Balancing Fluid Resuscitation in Pediatric Sepsis*

Abstract

F luid resuscitation remains a mainstay of sepsis treatment in children and adults. Historically, pediatric guidelines endorsed early, "aggressive" fluid resuscitation for children with sepsis. Compliance with these guidelines, that often-included large amount of fluid resuscitation, led to early recognition of sepsis and significant reductions in mortality in both developed and developing countries (1). More recently, however, there is growing recognition that IV fluids are not innocuous. Both quantitative and qualitative aspects of fluid resuscitation are being questioned, and concerns over issues such as fluid overload or fluid-induced hyperchloremic acidosis are being increasingly debated. These changes were reflected on the most recent pediatric Surviving Sepsis Campaign recommendations, that now support a more individualized approach to the use of fluid boluses and recommend the use of balanced/buffered crystalloids over 0.9% saline for the initial resuscitation of children with septic shock (2).The latter recommendation on balanced fluids was based on "very low quality of evidence" and the Campaign appropriately called for further high-quality pediatric data. In this issue of Pediatric Critical Care Medicine, Fernández-Sarmiento et al (3) make their important contribution to this topic. The authors assessed glycocalyx disruption associated with balanced and unbalanced fluid boluses in children with sepsis. The authors measured perfused boundary region (PBR) on sublingual video microscopy to assess endothelial glycocalyx thickness and blood levels of syndecan-1 as a biomarker for glycocalyx degradation. The study found that glycocalyx thickness decreased significantly 6 hours after fluid bolus in children receiving unbalanced fluids, while it remained mostly unchanged in children receiving a balanced fluid. The glycocalyx thickness reduction was associated with chloride and albumin levels, as well as markers of infection and inflammation. This is a very interesting topic because the glycocalyx regulates many of the key pathophysiological processes associated with sepsis and organ dysfunction. The glycocalyx is a ubiquitous protective layer lining the luminal surface of endothelial cells. It functions as more than just a physical barrier, it regulates essential aspects of microvascular homeostasis, helping to control microvascular permeability, mediate shear-induced vasorelaxation, and modulate cellwall interactions (4, 5). Glycocalyx loss exposes the endothelium and leads to increased fluid shift, edema, loss of vascular responsiveness, and leukocyte/ platelet endothelial interaction with increased inflammation and hypercoagulability. Controlling these processes would likely have a massive effect on the management and outcome of patients with sepsis.Although the glycocalyx was first visualized more than 50 years ago, its direct visualization in vivo remains a challenge. In the study by Fernández-Sarmiento et *See also p. 213.