Renin signals renal hypoperfusion during Parkland fluid resuscitation of severe burns - a prospective longitudinal cohort study.

INTRODUCTION Previous investigations have shown that fluid resuscitation of burns using the Parkland formula results in controlled hypovolaemia and that kidney injury is a common complication. Enhancing monitoring of tissue perfusion might reduce complications. Plasma renin has recently been suggested to be a promising marker for tissue hypoperfusion in intensive care patients. The aim of this study was to explore plasma renin levels during the first 48 hours after major burns in patients resuscitated using the Parkland formula. MATERIALS AND METHODS Patients 18 years or older of age with 10% or more total body surface area (TBSA) burned, admitted to Linkoping Burn Intensive Care Unit, and resuscitated using the Parkland formula were included. Samples for plasma renin were drawn at admission and eight-hourly thereafter for 48 hours. RESULTS Fifteen patients were included. Median TBSA burned was 36% and age 53 years. The fluid volumes provided were in accordance with the Parkland formula. Mean arterial pressure, urinary output, and lactate remained within reference ranges during the first 48 hours. At eight hours after burn median plasma renin was elevated to more than 25 times the upper reference value, decreasing to about four times the upper reference at 48 hours. Renin concentration was associated with lactate levels and TBSA burned. CONCLUSION During Parkland fluid resuscitation of severe burns, plasma renin levels were extremely elevated. The fact that the traditionally used endpoints for Parkland fluid resuscitation remained within the reference range raises concerns about whether the increased renin concentrations may signal a relative renal hypoperfusion.