Association of hidden fluid administration with development of fluid overload reveals opportunities for targeted fluid minimization

BACKGROUND: Fluid overload is associated with poor outcomes, but mitigating its occurrence poses significant challenges. OBJECTIVE: This study sought to assess the impact of hidden fluid volume on fluid overload. METHODS: This study was a multi-center, retrospective evaluation of adults admitted to a medical or surgical intensive care unit for at least 72 h. Patients were divided into tertiles (low, moderate, and high) based on the hidden fluid volume received. Hidden fluids were defined as intravenous medications, line flushes, blood products, and enteral nutrition. The primary outcome was the incidence of fluid overload at intensive care unit (day 3). Secondary outcomes included mechanical-ventilation free days and association of hidden fluid volume with fluid overload, length of stay, and mortality. RESULTS: A total of 219 (73 per tertile) were included, with hidden fluid volume comprising ⩽2500, 2501–4400, and >4400 mL in the low, moderate, and high tertiles, respectively. Incidence of fluid overload was significantly different across groups (low: 3%, moderate: 14%, high: 25%; p < 0.001). No difference existed in mechanical-ventilation free days or in-hospital mortality across tertiles. In binary logistic regression, hidden fluid volume received at 3 days was independently associated with fluid overload (odds ratio = 1.40, 95% confidence interval = 1.15–1.70). CONCLUSION: The volume of hidden fluid volume administered by intensive care unit day 3 independently predicted development of fluid overload.