#97 Respiratory acidosis as risk factor for mortality in older patients with acute kidney injury that require dialysis

Abstract Background and Aims Patients older than 65 years old with chronic kidney disease (CKD) particularly those who require renal replacement (RRT) are a growing population and some tools have been developed to help clinician and patients to make decisions regarding. However, information about patients with acute kidney injury on dialysis (AKI-D) is scarce. In this study we describe a group of 65 years and older patients admitted due to respiratory diseases that developed AKI and required RRT. We aim to identify risk factors associated with mortality in this population. Method This study is a retrospective analysis that included 118 patients admitted to our hospital between May 2022 and April 2024. We performed descriptive statistics with means and standard deviations for normally distributed continuous variables, medians and interquartile ranges for non-parametric distributions, and proportions for categorical variables. Patients were stratified according to their initial arterial partial pressure of CO2 (pCO2) values at the start of haemodialysis. The comparison between survivors and non-survivors was conducted using Fisher's exact test for categorical variables and the Mann-Whitney U test for continuous variables. A logistic regression analysis was used to identify the association between the pCO2 range tertiles and mortality. All statistical tests were two-tailed, and a p-value <0.05 was considered statistically significant. Kaplan-Meier survival analysis was performed to assess the time to death, comparing the pCO2 tertiles. SPSS version 27 was used. Results The patients were classified in two groups: survivors and not survivors. Overall, the mean age was 75.91 years, 55.93% of the patients were male; mean BMI was 27.94 kg/m2. As comorbidities 48.31% had diabetes, hypertension was found in 63.56% of patients. In the multivariate analysis, adjusted for gender and age (CI 95%) having a determination of CO2p >45 mmHg at the beginning of dialysis had an OR 4.066 (1.517–10.899, p 0.005) for mortality. Conclusion This study suggests that elevated pCO2 levels in the early stages of respiratory distress may indicate a more severe underlying condition, which could negatively impact short-term prognosis and recovery outcomes. Further research is needed to fully understand the underlying mechanisms of this phenomenon, this find could help clinicians, patients and their families to make better informed decisions.