Hyponatraemia, AKI, and urinary retention following elective joint arthroplasty

Abstract Background Acute kidney injury (AKI) and hyponatraemia are common postoperative complications following elective joint replacement surgery, often related to fluid and electrolyte imbalances. Dehydration can contribute to AKI, whereas excessive fluid administration may lead to hyponatraemia. Additionally, urinary retention can mimic AKI by reducing urine output, potentially resulting in unnecessary fluid administration and dilutional hyponatraemia. This study aims to improve postoperative fluid-electrolyte management by differentiating AKI from urinary retention and reducing the incidence of hyponatraemia and fluid overload. Methods Data from 616 patients undergoing elective joint replacement surgery over a six-month period were retrospectively reviewed, including electronic records, laboratory results, and fluid balance charts. Following this, an intervention incorporating routine bladder ultrasound scans into fluid management was implemented prospectively. The incidence of AKI and hyponatraemia before and after the intervention were compared using the chi-square test to evaluate the effectiveness of routine bladder scanning. Results The incidence of AKI was 1.2%, while hyponatraemia was observed in 38.3% of patients pre-intervention. After introducing routine bladder scanning, the incidence of AKI remained unchanged; however, the incidence of hyponatraemia significantly decreased to 6.5%. Statistical analysis demonstrated a chi-square value of 30.33 ( p < 0.00001), and, with Yates correction, 28.93 ( p < 0.00001), indicating a significant reduction in hyponatraemia incidence following the intervention. Conclusion Hyponatraemia is a common complication following joint replacement surgery that warrants clinical attention. Implementing routine bladder scanning as part of postoperative fluid management can significantly reduce its prevalence. Ongoing education and targeted interventions are recommended to optimise patient outcomes. Clinical trial number Not applicable. We were advised that as no new interventions were carried out there was no need to register this study.