Enteral Resuscitation with WHO Oral Rehydration Salts Ameliorates Burn‐Induced Kidney Injury (AKI) and is Protective of the Glomerular Glycocalyx in a Swine Model

Abstract

Following severe burn injury oral resuscitation fluid may be sufficient to treat patients, especially when i.v. fluid may be delayed such as in mass casualty scenarios. The World Health Organization (WHO) Oral Rehydration Salts (ORS) formulation is designed for treatment of severe dehydration however; its effectiveness at maintaining kidney function and perfusion after burn has not been studied. The objective of this study was to evaluate the effectiveness of ORS and water on post‐burn Acute Kidney Injury (AKI). Anesthetized Yorkshire pigs sustained 40% TBSA full‐thickness contact burns [with brass probes heated to 100°C placed on the skin for 30 seconds]. Animals recovered in metabolic cages and were randomized to one of four treatment groups: no water access (n=7), ad libitum water access (n=6), 15 mL/kg/d of ORS (n=6), or 70 mL/kg/d ORS (n=6) for a 48 hour period. Urine and blood were collected at baseline (BL), 6, 12, 24, 32, and 48‐hour post‐burn for quantification of biochemical markers. Regardless of treatment, all animals experienced AKI as demonstrated by a 0.50±0.10 mg/dL elevation in plasma creatinine by 6 hours following burn. However, animals receiving 70 mL/kg/d ORS or ad libitum water had reduced plasma creatinine by 24 hours, as levels were 1.30±.21 and 1.30±0.13 respectively. Myoglobin was also elevated by 6 hours post‐burn but differences among treatments were not detected. Additionally, preliminary experiments demonstrated elevated free hemin in the urine and plasma following burn in water restricted animals. Animals receiving 70 mL/kg/d ORS also had similar renal wet to dry ratios as the ad libitum group, but both ratios were greater than the water restricted group (p < 0.05), indicating maintained renal perfusion. Moreover, glycosaminoglycan (GAG) concentrations in the urine were elevated post‐burn in all groups suggesting degradation of the glomerular glyocalyx. However, by 48 hours, 70 mL/kg/d animals had reduced urine GAGs when compared to other treatments. Collectively, these data demonstrate that water restriction in burn‐trauma exacerbates burn induced AKI and 70 mL/kg/d of ORS was as sufficient as ad libitum water in alleviating AKI, with preferential protection of the endothelial glycocalyx in the glomerulus. This study highlights the importance of hydration status in response to burn injury, and supports the use of oral resuscitation efforts in burn casualties in prolonged care and mass casualty scenarios.