Fluid therapy plays a crucial role in the management of sepsis, a life-threatening condition characterized by systemic inflammation. However, there is limited guidance and evidence regarding the optimal rate at which these fluid boluses should be administered. The typical understanding is that a fluid bolus consists of an infusion of 250 to 500 mL for adults, given over 20 to 30 minutes, although there can be significant variability.
Intravenous fluid infusion, although increasing intravascular volume and improving hemodynamics, can pose adverse effects. Rapid administration of large fluid volumes may result in fluid accumulation in the interstitial space, leading to lung and organ edema. Additionally, it has the potential to damage the extracellular matrix, disturb the acid-base balance, and cause harm to the endothelial glycocalyx.
Findings of animal studies and clinical studies indicate that slower infusion led to lower mortality in two studies, decreased blood loss in one study, improved plasma volume expansion and reduced edema in three studies. However, one study reported slower restoration of blood pressure [1].
How fast do you infuse a fluid bolus (500 mL) to your critically ill patients?
20-30 minutes
Over 60 minutes
1-2 hours
In this blog post, we will explore the findings of a systematic review that investigated the impact of rapid infusion rates on stroke volume and cardiac output, as well as the results of a randomized controlled trial comparing slower and faster infusion rates in critically ill patients with sepsis.
Hemodynamic Effects of Fast Fluid Bolus
A systematic review, encompassing 85 studies and 3601 patients, shed light on the association between rapid infusion rates (completed within 30 minutes) and improvements in stroke volume or cardiac output following fluid administration. The review suggests that rapid infusion rates may enhance hemodynamic parameters, most likely by effectively increasing venous return and preload. Interestingly, the volume of fluid used varied among the trials, with less than 500 mL in 12.7% of cases, 500 mL in 79.4%, and more than 500 mL in 7.9% of reports. While these findings indicate a higher probability of hemodynamic improvement with rapid infusion rates, the impact on patient-centered outcomes remains uncertain [2].
Mortality Effect of Slow versus Fast Infusion Rates
A notable randomized controlled trial involving 10,520 critically ill patients requiring IV fluid therapy compared infusion rates of 333 mL/hour (slower rate) versus 999 mL/hour (faster rate). Not surprisingly, the trial found no statistically significant difference in mortality rates between the two groups, with rates of 26.6% in the slower infusion group and 27.0% in the faster infusion group (P = .46) [3]. However, a post hoc analysis revealed that faster infusion rates were associated with a significant survival benefit in a subgroup of patients with sepsis [4]. This suggests that the effects of different infusion rates may vary depending on the patient population and underlying conditions.
Insight
Despite the valuable insights provided by the systematic review and randomized controlled trial, the effects of different infusion rates on outcomes in critically ill patients with sepsis remain unclear. The complex nature of sepsis, individual patient variations, and the potential for confounding factors necessitate further investigation. Rigorous randomized controlled trials, incorporating larger sample sizes and stratified analyses, are needed to elucidate the optimal fluid infusion rates and their impact on mortality, organ dysfunction, and other relevant clinical outcomes in septic patients.
Conclusion:
Rapid fluid infusion rates could potentially enhance stroke volume and cardiac output but their effect on patient-centered outcomes, especially in septic patients, remains unclear. Variability of effects based on patient conditions underscores the need for further rigorous investigations.
References:
Alves JAM, Magalhães MR, Zampieri FG, Veiga VC, Maia IS, Cavalcanti AB. Physiological and clinical effects of different infusion rates of intravenous fluids for volume expansion: a scoping review.  J Crit Care. Published online March 29, 2023. doi:10.1016/j.jcrc.2023.154295 Link
Toscani L, Aya HD, Antonakaki D, et al. What is the impact of the fluid challenge technique on diagnosis of fluid responsiveness? a systematic review and meta-analysis. Crit Care. 2017;21(1):207. doi:10.1186/s13054-017-1796-9 Link
Zampieri FG, Machado FR, Biondi RS, et al; BaSICS Investigators and the BRICNet members. Effect of slower vs faster intravenous fluid bolus rates on mortality in critically ill patients: the BaSICS randomized clinical trial.  JAMA. 2021;326(9):830-838. doi:10.1001/jama.2021.11444 Link
Zampieri FG, Damiani LP, Bagshaw SM, et al; BRICNet. Conditional treatment effect analysis of two infusion rates for fluid challenges in critically ill patients: a secondary analysis of Balanced Solution versus Saline in Intensive Care Study (BaSICS) trial.  Ann Am Thorac Soc. Published online February 3, 2023. doi:10.1513/AnnalsATS.202211-946O Link