Sodium Administration and the Contribution of Fluid Creep to the Sodium Burden of Hospitalized Dogs in the ICU

OBJECTIVE: To assess the fluid volume and quantity of sodium administered each day to a population of hospitalized dogs and evaluate the major sources of administered fluid volume and sodium. DESIGN: Prospective, observational study. SETTING: University teaching hospital. ANIMALS: Twenty-nine dogs expected to require ICU hospitalization for at least 24 h. INTERVENTIONS: All sources, types, and volumes of fluid administered were recorded. The volume and sodium content of each fluid source administered daily were calculated. Fluid creep was defined as fluid given as drugs, diluents, and intravenous flush. MEASUREMENTS AND MAIN RESULTS: The mean (SD) daily fluid volume (mL/kg/day) and mean (SD) sodium administered (mEq/kg/day) for all dogs were 64.6 (±36.9) mL/kg/day and 8 (±4.6) mEq/kg/day (Day 1), 48.6 (±36.3) mL/kg/day and 6.2 (±4.5) mEq/kg/day (Day 2), and 43.1 (±32.1) mL/kg/day and 5.7 (± 4.2) mEq/kg/day (Day 3), respectively. Total fluid volume and sodium administration significantly decreased during hospitalization (p = 0.002 and p = 0.002, respectively). Fluid creep accounted for a median volume of 5.6, 4.6, and 2.7 mL/kg/day, and a median sodium content of 0.35, 0.28, and 0.22 mEq/kg/day on Days 1, 2, and 3, respectively. Daily total fluid creep volume decreased during hospitalization (p = 0.016), while daily fluid creep sodium content did not change (p = 0.06). There was no difference in proportional contribution of fluid creep to volume or sodium burden from Day 1 to 3 (p = 0.8, p = 0.6). CONCLUSIONS: Critically ill dogs have a clinically important sodium burden during hospitalization. Fluid creep accounts for a small but constant source of sodium administration despite significantly reduced fluid volumes over the course of hospitalization.