Electrolyte Imbalance and Its Prognostic Impact on All-Cause Mortality in ICU Patients with Respiratory Failure

Objectives: Chronic obstructive pulmonary disease (COPD) and acute respiratory failure are critical clinical conditions associated with high mortality rates in intensive care units (ICUs). Electrolyte imbalances are significant variables that may influence all-cause ICU mortality in this patient group. In this study, we retrospectively investigated the relationship between sodium (Na⁺), chloride (Cl⁻), potassium (K⁺), calcium (Ca²⁺), and magnesium (Mg²⁺) levels and all-cause ICU mortality in patients followed up due to respiratory failure. Methods: A total of 1109 patients were analysed between January 2022 and January 2024. The electrolyte levels measured at ICU admission, demographic data, APACHE II and SOFA scores, arterial blood gas results, BUN and creatinine levels, need for non-invasive mechanical ventilation, length of ICU stay, and survival outcomes were assessed. Statistical analyses were performed using Kaplan-Meier survival analysis and Cox regression method. Results: Our findings showed that patients with low potassium and calcium levels had significantly higher mortality rates (p< 0.05). When sodium levels were divided into quartiles, mortality risk was found to be markedly increased in both the lowest (Q1) and highest (Q4) quartiles. Cox regression analysis revealed that the mortality risk in hyponatremic patients was 2.2 times higher than in normonatremic patients (p=0.005). In the hypernatremic group, the increased mortality risk was statistically borderline significant (p=0.06). Conclusion: Electrolyte imbalances are important predictors of mortality in patients with respiratory failure. Sodium levels exhibit a "U-shaped" relationship with mortality, with hyponatremia emerging as a prominent risk factor. Careful assessment of electrolyte imbalances is considered crucial in the clinical management of these patients.