Timing of Fluid Overload and Association With Patient Outcome

Objectives: To determine if the timing of excess fluid accumulation (fluid overload) is associated with adverse patient outcomes. Design: Secondary analysis of a prospectively collected dataset. Setting: PICU of a tertiary care hospital. Patients: Children 3 months to 25 years old admitted to the PICU with expected length of stay greater than or equal to 48 hours. Interventions: Patients were dichotomized by time of peak overload: peak fluid overload from ICU admission (Day 0 ) to 48 hours (Day 3–7 ) and peak fluid overload value after 48 hours of ICU admission, as well as time of first-time negative daily fluid balance: net fluid out greater than net fluid in for that 24-hour period. Measurements and Main Results: There were 177 patients who met inclusion criteria, 92 (52%) male, with an overall mortality rate of 7% ( n = 12). There were no differences in severity of illness scores or fluid overload on Day 0 between peak fluid overload from ICU admission (Day 0 ) to 48 hours (Day 3–7 ) ( n = 97; 55%) and peak fluid overload value after 48 hours of ICU admission ( n = 80; 45%) groups. Peak fluid overload value after 48 hours of ICU admission was associated with a longer median ICU course (8 [4–15] vs 4 d [3–8 d]; p ≤ 0.001], hospital length of stay (18 [10–38) vs 12 [8–24]; p = 0.01], and increased risk of mortality ( n = 10 [13%] vs 2 [2%]; χ 2 = 7.6; p = 0.006]. ICU length of stay was also longer in the peak fluid overload value after 48 hours of ICU admission group when only patients with at least 7 days of ICU stay were analyzed ( p = 0.02). Timing of negative fluid balance was also correlated with outcome. Compared with Day 0–2 , a negative daily fluid balance on Day 3–7 was associated with increased length of mechanical ventilation (3 [1–7] vs 1 d [2–10 d]; p ≤ 0.001) and increased hospital (17 [10–35] vs 11 d [7–26 d]; p = 0.006) and ICU (7 [4–13] vs 4 d [3–7 d]; p ≤ 0.001) length of stay compared with a negative fluid balance between Day 0–2 . Conclusions: Our results show timing of fluid accumulation not just peak percentage accumulated is associated with patient outcome. Further exploration of the association between time and fluid accumulation is warranted.