A comparison of balanced and unbalanced crystalloid solutions in surgery patient outcomes

Introduction The objective of this study was to evaluate adverse patient outcomes associated with the choice of intravenous fluid administered during general anaesthesia. Methods This study was a retrospective chart review of vascular surgery patients at a Canadian tertiary care hospital. Patients were separated into three groups: those who were intraoperatively administered normal saline (NS), balanced crystalloids, or a combination of both solutions. Multivariate analysis was performed to determine association between volume of each fluid type administered and adverse outcomes including in-hospital mortality, prolonged intensive care unit admission, vasopressor requirement, ventilator requirement, hemodialysis requirement, and a composite endpoint of any of these adverse events occurring. Results Overall, 796 vascular surgery patients were included in the analysis. There were 425 patients who received balanced crystalloids, 158 patients who received NS, and 213 patients received both balanced crystalloids and NS. Groups were similar in age (P = 0.06), but varied in gender (P < 0.001) and overall health (ASA ≥ 2; P = 0.027). The most common adverse event was ventilator requirement (NS: 27.9%, balanced: 7.5%, both: 38.0%; P < 0.001). Mortality was lowest in the group that received balanced fluids (NS: 12.0%, balanced: 5.9%, both: 10.8%; P = 0.018). Patients who were administered NS or both fluids were more likely to reach the composite endpoint than patients receiving balanced crystalloid alone. Conclusion The administration of an unbalanced crystalloid solution was associated with poor patient outcomes in our study population.