A burden of fluid, sodium, and chloride due to intravenous fluid therapy in patients with respiratory support: a post-hoc analysis of a multicenter cohort study

Background: Fluid creep, including fluids administered as drug diluents and for the maintenance of catheter patency, is the major source of fluid intake in critically ill patients. Although hypoxemia may lead to fluid restriction, the epidemiology of fluid creep in patients with hypoxemia is unclear. This study aimed to address the burden due to fluid creep among patients with respiratory support according to oxygenation status. Methods: We conducted a post-hoc analysis of a prospective multicenter cohort study conducted in 23 intensive care units (ICUs) in Japan from January to March 2018. Consecutive adult patients who underwent invasive or noninvasive ventilation upon ICU admission and stayed in the ICU for more than 24 h were included. We excluded the following patients when no fluids were administered within 24 h of ICU admission and no records of the ratio of arterial oxygen partial pressure to fractional inspired oxygen. We investigated fluid therapy until 7 days after ICU admission according to oxygenation status. Fluid creep was defined as the fluids administered as drug diluents and for the maintenance of catheter patency when administered at ≤ 20 mL/h. Results: Among the 588 included patients, the median fluid creep within 24 h of ICU admission was 661 mL (25.2% of the total intravenous-fluid volume), and the proportion of fluid creep gradually increased throughout the ICU stay. Fluid creep tended to decrease throughout ICU days in patients without hypoxemia and in those with mild hypoxemia (p < 0.001 in both patients), but no significant trend was observed in those with severe hypoxemia (p = 0.159). Similar trends have been observed in the proportions of sodium and chloride caused by fluid creep. Conclusions: Fluid creep was the major source of fluid intake among patients with respiratory support, and the burden due to fluid creep was prolonged in those with severe hypoxemia. However, these findings may not be conclusive as this was an observational study. Interventional studies are, therefore, warranted to assess the feasibility of fluid creep restriction. Trial registration UMIN-CTR, the Japanese clinical trial registry (registration number: UMIN 000028019, July 1, 2017).