Fluid Management in Critical Care: New Insights Into Optimal Fluid Therapy

Background: Fluid management is a crucial critical care component, influencing outcomes such as organ function, renal integrity, and survival in critically ill patients. Recent evidence suggests that balanced crystalloids may offer advantages over isotonic saline, particularly in reducing the risk of acute kidney injury (AKI) and other complications. This study aimed to evaluate the impact of balanced crystalloids versus isotonic saline on clinical outcomes in the intensive care unit (ICU), focusing on AKI, renal replacement therapy (RRT), and mortality. The study also assessed the role of fluid restriction in specific patient populations, including those with acute respiratory distress syndrome (ARDS), sepsis, and heart failure.

Methods: A retrospective cohort study included 600 adult patients admitted to the ICU who received fluid therapy between January 2023 and January 2024. Patients were categorized into two groups based on the type of fluid received: 300 patients received balanced crystalloids and 300 received isotonic saline. Outcomes of interest included the incidence of AKI, the need for RRT, overall ICU mortality, oxygenation status (PaO₂/FiO₂ ratio), duration of mechanical ventilation, cumulative fluid balance, and length of ICU stay. Statistical analyses included multivariate logistic regression to adjust for potential confounders.

Results: The incidence of AKI was significantly lower in the balanced crystalloids group (12% vs. 22%, p = 0.01), with an adjusted odds ratio (OR) of 0.50 (95% CI 0.32-0.78, p = 0.002). The need for RRT was also reduced (8% vs. 15%, p = 0.03), with an adjusted OR of 0.55 (95% CI 0.30-0.95, p = 0.03). Although ICU mortality was lower in the balanced crystalloids group (18% vs. 24%), this difference did not reach statistical significance (p = 0.08). Subgroup analysis showed that in ARDS patients, fluid restriction combined with balanced crystalloids improved oxygenation (PaO₂/FiO₂ ratio of 220 vs. 180, p = 0.02) and reduced the duration of mechanical ventilation (six vs. nine days, p = 0.01). Similar benefits were observed in sepsis and heart failure patients.

Conclusion: Balanced crystalloids are associated with a significant reduction in AKI incidence and RRT requirement compared to isotonic saline. Fluid restriction, particularly when combined with balanced crystalloids, improves clinical outcomes in patients with ARDS, sepsis, and heart failure. These findings support the preferential use of balanced crystalloids in critically ill patients and highlight the importance of individualized fluid management strategies in the ICU. Further research is needed to confirm these benefits and optimize fluid therapy protocols in diverse ICU populations.