Effect of initial infusion rates of fluid resuscitation on outcomes in patients with septic shock: a historical cohort study

BACKGROUND: Fluid resuscitation has become the cornerstone of early septic shock management, but the optimal fluid rate is still not well studied. The goal of this investigation is to examine the relationship between fluid resuscitation rate and septic shock resolution. METHOD: We retrospectively studied adult (≥ 18 years) patients with septic shock, defined based on sepsis III definition, from January 1, 2006, through May 31, 2018, in the medical intensive care unit (MICU) of Mayo Clinic Rochester. The fluid resuscitation time was defined as the time required to infuse the initial fluid bolus of 30 ml/kg, based on the recommendations of the 2016 surviving sepsis campaign. The cohort was divided into four groups based on the average fluid rate (group 1 ≥ 0.5, group 2 0.25–0.49, group 3 0.17–0.24, and group 4 < 0.17 ml/kg/min). The primary outcome was the time to shock reversal. Multivariable regression analyses were conducted to account for potential confounders. RESULT: A total of 1052 patients met eligibility criteria and were included in the analysis. The time-to-shock reversal was significantly different among the groups (P < .001). Patients in group 1 who received fluid resuscitation at a faster rate had a shorter time to shock reversal (HR = 0.78; 95% CI 0.66–0.91; P = .01) when compared with group 4 with a median (IQR) time-to-shock reversal of 1.7 (1.5, 2.0) vs. 2.8 (2.6, 3.3) days, respectively. Using 0.25 ml/kg/min as cutoff, the higher fluid infusion rate was associated with a shorter time to shock reversal (HR = 1.22; 95% CI 1.06–1.41; P = .004) and with decreased odds of 28-day mortality (HR = 0.71; 95% CI 0.60–0.85; P < .001). CONCLUSION: In septic shock patients, initial fluid resuscitation rate of 0.25–0.50 ml/kg/min (i.e., completion of the initial 30 ml/kg IV fluid resuscitation within the first 2 h), may be associated with early shock reversal and lower 28-day mortality compared with slower rates of infusion.