Approximately 5,000 children die from septic shock each year in the US and thousands more die worldwide. Despite widespread implementation of resuscitation protocols, contemporary studies still report 2-6% mortality for children with septic shock treated in the pediatric emergency department (ED). In the investigators' recent survey of the Pediatric Emergency Care Applied Research Network (PECARN), 45% of physicians had treated a child for septic shock in the ED who subsequently died in the hospital in the past two years.

Fluid resuscitation is the cornerstone of resuscitation for hypovolemia and shock, and intravenous fluids are among the most commonly used therapies worldwide. Yet, there remains uncertainty as to the most appropriate fluid type to restore effective blood volume and optimize organ perfusion. In the absence of a clear role for the early use colloids, administration of crystalloid fluids is generally preferred (except in cases of hemorrhage). For septic shock, in particular, crystalloid fluids have long been the standard resuscitative fluid. Crystalloid fluids can be categorized as non-buffered (most commonly 0.9% normal saline \[NS\]) or buffered/balanced (in the US, this is most commonly lactated Ringer's \[LR\]) solutions. NS and LR are inexpensive, stable at room temperature, and nearly universally available with identical storage volumes and dosing strategies. Notably, both are also of proven clinical benefit in septic shock and have extensive clinical experience for use in fluid resuscitation of critically ill patients. However, while NS is currently used in 80-95% of cases of septic shock, an increasing body of data now suggest that LR resuscitation may have superior efficacy and safety. Buffered crystalloids, including LR, have demonstrated a 1-4% absolute mortality reduction and up to a 50% lower odds of dialysis compared to NS in observational and non-randomized interventional studies in adult sepsis. Nevertheless, because definitive conclusions have not been able to be drawn from existing observational and non-randomized studies, NS overwhelmingly remains the most commonly used fluid based on historical precedent while controversy remains.

To definitively test the comparative effectiveness of NS and LR, a well-powered randomized controlled trial (RCT) is necessary. A large pragmatic randomized trial embedded within everyday clinical practice provides a cost-efficient and generalizable approach to inform clinicians about best comparative effectiveness of common therapies. Unlike explanatory RCTs, pragmatic trials need heterogeneity in patients, non-study therapies, and settings. To accomplish this, these trials must be large enough to detect small effects and simple enough to incorporate into routine clinical practice. The characteristics of LR and NS provide the ideal scenario for a large pragmatic trial.18 An ED-based trial is necessary to enroll patients at initiation of resuscitation. While any benefit is expected to be small, even a 1-2% absolute reduction in mortality that is in line with prior adult studies would be a clinically important difference by saving the lives of 50-100 children in the US (and many more worldwide) each year. This overall public health impact is commensurate with changing from NS to LR because such a practice change is a simple, cost-neutral shift from largely using NS to largely using LR.

However, before embarking on a large, pragmatic randomized trial that will determine the comparative effectiveness and safety of NS and LR, several concerns regarding feasibility of such a trial need to be addressed including a) ensuring adequate compliance with study fluid administration within each randomized arm using the proposed pragmatic study design, b) determining that a sufficient proportion of patients can be enrolled using the proposed pragmatic study design that will be embedded within routine clinical practice rather than use of a dedicated study team, and c) demonstrating that the study can feasibly be performed using EFIC when enrolling critically ill infants, children, and adolescents into this clinical trial. Demonstrating these feasibility criteria at a single site will strongly support success in a larger, multicenter study that will enroll several thousand patients across the 18 sites comprising Pediatric Emergency Care Applied Research Network (PECARN) to test morbidity and mortality outcomes.