1748: ESTIMATED VERSUS MEASURED ENERGY EXPENDITURE IN VENTILATED SURGICAL-TRAUMA CRITICALLY ILL PATIENTS

Abstract

Learning Objectives: Refeeding syndrome describes metabolic changes including fluid shifts and fluctuations in glucose, protein, and electrolytes when initiating nutrition in critically ill patients; however, a new definition has been established as refeeding hypophosphatemia. This term specifically describes phosphorus depletion upon nutrition initiation. The objective of this study is to classify electrolyte deficiencies in trauma patients as either refeeding syndrome or refeeding hypophosphatemia and to define risk factors for each. Methods: This retrospective chart review included adult trauma patients admitted from 10/1/16 to 8/31/17 with at least a 7 day length of stay after injury. The primary outcome was to assess electrolyte deficiencies including hypophosphatemia (< 2.5 mg/dL), hypokalemia (< 3.5 mg/dL), and hypomagnesemia (< 1.6 mg/dL), and to classify these deficiencies. Refeeding syndrome was defined as deficiencies in potassium, magnesium, and phosphorus at any point. Refeeding hypophosphatemia was defined as hypophosphatemia at any point during the 7 day period. Baseline demographics were compared between groups to assess risk factors for each type of disorder. Results: A total of 175 patients met inclusion criteria. Groups were well-matched at baseline. On Day 0, patients had average potassium, magnesium, and phosphorus levels within normal ranges. Median (IQR) nadir magnesium levels were within normal range. Nadir potassium [3.5 mEq/L (3.2-3.6); p < 0.01] and phosphorus [1.7 mg/dL (1.0-2.2); p < 0.01] were below normal ranges. By Day 7, all levels had returned to normal. Of the patients able to be classified, significantly more were likely to be classified as refeeding hypophosphatemia [85 (51.5%)] versus either refeeding syndrome [33 (20%)] or neither deficiency [47 (28.5%)] (p < 0.01). There was a significant difference in median injury severity scores (ISS) between groups, with patients in the refeeding hypophosphatemia group classified as severe [19 (11-27)] versus moderate in the refeeding syndrome [14 (9-23)] or neither deficiency groups [14 (9-19)]. Conclusions: Results indicate patients with severe ISS are more likely to have refeeding hypophosphatemia than refeeding syndrome or neither, likely due to their hypermetabolic state. Our study defines electrolyte deficiencies in trauma patients for use in a replacement protocol. To our knowledge, this is the first study to evaluate risk factors for refeeding syndrome versus refeeding hypophosphatemia in critically ill patients.