ensure the integrity of the data and to minimize the influence of external factors.