Investigators from multiple institutions conducted a series of studies to assess the effects of excess fluid administration on clinical outcomes among children hospitalized for asthma exacerbations. Study participants were children >6 years of age admitted to Boston Children’s Hospital with an asthma exacerbation across a 7-year period beginning in 2010. Only patients who received IV fluids within 24 hours of presentation were enrolled. Fluid overload percent (FO%) was defined as fluid in (both IV and orally) minus fluid output divided by admission weight; the peak FO% was identified as the highest calculated value during the first 72 hours of hospitalization. The main study outcomes included hospital length of stay (LOS), duration of â-agonist therapy, and need for and duration of supplemental oxygen therapy.
For the initial study, the association of these outcomes and FO% was assessed in a retrospective cohort of children. A threshold value for defining fluid overload as a risk factor for duration of supplemental oxygen was determined using receiver operating characteristic (ROC) curve analysis; outcomes in patients with a FO% above or below this threshold value were compared. The validity of this threshold FO% value was evaluated in a second retrospective cohort of children. Patients with a peak FO% above the threshold were matched with children whose calculated peak FO% was below the threshold value, and outcomes were assessed in the 2 groups. Finally, the association between FO% and study outcomes was assessed in a prospective cohort of patients. Both univariate and multivariate analyses were conducted, with the multivariate analyses accounting for potentially confounding variables.
In the initial retrospective cohort, data in 1,175 children with a mean age of 10.5 years were analyzed. Increasing FO% was associated significantly with longer LOS and longer durations of â-agonist therapy and supplemental oxygen (P < .001 for each comparison). With use of the ROC analysis, a threshold value for FO% of 7% was identified. Children with a calculated FO% >7% were significantly more likely to require supplemental oxygen than were those with FO% <7%, even after adjusting for confounding variables (OR, 12.3). The matched retrospective study included 83 children who had calculated FO% >7% (mean, 8.9%) and 83 with an FO% <7% (mean, 2.9%). LOS was significantly longer in the higher FO% group than in those with lower FO% values (mean LOS, 101.8 and 53.6 hours, respectively; P < .001). In addition, the durations of â-agonist therapy and supplemental oxygen were longer in those with a peak FO% >7% (P < .001 for both comparisons). The results were similar among the prospective cohort that included 123 children.
The authors conclude that excess fluid administration is associated with worse clinical outcomes in children hospitalized with asthma exacerbations.