Balanced crystalloids in the acutely ill patient.

Administration of intravenous fluids is the most common therapy given to patients admitted to a hospital. Evidence suggests that the use of normal saline (NS) in large quantities is not without adverse effects. Balanced salt solutions (BSS) contain bicarbonate or one of its precursors that act as a buffer, and the electrolyte composition resembles that of plasma. We reviewed studies across different setups such as intensive care units (ICUs), major surgeries, renal transplants and emergency departments to identify the effect(s) of NS and to find evidence favouring the use of BSS over NS. The use of NS is strongly associated with hyperchloraemic acidosis in almost all the studies. In the largest and latest trial in ICUs, it was found that higher chloride levels were associated with renal injury. No significant difference was found in mortality in any of the trials. In surgical patients, studies found only transient hyperchloraemia and increase in the base deficit in patients receiving NS. Systematic reviews and meta-analyses did not find any significant differences in adverse outcomes such as the need for renal replacement therapy or mortality with the use of saline; however, blood chloride levels were consistently higher with saline compared to BSS. There is a need for larger trials with better methodology to determine if the physiological benefits of BSS translate into better clinical outcomes.