Assessment of the components of fluid balance in patients with septic shock: a prospective observational study

The optimal amount for initial fluid resuscitation is still controversial in sepsis and the contribution of non-resuscitation fluids in fluid balance is unclear. We aimed to investigate the main components of fluid intake and fluid balance in both survivors and non-survivor patients with septic shock within the first 72 hours.

In this prospective observational study in two intensive care units, we recorded all fluids administered intravenously, orally, or enterally, and losses during specific time intervals from vasopressor initiation: T1 (up to 24 hours), T2 (24 to 48 hours) and T3 (48 to 72 hours). Logistic regression and a mathematical model assessed the association with mortality and the influence of severity of illness.

We included 139 patients. The main components of fluid intake varied across different time intervals, with resuscitation and non-resuscitation fluids such as antimicrobials and maintenance fluids being significant contributors in T1 and nutritional therapy in T2/T3. A positive fluid balance both in T1 and T2 was associated with mortality (p = 0.049; p = 0.003), while nutritional support in T2 was associated with lower mortality (p = 0.040). The association with mortality was not explained by severity of illness scores.

Non-resuscitation fluids are major contributors to a positive fluid balance within the first 48 hours of resuscitation. A positive fluid balance in the first 24 and 48 hours seems to independently increase the risk of death, while higher amount of nutrition seems protective. This data might inform fluid stewardship strategies aiming to improve outcomes and minimize complications in sepsis.