Association between postoperative changes in natremia and outcomes in patients undergoing elective craniotomy

Postoperative dysnatremias, characterized by imbalances in serum sodium levels, have been linked to increased resource utilization and mortality in surgical and intensive care patients. The management of dysnatremias may involve medical interventions based on changes in sodium levels. In this study, we aimed to investigate the impact of postoperative changes in natremia on outcomes specifically in patients undergoing craniotomy.We conducted a retrospective analysis of patient records from the Department of Neurosurgery at West China Hospital, Sichuan University, covering the period from January 2011 to March 2021. We compared the highest and lowest sodium values in the first 14 postoperative days with the baseline values to define four categories for analysis: no change < 5 mmol/L; decrease > 5 mmol/L; increase > 5 mmol/L; both increase and decrease > 5 mmol/L. The primary outcome measure was 30-day mortality.A total of 12,713 patients were included in the study, and the overall postoperative mortality rate at 30 days was 2.1% (264 patients). The increase in sodium levels carried a particularly high risk, with a tenfold increase (OR 10.21; 95% CI 7.25-14.39) compared to patients with minimal or no change. Decreases in sodium levels were associated with an increase in mortality (OR 1.60; 95% CI 1.11-2.23).Moreover, the study revealed that postoperative sodium decrease was correlated with various complications, such as deep venous thrombosis, pneumonia, intracranial infection, urinary infection, seizures, myocardial infarction, and prolonged hospital length of stay. On the other hand, postoperative sodium increases were associated with acute kidney injury, deep venous thrombosis, pneumonia, intracranial infection, urinary infection, surgical site infection, seizures, myocardial infarction, and prolonged hospital length of stay.Changes in postoperative sodium levels were associated with increased complications, prolonged length of hospital stay, and 30-day mortality. Moreover, the severity of sodium change values correlated with higher mortality rates.