Addressing the inadvertent sodium and chloride burden in critically ill patients: a prospective before-and-after study in a tertiary mixed intensive care unit population

Background: Inadvertent fluid loading - and resultant sodium and chloride - is common in critically ill patients. Sources such as fluid used as vehicles for drug infusions and boluses (fluid creep) and maintenance fluid are a common cause. We hypothesised that total sodium and chloride loading can be safely reduced in critically ill patients both by the use of 5% glucose as a diluent for infusions and boluses, when possible, and by its use as a maintenance fluid. Methods: This was a prospective before-and-after study design in a single centre tertiary mixed intensive care unit (ICU). Comprehensive data about patient demographics, sources of fluid, feeds, intravenous drugs, fluid balance and electrolyte levels were collected for 4 weeks before and after the intervention (2016 and 2017). The amount of administered sodium was estimated from these sources. Results: There were 146 patients (643 study days) and 133 patients (684 study days) examined in 2016 and 2017 respectively. The change of practice lead to an increase in the use of 5% glucose as the maintenance fluid and as a diluent, which resulted in a decrease in the total daily administered sodium from a median of 197 mmol (interquartile range [(QR], 155-328 mmol) to a median of 109 mmol (IQR, 77-288 mmol) (P = 0.0001). It also resulted in decrease in daily fluid balance, plasma chloride and ICU acquired hypernatraemia. Conclusions: It is safely possible to decrease the total sodium and chloride loading to ICU patients by intervening on fluid creep and on maintenance fluid types. This intervention was accompanied by favourable changes in serum electrolyte and fluid balance.