Indications for fluid resuscitation in patients with septic shock: Post-hoc analyses of the CLASSIC trial

Background Fluid resuscitation is recommended in septic shock, but the specific indications for fluids have not been established. Our aim was to investigate the indications currently used for fluid resuscitation and the effect of fluid on these indications in patients with septic shock admitted to the intensive care unit (ICU). Methods This was a post-hoc analysis of the CLASSIC trial, where patients with septic shock were randomized to fluid restriction or standard care. We recorded indications for and effect of each fluid bolus during the first 24 hours. Results In total, 256 fluid boluses were administered on 515 indications to the 76 patients in the standard care group. The most frequent indications were low blood pressure/increase in noradrenalin dose (199 boluses, 78%), high lactate (94, 37%), and low urinary output (68, 27%). While the analyses of all 418 fluid boluses given in all 151 patients failed to show any effect of fluid on these variables, the data did suggest that time from randomization altered the effect; fluid may have increased urinary output when given early and increased noradrenalin dose when given later. For 56% of the fluid boluses given on the most frequent indications, a second fluid bolus was given on the same indication. Conclusions In ICU patients with septic shock, low blood pressure, high lactate, and low urinary output were the most frequent indications for fluid. The effects of fluids when given on these indications were less clear, but may dependent on the time course of sepsis resuscitation.